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Publications de l'équipe Procédés et mécanique aux petites échelles
2023
Revaz Chachanidze, Kaili Xie, Jinming Lyu, Marc Jaeger, Marc Leonetti. Breakups of Chitosan microcapsules in extensional flow. Journal of Colloid and Interface Science, 2023, 629, pp.445-454. ⟨10.1016/j.jcis.2022.08.169⟩. ⟨hal-03787637⟩ Plus de détails...
The controlled rupture of a core-shell capsule and the timely release of encapsulated materials are essential steps of the efficient design of such carriers. The mechanical and physico-chemical properties of their shells (or membranes) mainly govern the evolution of such systems under stress and notably the link between the dynamics of rupture and the mechanical properties. This issue is addressed considering weakly cohesive shells made by the interfacial complexation of Chitosan and PFacid in a planar extensional flow. Three regimes are observed, thanks to the two observational planes. Whatever the time of reaction in membrane assembly, there is no rupture in deformation as long as the hydrodynamic stress is below a critical value. At low times of complexation (weak shear elastic modulus), the rupture is reminiscent of the breakup of droplets: a dumbell or a waist. Fluorescent labelling of the membrane shows that this process is governed by continuous thinning of the membrane up to the destabilization. It is likely that the membrane shows a transition from a solid to liquid state. At longer times of complexation, the rupture has a feature of solid-like breakup (breakage) with a discontinuity of the membrane. The maximal internal constraint determined numerically marks the initial location of breakup as shown. The pattern becomes more complex as the elongation rate increases with several points of rupture. A phase diagram in the space parameters of the shear elastic modulus and the hydrodynamic stress is established.
Revaz Chachanidze, Kaili Xie, Jinming Lyu, Marc Jaeger, Marc Leonetti. Breakups of Chitosan microcapsules in extensional flow. Journal of Colloid and Interface Science, 2023, 629, pp.445-454. ⟨10.1016/j.jcis.2022.08.169⟩. ⟨hal-03787637⟩
Antoine Galko, Simon Gsell, Umberto d'Ortona, Laurent Morin, Julien Favier. Pulsated Herschel-Bulkley flows in two-dimensional channels: A model for mucus clearance devices. Physical Review Fluids, 2022, 7 (5), pp.053301. ⟨10.1103/PhysRevFluids.7.053301⟩. ⟨hal-03863329⟩ Plus de détails...
Umberto d'Ortona, Nathalie Thomas, Richard M Lueptow. Mechanisms for recirculation cells in granular flows in rotating cylindrical rough tumblers. Physical Review E, 2022. ⟨hal-03431772v2⟩ Plus de détails...
Friction at the endwalls of partially-filled horizontal rotating tumblers induces curvature and axial drift of particle trajectories in the surface flowing layer. Here we describe the results of a detailed discrete element method study of the dry granular flow of monodisperse particles in threedimensional cylindrical tumblers with endwalls and cylindrical wall that can be either smooth or rough. Endwall roughness induces more curved particle trajectories, while a smooth cylindrical wall enhances drift near the endwall. This drift induces recirculation cells near the endwall. The use of mixed roughness (cylindrical wall and endwalls having different roughness) shows the influence of each wall on the drift and curvature of particle trajectories as well as the modification of the free surface topography. The effects act in opposite directions and have variable magnitude along the length of the tumbler such that their sum determines both direction of net drift and the recirculation cells. Near the endwalls, the dominant effect is always the endwall effect, and the axial drift for surface particles is toward the endwalls. For long enough tumblers, a counter-rotating cell occurs adjacent to each of the endwall cells having a surface drift toward the center because the cylindrical wall effect is dominant there. These cells are not dynamically coupled with the two endwall cells. The competition between the drifts induced by the endwalls and the cylindrical wall determines the width and drift amplitude for both types of cells.
Umberto d'Ortona, Nathalie Thomas, Richard M Lueptow. Mechanisms for recirculation cells in granular flows in rotating cylindrical rough tumblers. Physical Review E, 2022. ⟨hal-03431772v2⟩
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03597451⟩ Plus de détails...
The well-known Villermaux-Dushman system is nowadays widely used for examining the micromixing efficiency either in batch or continuous intensified reactors. However, a bibliographic review shows that kinetic data are too scattered for a reliable determination of the micromixing times. The Dushman reaction kinetics is then reexamined with the use of sulfuric and perchloric acids. The results confirm the fifth-order rate law. More precisely, the I-, H+, and IO3- dependence orders on the rate law are, respectively, 2, 2, and 1, under any condition. To be more consistent with the reactant concentrations used in the Villermaux-Dushman test, we extend their studied range, namely, 1.6 x 10(-3) M <= [I-](0) <= 1.6 x 10(-2) M, 1.2 x 10(-4) M <= [H+](0) <= 1.57 x 10(-2) M, and 4 x 10(-5) M <= [IO3-] <= 2.1 X 10(-4) M. The ionic strength varies up to 2 M. The experimental results show that the rate constant is still ionic-strength-dependent. The results obtained with sulfuric and perchloric acids are found to be consistent and in relatively good agreement at small ionic strengths (mu < 0.1 M) only. At a higher ionic strength, the use of sulfuric acid requires sustained attention to the constant of the second dissociation equilibrium. The nonideal solution behavior raising at a high ionic strength makes its estimation deeply sensitive.
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03597451⟩
Journal: Industrial and engineering chemistry research
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03514628⟩ Plus de détails...
The well-known Villermaux-Dushman system is nowadays widely used for examining the micromixing efficiency either in batch or continuous intensified reactors. However, a bibliographic review shows that kinetic data are too scattered for a reliable determination of the micromixing times. The Dushman reaction kinetics is then reexamined with the use of sulfuric and perchloric acids. The results confirm the fifth-order rate law. More precisely, the I-, H+, and IO3- dependence orders on the rate law are, respectively, 2, 2, and 1, under any condition. To be more consistent with the reactant concentrations used in the Villermaux-Dushman test, we extend their studied range, namely, 1.6 x 10(-3) M <= [I-](0) <= 1.6 x 10(-2) M, 1.2 x 10(-4) M <= [H+](0) <= 1.57 x 10(-2) M, and 4 x 10(-5) M <= [IO3-] <= 2.1 X 10(-4) M. The ionic strength varies up to 2 M. The experimental results show that the rate constant is still ionic-strength-dependent. The results obtained with sulfuric and perchloric acids are found to be consistent and in relatively good agreement at small ionic strengths (mu < 0.1 M) only. At a higher ionic strength, the use of sulfuric acid requires sustained attention to the constant of the second dissociation equilibrium. The nonideal solution behavior raising at a high ionic strength makes its estimation deeply sensitive.
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03514628⟩
Journal: Industrial and engineering chemistry research
Oleksandr Dimitrov, Pierrette Guichardon, Isabelle Raspo, Evelyne Neau. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part II: Modeling Based on the NRTL-PR Model. Industrial and engineering chemistry research, 2021, 60 (30), pp.11513-11524. ⟨10.1021/acs.iecr.1c01545⟩. ⟨hal-03379757⟩ Plus de détails...
Further to the Part I of the present paper, the second Part is concentrated around the VLE modeling of binary mixtures involving the three glycol ethers previously studied experimentally. The authors propose to use the NRTL-PR model for the representation of these non-ideal mixtures. The main diﬃculties of modelling related to very low vapor pressures and the way of dealing with them are highlighted. The unknown critical parameters for DPM, DPnB and PnB were determined using robust group contribution methods. However, the experimental values of these parameters have never been published before. The main goal of the authors was to obtain the most satisfactory representation of the experimental data provided in the Part I. Some issues that mostly occurred in mixtures involving the PnB as well as in mixtures having very low vapor pressures, were encountered. Nevertheless, we have obtained in general a satisfactory representation of measured points regardless of those issues.
Oleksandr Dimitrov, Pierrette Guichardon, Isabelle Raspo, Evelyne Neau. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part II: Modeling Based on the NRTL-PR Model. Industrial and engineering chemistry research, 2021, 60 (30), pp.11513-11524. ⟨10.1021/acs.iecr.1c01545⟩. ⟨hal-03379757⟩
Journal: Industrial and engineering chemistry research
Hadrien Jaubert, Philippe Borel, Pierrette Guichardon, Jean-François Portha, Jean-Noël Jaubert, et al.. Assessment of organic Rankine cycle configurations for solar polygeneration orientated to electricity production and desalination. Applied Thermal Engineering, 2021, 195, pp.116983. ⟨10.1016/j.applthermaleng.2021.116983⟩. ⟨hal-03597561⟩ Plus de détails...
This work addresses the polygeneration concept integrating concentrating solar power (CSP) with an organic Rankine cycle (ORC) to produce electricity and drinking water by hybrid desalination process combining reverse osmosis (RO) and low-temperature multi-effect distillation (LTMED). Experiments carried out on a bench scale RO pilot led to determine optimal operating parameters as well as options to mitigate the main limiting factors of this technology by hybridizing with LTMED. These data helped to simulate a large scale solar polygeneration plant integrating parabolic trough collectors as CSP technology and a hybrid RO-LTMED system as desalination technology. Various ORC design proposals were simulated and the optimal configuration was pointed out on the basis of thermodynamic criteria (energy efficiency and exergy destruction) and an economic analysis by using two working fluids: an alkane commonly admitted as good candidate and an ester proposed here as green alternative. Results obtained in this work contribute positively to extending the solar polygeneration for desalination and production of energy leading to future sustainable plants.
Hadrien Jaubert, Philippe Borel, Pierrette Guichardon, Jean-François Portha, Jean-Noël Jaubert, et al.. Assessment of organic Rankine cycle configurations for solar polygeneration orientated to electricity production and desalination. Applied Thermal Engineering, 2021, 195, pp.116983. ⟨10.1016/j.applthermaleng.2021.116983⟩. ⟨hal-03597561⟩
Sudip Das, Marc Jaeger, Marc Leonetti, Rochish M. Thaokar, Paul G. Chen. Effect of pulse width on the dynamics of a deflated vesicle in unipolar and bipolar pulsed electric fields. Physics of Fluids, 2021, 33 (8), pp.081905. ⟨10.1063/5.0057168⟩. ⟨hal-03317441⟩ Plus de détails...
Giant unilamellar vesicles subjected to pulsed direct-current (pulsed-DC) fields are promising biomimetic systems to investigate the electroporation of cells. In strong electric fields, vesicles undergo significant deformation, which strongly alters the transmembrane potential, consequently the electroporation. Previous theoretical studies investigated the electrodeformation of vesicles in DC fields (which are not pulsed). In this work, we computationally investigate the deformation of a deflated vesicle under unipolar, bipolar, and two-step unipolar pulses and show sensitive dependence of intermediate shapes on type of pulse and the pulse width. Starting with the stress-free initial shape of a deflated vesicle, which is similar to a prolate spheroid, the analysis is presented for the cases with higher and lower conductivities of the inner fluid medium relative to the outer fluid medium. For the ratio of inner to outer fluid conductivity, σ r = 10, the shape always remains prolate, including when the field is turned off. For σ r = 0.1, several complex dynamics are observed, such as the prolate-to-oblate (PO), prolate-to-oblate-to-prolate (POP) shape transitions in time depending upon the strength of the field and the pulse properties. In this case, on turning off the field, a metastable oblate equilibrium shape is seen, that seems to be a characteristics of a deflated vesicle leading to POPO transitions. When a two-step unipolar pulse (a combination of a strong and a weak subpulse) is applied, a vesicle can reach an oblate or a prolate final shape depending upon the relative durations of the two subpulses. This study suggests that the transmembrane potential can be regulated using a bipolar pulsed-DC field. It also shows that the shapes admitted in the dynamics of a vesicle depends upon whether the pulse is unipolar or bipolar. Parameters are suggested wherein, the simulation results can be demonstrated in experiments.
Sudip Das, Marc Jaeger, Marc Leonetti, Rochish M. Thaokar, Paul G. Chen. Effect of pulse width on the dynamics of a deflated vesicle in unipolar and bipolar pulsed electric fields. Physics of Fluids, 2021, 33 (8), pp.081905. ⟨10.1063/5.0057168⟩. ⟨hal-03317441⟩
Oleksandr Dimitrov, Pierrette Guichardon, Ilham Mokbel, Fatiha Dergal, Jacques Jose. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part I: Experimental Study. Industrial and engineering chemistry research, 2021, 60 (26), pp.9602-9612. ⟨10.1021/acs.iecr.1c01543⟩. ⟨hal-03597175⟩ Plus de détails...
An experimental and theoretical study was undertaken for three ether glycols (mixtures of isomers). The present paper, being the first part of a complex study, reports the experimental part of the study using a static apparatus, namely, the vapor-liquid equilibria of dipropylene glycol methyl ether (DPM), dipropylene glycol n-butyl ether (DPnB), and propylene glycol n-butyl ether (PnB), and the vapor-liquid equilibria of their pseudo-binary mixtures composed of (PnB + DPM), (DPM + DPnB), (PnB + DPnB), and the aqueous solutions of each ether. The explored temperature range is between 283.15 and 363.15 K. The experimental points were fitted using the Antoine equation. No literature data was found for comparison. The aim of this paper is not only to provide the obtained experimental data but also to highlight the eventual challenges when working with very low vapor pressure compounds and mixtures. The second part is related to a theoretical study with the development of a thermodynamic model for the representation of the experimental data.
Oleksandr Dimitrov, Pierrette Guichardon, Ilham Mokbel, Fatiha Dergal, Jacques Jose. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part I: Experimental Study. Industrial and engineering chemistry research, 2021, 60 (26), pp.9602-9612. ⟨10.1021/acs.iecr.1c01543⟩. ⟨hal-03597175⟩
Journal: Industrial and engineering chemistry research
Oleksandr Dimitrov, Pierrette Guichardon, Ilham Mokbel, Fatiha Dergal, Jacques Jose. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part I: Experimental Study. Industrial and engineering chemistry research, 2021, 60 (26), pp.9602-9612. ⟨10.1021/acs.iecr.1c01543⟩. ⟨hal-03515186⟩ Plus de détails...
An experimental and theoretical study was undertaken for three ether glycols (mixtures of isomers). The present paper, being the first part of a complex study, reports the experimental part of the study using a static apparatus, namely, the vapor-liquid equilibria of dipropylene glycol methyl ether (DPM), dipropylene glycol n-butyl ether (DPnB), and propylene glycol n-butyl ether (PnB), and the vapor-liquid equilibria of their pseudo-binary mixtures composed of (PnB + DPM), (DPM + DPnB), (PnB + DPnB), and the aqueous solutions of each ether. The explored temperature range is between 283.15 and 363.15 K. The experimental points were fitted using the Antoine equation. No literature data was found for comparison. The aim of this paper is not only to provide the obtained experimental data but also to highlight the eventual challenges when working with very low vapor pressure compounds and mixtures. The second part is related to a theoretical study with the development of a thermodynamic model for the representation of the experimental data.
Oleksandr Dimitrov, Pierrette Guichardon, Ilham Mokbel, Fatiha Dergal, Jacques Jose. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part I: Experimental Study. Industrial and engineering chemistry research, 2021, 60 (26), pp.9602-9612. ⟨10.1021/acs.iecr.1c01543⟩. ⟨hal-03515186⟩
Journal: Industrial and engineering chemistry research
Simon Gsell, Umberto d'Ortona, Julien Favier. Lattice-Boltzmann simulation of creeping generalized Newtonian flows: theory and guidelines. Journal of Computational Physics, 2021, 429, pp.109943. ⟨10.1016/j.jcp.2020.109943⟩. ⟨hal-03166492⟩ Plus de détails...
The accuracy of the lattice-Boltzmann (LB) method is related to the relaxation time controlling the flow viscosity. In particular, it is often recommended to avoid large fluid viscosities in order to satisfy the low-Knudsen-number assumption that is essential to recover hydrodynamic behavior at the macroscopic scale, which may in principle limit the possibility of simulating creeping flows and non-Newtonian flows involving important viscosity variations. Here it is shown, based on the continuous Boltzmann equations, that a two-relaxation-time (TRT) model can however recover the steady Navier-Stokes equations without any restriction on the fluid viscosity, provided that the Knudsen number is redefined as a function of both relaxation times. This effective Knudsen number is closely related to the previously-described parameter controlling numerical errors of the TRT model, providing a consistent theory at both the discrete and continuous levels. To simulate incompressible flows, the viscous incompressibility condition M a 2 /Re 1 also needs to be satisfied, where M a and Re are the Mach and Reynolds numbers. This concept is extended by defining a local incompressibility factor, allowing one to locally control the accuracy of the simulation for flows involving varying viscosities. These theoretical arguments are illustrated based on numerical simulations of the two-dimensional flow past a square cylinder. In the case of a Newtonian flow, the viscosity independence is confirmed for relaxation times up to 10 4 , and the ratio M a 2 /Re = 0.1 is small enough to ensure reliable incompressible simulations. The Herschel-Bulkley model is employed to introduce shear-dependent viscosities in the flow. The proposed numerical strategy allows to achieve major viscosity variations, avoiding the implementation of artificial viscosity cutoff in high-viscosity regions. Highly non-linear flows are simulated over ranges of the Bingham number Bn ∈ [1, 1000] and flow index n ∈ [0.2, 1.8], and successfully compared to prior numerical works based on Navier-Stokes solvers. This work provides a general framework to simulate complex creeping flows, as encountered in many biological and industrial systems, using the lattice-Boltzmann method.
Simon Gsell, Umberto d'Ortona, Julien Favier. Lattice-Boltzmann simulation of creeping generalized Newtonian flows: theory and guidelines. Journal of Computational Physics, 2021, 429, pp.109943. ⟨10.1016/j.jcp.2020.109943⟩. ⟨hal-03166492⟩
J Lyu, K Xie, R Chachanidze, A Kahli, Gwenn Boedec, et al.. Dynamics of pearling instability in polymersomes: the role of shear membrane viscosity and spontaneous curvature. Physics of Fluids, In press, 33 (12), pp.122016. ⟨10.1063/5.0075266⟩. ⟨hal-03467425⟩ Plus de détails...
The stability of copolymer tethers is investigated theoretically. Self-assembly of diblock or triblock copolymers can lead to tubular polymersomes which are known experimentally to undergo shape instability under thermal, chemical and tension stresses. It leads to a periodic modulation of the radius which evolves to assembly-line pearls connected by tiny tethers. We study the contributions of shear surface viscosity and spontaneous curvature and their interplay to understand the pearling instability. The performed linear analysis of stability of this cylinder-to-pearls transition shows that such systems are unstable if the membrane tension is larger than a finite critical value contrary to the Rayleigh-Plateau instability, an already known result or if the spontaneous curvature is in a specific range which depends on membrane tension. For the case of spontaneous curvature-induced shape instability, two dynamical modes are identified. The first one is analog to the tension- induced instability with a marginal mode. Its wavenumber associated with the most un- stable mode decreases continuously to zero as membrane viscosity increases. The second one has a finite range of unstable wavenumbers. The wavenumber of the most unstable mode tends redto be constant as membrane viscosity increases. In this mode, its growth rate becomes independent of the bulk viscosity in the limit of high membrane viscosity and behaves as a pure viscous surface.
J Lyu, K Xie, R Chachanidze, A Kahli, Gwenn Boedec, et al.. Dynamics of pearling instability in polymersomes: the role of shear membrane viscosity and spontaneous curvature. Physics of Fluids, In press, 33 (12), pp.122016. ⟨10.1063/5.0075266⟩. ⟨hal-03467425⟩
J Lyu, K Xie, R Chachanidze, A Kahli, Gwenn Boedec, et al.. Dynamics of pearling instability in polymersomes: the role of shear membrane viscosity and spontaneous curvature. Physics of Fluids, American Institute of Physics, 2021, 33 (12), pp.122016. ⟨10.1063/5.0075266⟩. ⟨hal-03597656⟩ Plus de détails...
The stability of copolymer tethers is investigated theoretically. Self-assembly of diblock or triblock copolymers can lead to tubular polymersomes which are known experimentally to undergo shape instability under thermal, chemical and tension stresses. It leads to a periodic modulation of the radius which evolves to assembly-line pearls connected by tiny tethers. We study the contributions of shear surface viscosity and spontaneous curvature and their interplay to understand the pearling instability. The performed linear analysis of stability of this cylinder-to-pearls transition shows that such systems are unstable if the membrane tension is larger than a finite critical value contrary to the Rayleigh-Plateau instability, an already known result or if the spontaneous curvature is in a specific range which depends on membrane tension. For the case of spontaneous curvature-induced shape instability, two dynamical modes are identified. The first one is analog to the tension- induced instability with a marginal mode. Its wavenumber associated with the most un- stable mode decreases continuously to zero as membrane viscosity increases. The second one has a finite range of unstable wavenumbers. The wavenumber of the most unstable mode tends redto be constant as membrane viscosity increases. In this mode, its growth rate becomes independent of the bulk viscosity in the limit of high membrane viscosity and behaves as a pure viscous surface.
J Lyu, K Xie, R Chachanidze, A Kahli, Gwenn Boedec, et al.. Dynamics of pearling instability in polymersomes: the role of shear membrane viscosity and spontaneous curvature. Physics of Fluids, American Institute of Physics, 2021, 33 (12), pp.122016. ⟨10.1063/5.0075266⟩. ⟨hal-03597656⟩
Jinming Lyu, Paul G. Chen, G. Boedec, M. Leonetti, Marc Jaeger. An isogeometric boundary element method for soft particles flowing in microfluidic channels. Computers and Fluids, 2021, 214, pp.104786. ⟨10.1016/j.compfluid.2020.104786⟩. ⟨hal-02476945v2⟩ Plus de détails...
Understanding the flow of deformable particles such as liquid drops, synthetic capsules and vesicles, and biological cells confined in a small channel is essential to a wide range of potential chemical and biomedical engineering applications. Computer simulations of this kind of fluid-structure (mem-brane) interaction in low-Reynolds-number flows raise significant challenges faced by an intricate interplay between flow stresses, complex particles' in-terfacial mechanical properties, and fluidic confinement. Here, we present an isogeometric computational framework by combining the finite-element method (FEM) and boundary-element method (BEM) for an accurate prediction of the deformation and motion of a single soft particle transported in microfluidic channels. The proposed numerical framework is constructed consistently with the isogeometric analysis paradigm; Loop's subdivision elements are used not only for the representation of geometry but also for the membrane mechanics solver (FEM) and the interfacial fluid dynamics solver (BEM). We validate our approach by comparison of the simulation results with highly accurate benchmark solutions to two well-known examples available in the literature, namely a liquid drop with constant surface tension in a circular tube and a capsule with a very thin hyperelastic membrane in a square channel. We show that the numerical method exhibits second-order convergence in both time and space. To further demonstrate the accuracy and long-time numerically stable simulations of the algorithm, we perform hydrodynamic computations of a lipid vesicle with bending stiffness and a red blood cell with a composite membrane in capillaries. The present work offers some possibilities to study the deformation behavior of confining soft particles, especially the particles' shape transition and dynamics and their rheological signature in channel flows.
Jinming Lyu, Paul G. Chen, G. Boedec, M. Leonetti, Marc Jaeger. An isogeometric boundary element method for soft particles flowing in microfluidic channels. Computers and Fluids, 2021, 214, pp.104786. ⟨10.1016/j.compfluid.2020.104786⟩. ⟨hal-02476945v2⟩
Cláudio P Fonte, David Fletcher, Pierrette Guichardon, Joelle Aubin. Simulation of micromixing in a T-mixer under laminar flow conditions. Chemical Engineering Science, 2020, 222, pp.115706. ⟨10.1016/j.ces.2020.115706⟩. ⟨hal-02892241⟩ Plus de détails...
The CFD simulation of fast reactions in laminar flows can be computationally challenging due to the lack of appropriate sub-grid micromixing models in this flow regime. In this work, simulations of micromixing via the implementation of the competitive-parallel Villermaux/Dushman reactions in a T-micromixer with square bends for Reynolds numbers in the range 60–300 are performed using both a conventional CFD approach and a novel lamellae-based model. In the first, both the hydrodynamics and the concentration fields of the reaction species are determined directly using a finite volume approach. In the second, the hydrodynamic field from the CFD calculations is coupled with a Lagrangian model that is used to perform the chemical reactions indirectly. Both sets of results are compared with previously published experimental data and show very good agreement. The lamellar model has the advantage of being much less computationally intensive than the conventional CFD approach, which requires extremely fine computational grids to resolve sharp concentration gradients. It is a promising solution to model fast chemical reactions in reactors with complex geometries in the laminar regime and for industrial applications.
Cláudio P Fonte, David Fletcher, Pierrette Guichardon, Joelle Aubin. Simulation of micromixing in a T-mixer under laminar flow conditions. Chemical Engineering Science, 2020, 222, pp.115706. ⟨10.1016/j.ces.2020.115706⟩. ⟨hal-02892241⟩
Jiupeng Du, Nelson Ibaseta, Pierrette Guichardon. Generation of an O/W emulsion in a flow-focusing microchip: importance of wetting conditions and of dynamic interfacial tension. Chemical Engineering Research and Design, 2020, ⟨10.1016/j.cherd.2020.04.012⟩. ⟨hal-02799613⟩ Plus de détails...
6 To date, there is no information on the microfluidic emulsification of dibutyl adipate and 7 n-butyl acetate in water. Since these solvents are very suitable for microencapsulation by 8 interfacial polymerization, it is highly necessary to study the emulsification behavior of these 9 solvents in microchannel. This work shows that the microfluidic emulsification of these sol-10 vents in water may fail to obtain stabilized flow regimes. This is due to droplet coalescence 11 and wall wetting, even if a hydrophilic microchip is used. Hydrodynamic results show that 12 squeezing and dripping regimes are especially affected because of the wall wetting by the 13 dispersed phase. This difficulty can be circumvented by adding a surfactant (here Tween 14 80) into the aqueous phase. However, high surfactant concentrations (ten times the crit-15 ical micelle concentration) should be used for the water-dibutyl adipate system. Indeed, 16 comparison of flow maps for several surfactant concentrations seems to indicate that the 17 dynamic interfacial tension is higher than the one expected (equilibrium), for surfactant 18 concentrations lower than one hundred times the critical micelle concentration. The esti-19 mated diffusion time of Tween 80 is compared to the droplet formation time at different 20 conditions. The choice of more appropriate dimensionless numbers to represent flow maps 21 is also discussed. 22
Jiupeng Du, Nelson Ibaseta, Pierrette Guichardon. Generation of an O/W emulsion in a flow-focusing microchip: importance of wetting conditions and of dynamic interfacial tension. Chemical Engineering Research and Design, 2020, ⟨10.1016/j.cherd.2020.04.012⟩. ⟨hal-02799613⟩
Kelly Ohanessian, Mathias Monnot, Philippe Moulin, Jean-Henry Ferrasse, Cristian Barca, et al.. Dead-end and crossflow ultrafiltration process modelling: Application on chemical mechanical polishing wastewaters. Chemical Engineering Research and Design, 2020, 158, pp.164-176. ⟨10.1016/j.cherd.2020.04.007⟩. ⟨hal-02892457⟩ Plus de détails...
Dynamic simulation of ultrafiltration process is applied to the treatment of chemical mechanical polishing wastewater from microelectronic industry. The ultrafiltration of nanoparticles (NPs) contained in chemical mechanical polishing wastewater is modelled by using different mathematical equations, which are derived from the literature and optimized to the effluent and filtration modes (dead-end or crossflow). A series of ultrafiltration experiments at laboratory scale are carried out by using chemical mechanical polishing wastewater to optimize and validate the models. Complete dead-end and crossflow ultrafiltration models are developed to simulate the treatment performances of chemical mechanical polishing wastewater under dynamic full-scale and different operating conditions, thus including filtration and washing steps. Simulations show that the dead-end mode is not suitable for chemical mechanical polishing wastewater concentration higher than 100 mgNPs L-1 due to the too fast fouling time and to the high frequency of washing step. The high concentration of chemical mechanical polishing P wastewater (2600 mgNPs L-1) forces industries to use crossflow ultrafiltration to have a profitable process by controlling parameters such as the filtration/backwashing number of cycles, the needed filtering surface and the filtration flux.
Kelly Ohanessian, Mathias Monnot, Philippe Moulin, Jean-Henry Ferrasse, Cristian Barca, et al.. Dead-end and crossflow ultrafiltration process modelling: Application on chemical mechanical polishing wastewaters. Chemical Engineering Research and Design, 2020, 158, pp.164-176. ⟨10.1016/j.cherd.2020.04.007⟩. ⟨hal-02892457⟩
Paul G. Chen, J M Lyu, M Jaeger, M. Leonetti. Shape transition and hydrodynamics of vesicles in tube flow. Physical Review Fluids, 2020, 5 (4), pp.043602. ⟨10.1103/PhysRevFluids.5.043602⟩. ⟨hal-02415320v2⟩ Plus de détails...
The steady motion and deformation of a lipid-bilayer vesicle translating through a circular tube in low Reynolds number pressure-driven flow are investigated numerically using an axisymmetric boundary element method. This fluid-structure interaction problem is determined by three dimen-sionless parameters: reduced volume (a measure of the vesicle asphericity), geometric confinement (the ratio of the vesicle effective radius to the tube radius), and capillary number (the ratio of viscous to bending forces). The physical constraints of a vesicle--fixed surface area and enclosed volume when it is confined in a tube--determine critical confinement beyond which it cannot pass through without rupturing its membrane. The simulated results are presented in a wide range of reduced volumes [0.6, 0.98] for different degrees of confinement; the reduced volume of 0.6 mimics red blood cells. We draw a phase diagram of vesicle shapes and propose a shape transition line separating the parachutelike shape region from the bulletlike one in the reduced volume versus confinement phase space. We show that the shape transition marks a change in the behavior of vesicle mobility, especially for highly deflated vesicles. Most importantly, high-resolution simulations make it possible for us to examine the hydrodynamic interaction between the wall boundary and the vesicle surface at conditions of very high confinement, thus providing the limiting behavior of several quantities of interest, such as the thickness of lubrication film, vesicle mobility and its length, and the extra pressure drop due to the presence of the vesicle. This extra pressure drop holds implications for the rheology of dilute vesicle suspensions. Furthermore, we present various correlations and discuss a number of practical applications. The results of this work may serve as a benchmark for future studies and help devise tube-flow experiments.
Paul G. Chen, J M Lyu, M Jaeger, M. Leonetti. Shape transition and hydrodynamics of vesicles in tube flow. Physical Review Fluids, 2020, 5 (4), pp.043602. ⟨10.1103/PhysRevFluids.5.043602⟩. ⟨hal-02415320v2⟩
Dry granular material flowing on rough inclines can experience a self-induced Rayleigh-Taylor (RT) instability followed by the spontaneous emergence of convection cells. For this to happen, particles are different in size and density, the larger particles are the denser but still segregate toward the surface. When the flow is, as usual, initially made of two layers, dense particles above, a Rayleigh-Taylor instability develops during the flow. When the flow is initially made of one homogeneous layer mixture, the granular segregation leads to the formation of an unstable layer of large-dense particles at the surface which subsequently destabilizes in a RT plume pattern. The unstable density gradient has been only induced by the motion of the granular matter. This self-induced Rayleigh-Taylor instability and the two-layer RT instability are studied using two different methods, experiments and simulations. At last, contrarily to the usual fluid behavior where the RT instability relaxes into two superimposed stable layers of fluid, the granular flow evolves to a pattern of alternated bands corresponing to recirculation cells analogous to Rayleigh-Bénard convection cells where segregation sustains the convective motion.
Wenjun Liu, Paul G. Chen, Jalil Ouazzani, Qiusheng Liu. Thermocapillary flow transition in an evaporating liquid layer in a heated cylindrical cell. International Journal of Heat and Mass Transfer, 2020, 153, pp.119587. ⟨10.1016/j.ijheatmasstransfer.2020.119587⟩. ⟨hal-02488876⟩ Plus de détails...
Motived by recent ground-based and microgravity experiments investigating the interfacial dynamics of a volatile liquid (FC-72, P r = 12.34) contained in a heated cylindrical cell, we numerically study the thermocapillary-driven flow in such an evaporating liquid layer. Particular attention is given to the prediction of the transition of the axisymmetric flow to fully three-dimensional patterns when the applied temperature increases. The numerical simulations rely on an improved one-sided model of evaporation by including heat and mass transfer through the gas phase via the heat transfer Biot number and the evaporative Biot number. We present the axisymmetric flow characteristics, show the variation of the transition points with these Biot numbers, and more importantly elucidate the twofold role of the latent heat of evaporation in the stability; evaporation not only destabilizes the flow but also stabilizes it, depending upon the place where the evaporation-induced thermal gradients come into play. We also show that buoyancy in the liquid layer has a stabilizing effect, though its effect is insignificant. At high Marangoni numbers, the numerical simulations revealed smaller-scale thermal patterns formed on the surface of a thinner evaporating layer, in qualitative agreement with experimental observations. The present work helps to gain a better understanding of the role of a phase change in the thermocapillary instability of an evaporating liquid layer.
Wenjun Liu, Paul G. Chen, Jalil Ouazzani, Qiusheng Liu. Thermocapillary flow transition in an evaporating liquid layer in a heated cylindrical cell. International Journal of Heat and Mass Transfer, 2020, 153, pp.119587. ⟨10.1016/j.ijheatmasstransfer.2020.119587⟩. ⟨hal-02488876⟩
Journal: International Journal of Heat and Mass Transfer
The lattice Boltzmann method often involves small numerical time steps due to the acoustic scaling (i.e., scaling between time step and grid size) inherent to the method. In this work, a second-order dual-time-stepping lattice Boltzmann method is proposed in order to avoid any time-step restriction. The implementation of the dual time stepping is based on an external source in the lattice Boltzmann equation, related to the time derivatives of the macroscopic flow quantities. Each time step is treated as a pseudosteady problem. The convergence rate of the steady lattice Boltzmann solver is improved by implementing a multigrid method. The developed solver is based on a two-relaxation time model coupled to an immersed-boundary method. The reliability of the method is demonstrated for steady and unsteady laminar flows past a circular cylinder, either fixed or towed in the computational domain. In the steady-flow case, the multigrid method drastically increases the convergence rate of the lattice Boltzmann method. The dual-time-stepping method is able to accurately reproduce the unsteady flows. The physical time step can be freely adjusted; its effect on the simulation cost is linear, while its impact on the accuracy follows a second-order trend. Two major advantages arise from this feature. (i) Simulation speed-up can be achieved by increasing the time step while conserving a reasonable accuracy. A speed-up of 4 is achieved for the unsteady flow past a fixed cylinder, and higher speed-ups are expected for configurations involving slower flow variations. Significant additional speed-up can also be achieved by accelerating transients. (ii) The choice of the time step allows us to alter the range of simulated timescales. In particular, increasing the time step results in the filtering of undesired pressure waves induced by sharp geometries or rapid temporal variations, without altering the main flow dynamics. These features may be critical to improve the efficiency and range of applicability of the lattice Boltzmann method.
Simon Gsell, Umberto d'Ortona, Julien Favier. Multigrid dual-time-stepping lattice Boltzmann method. Physical Review E , 2020, 101 (2), ⟨10.1103/PhysRevE.101.023309⟩. ⟨hal-02573156⟩
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, Elsevier, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩ Plus de détails...
A novel methodology is developed for predicting the thermal impact of fouling in Steam Generators (SG). The originality of this methodology is to resort to fractal and statistical theories to depict the porous structure of the deposits. The proposed Statistical Fractal methodology (SF) accounts for the heat transfer driven by the liquid-vapor phase change inside the deposits. It simulates the complex intricate networks of sinuous open pores of different scales, with liquid inflows (capillaries) and vapor outflows (steam-chimneys). The multi-layered representation of fouling deposits allows to mimic aging mechanisms such as densification which occur during SG operation. The SF predictions are consistent with experimental data. The deposit thickness and the profile of porosity are found to be the most influential fouling properties on the heat exchange. The methodology is capable to simulate the experimentally observed heat transfer enhancement for thin and porous deposit as well as the heat exchange decline for thick and dense deposit.
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, Elsevier, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩
Journal: International Journal of Heat and Mass Transfer
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩ Plus de détails...
A novel methodology is developed for predicting the thermal impact of fouling in Steam Generators (SG). The originality of this methodology is to resort to fractal and statistical theories to depict the porous structure of the deposits. The proposed Statistical Fractal methodology (SF) accounts for the heat transfer driven by the liquid-vapor phase change inside the deposits. It simulates the complex intricate networks of sinuous open pores of different scales, with liquid inflows (capillaries) and vapor outflows (steam-chimneys). The multi-layered representation of fouling deposits allows to mimic aging mechanisms such as densification which occur during SG operation.The SF predictions are consistent with experimental data. The deposit thickness and the profile of porosity are found to be the most influential fouling properties on the heat exchange. The methodology is capable to simulate the experimentally observed heat transfer enhancement for thin and porous deposit as well as the heat exchange decline for thick and dense deposit.
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩
Journal: International Journal of Heat and Mass Transfer
The coordinated beating of epithelial cilia in human lungs is a fascinating problem from the hydrodynamics perspective. The phase lag between neighboring cilia is able to generate collective cilia motions, known as metachronal waves. Different kinds of waves can occur, antiplectic or symplectic, depending on the direction of the wave with respect to the flow direction. It is shown here, using a coupled lattice Boltzmann-immersed boundary solver, that the key mechanism responsible for their transport efficiency is a blowing-suction effect that displaces the interface between the periciliary liquid and the mucus phase. The contribution of this mechanism on the average flow generated by the cilia is compared to the contribution of the lubrication effect. The results reveal that the interface displacement is the main mechanism responsible for the better efficiency of antiplectic metachronal waves over symplectic ones to transport bronchial mucus. The conclusions drawn here can be extended to any two-layer fluid configuration having different viscosities, and put into motion by cilia-shaped or comb-plate structures, having a back-and-forth motion with phase lags.
Sylvain Chateau, Julien Favier, Sébastien Poncet, Umberto d'Ortona. Why antiplectic metachronal cilia waves are optimal to transport bronchial mucus. Physical Review E , 2019, 100 (4), pp.042405. ⟨10.1103/PhysRevE.100.042405⟩. ⟨hal-02468006⟩
Simon Gsell, Umberto d'Ortona, Julien Favier. Explicit and viscosity-independent immersed-boundary scheme for the lattice Boltzmann method. Physical Review E , 2019, 100 (3), ⟨10.1103/PhysRevE.100.033306⟩. ⟨hal-02339475⟩ Plus de détails...
Viscosity independence of lattice-Boltzmann methods is a crucial issue to ensure the physical relevancy of the predicted macroscopic flows over large ranges of physical parameters. The immersed-boundary (IB) method, a powerful tool that allows one to immerse arbitrary-shaped, moving, and deformable bodies in the flow, suffers from a boundary-slip error that increases as a function of the fluid viscosity, substantially limiting its range of application. In addition, low fluid viscosities may result in spurious oscillations of the macroscopic quantities in the vicinity of the immersed boundary. In this work, it is shown mathematically that the standard IB method is indeed not able to reproduce the scaling properties of the macroscopic solution, leading to a viscosity-related error on the computed IB force. The analysis allows us to propose a simple correction of the IB scheme that is local, straightforward and does not involve additional computational time. The derived method is implemented in a two-relaxation-time D2Q9 lattice-Boltzmann solver, applied to several physical configurations, namely, the Poiseuille flow, the flow around a cylinder towed in still fluid, and the flow around a cylinder oscillating in still fluid, and compared to a noncorrected immersed-boundary method. The proposed correction leads to a major improvement of the viscosity independence of the solver over a wide range of relaxation times (from 0.5001 to 50), including the correction of the boundary-slip error and the suppression of the spurious oscillations. This improvement may considerably extend the range of application of the IB lattice-Boltzmann method, in particular providing a robust tool for the numerical analysis of physical problems involving fluids of varying viscosity interacting with solid geometries.
Simon Gsell, Umberto d'Ortona, Julien Favier. Explicit and viscosity-independent immersed-boundary scheme for the lattice Boltzmann method. Physical Review E , 2019, 100 (3), ⟨10.1103/PhysRevE.100.033306⟩. ⟨hal-02339475⟩
C. Lebrun, S. Vukusic, V. Abadie, C. Achour, F. Ader, et al.. Immunization and multiple sclerosis: Recommendations from the French Multiple Sclerosis Society. Revue Neurologique, Elsevier Masson, 2019, 175 (6), pp.341-357. ⟨10.1016/j.neurol.2019.04.001⟩. ⟨hal-02546158⟩ Plus de détails...
Objectives: To establish recommendations on immunization for patients with multiple sclerosis (MS).Background: Vaccines have been suspected in the past to trigger MS and relapses. With the extension of the immunoactive treatment arsenal, other concerns have been raised more recently about an increased risk of infection or a decreased effectiveness of immunization in immunosuppressed patients.Methods: The French Group for Recommendations into Multiple Sclerosis (France4MS) performed a systematic search of papers in Medline and other university databases (January 1975-June 2018). The RAND/UCLA appropriateness method was chosen to review the scientific literature and to formalize the degree of agreement among experts on 5 clinical questions related to immunization and MS. Readers from the steering committee conducted a systematic analysis, wrote a critical synthesis and prepared a list of proposals that were evaluated by a rating group of 28 MS experts. The final version of the recommendations was finally reviewed by a reading group of 110 health care professionals and classified as appropriate, inappropriate or uncertain.Results: Neurologists should verify the vaccination status as soon as MS is diagnosed and before disease-modifying treatments (DMTs) are introduced. The French vaccination schedule applies to MS patients and seasonal influenza vaccination is recommended. In the case of treatment-induced immunosuppression, MS patients should be informed about the risk of infection and the vaccination standards of the French High Council of Health should be applied. Live attenuated vaccines are contra-indicated in patients recently treated with immunosuppressive drugs, including corticosteroids; other vaccines can be proposed whatever the treatment, but their effectiveness may be partly reduced with some drugs.Conclusion: Physicians and patients should be aware of the updated recommendations for immunizations of patients with MS.
C. Lebrun, S. Vukusic, V. Abadie, C. Achour, F. Ader, et al.. Immunization and multiple sclerosis: Recommendations from the French Multiple Sclerosis Society. Revue Neurologique, Elsevier Masson, 2019, 175 (6), pp.341-357. ⟨10.1016/j.neurol.2019.04.001⟩. ⟨hal-02546158⟩
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, 2019, Application of Membrane Filtration in Industrial Processes, and in the Treatment of Water and Industrial Wastewater), 9 (4), pp.48. ⟨10.3390/membranes9040048⟩. ⟨hal-02109009⟩ Plus de détails...
In cross-flow membrane filtration, fouling results from material deposit which clogs the membrane inner surface. This hinders filtration, which experiences the so-called limiting flux. Among the models proposed by the literature, we retain a simple one: a steady-state reversible fouling is modelled with the use of a single additional parameter, i.e., N d , the ratio of the critical concentration for deposition to the feed concentration at inlet. To focus on fouling, viscous pressure drop and osmotic (counter-)pressure have been chosen low. It results in a minimal model of fouling. Solved thoroughly with the numerical means appropriate to enforce the nonlinear coupling between permeation and concentration polarization, the model delivers novel information. It first shows that permeation is utterly governed by solute transfer, the relevant non-dimensional quantities being hence limited to N d and Pe in , the transverse Péclet number. Furthermore, when the role played by N d and moderate Pe in (say Pe in < 40) is investigated, all results can be interpreted with the use of a single non-dimensional parameter, F l , the so-called fouling number, which simply reads F l ≡ Pe in N −1 d. Now rendered possible, the overall fit of the numerical data allows us to put forward analytical final expressions, which involve all the physical parameters and allow us to retrieve the experimental trends.
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, 2019, Application of Membrane Filtration in Industrial Processes, and in the Treatment of Water and Industrial Wastewater), 9 (4), pp.48. ⟨10.3390/membranes9040048⟩. ⟨hal-02109009⟩
Carlos Baqueiro, Nelson Ibaseta, Pierrette Guichardon, Laurent Falk. Influence of reagents choice (buffer, acid and inert salt) on triiodide production in the Villermaux–Dushman method applied to a stirred vessel. Chemical Engineering Research and Design, 2018, 136, pp.25-31. ⟨10.1016/j.cherd.2018.04.017⟩. ⟨hal-01771934⟩ Plus de détails...
This work studies how deeply the reagents choice influences micromixing characterisation by the Villermaux-Dushman method, when applying it to a 1 litre stainless steel standard vessel with two baffles, stirred by an inclined blade turbine. For the first time, borate and phosphate buffer are compared on their use in the method. It is observed that triiodide production is higher when borate buffer is used. Moreover, perchloric acid leads to higher triiodide production than sulphuric acid, when injecting the same concentration of both acids. Finally, the influence of the ionic strength is also studied, since there has been a great deal of controversy about it over the last years. The results show that the ionic strength affects triiodide production, although relatively slightly. Advice concerning the choice of the reagents is given in conclusion.
Carlos Baqueiro, Nelson Ibaseta, Pierrette Guichardon, Laurent Falk. Influence of reagents choice (buffer, acid and inert salt) on triiodide production in the Villermaux–Dushman method applied to a stirred vessel. Chemical Engineering Research and Design, 2018, 136, pp.25-31. ⟨10.1016/j.cherd.2018.04.017⟩. ⟨hal-01771934⟩
Xue Chen, Xun Wang, Paul G. Chen, Qiusheng Liu. Determination of Diffusion Coefficient in Droplet Evaporation Experiment Using Response Surface Method. Microgravity Science and Technology, 2018, 30, pp.675-682. ⟨10.1007/s12217-018-9645-2⟩. ⟨hal-02112826⟩ Plus de détails...
Evaporation of a liquid droplet resting on a heated substrate is a complex free-surface advection-diffusion problem, in which the main driving force of the evaporation is the vapor concentration gradient across the droplet surface. Given the uncertainty associated with the diffusion coefficient of the vapor in the atmosphere during space evaporation experiments due to the environmental conditions, a simple and accurate determination of its value is of paramount importance for a better understanding of the evaporation process. Here we present a novel approach combining numerical simulations and experimental results to address this issue. Specifically, we construct a continuous function of output using a Kriging-based response surface method, which allows to use the numerical results as a black-box with a limited number of inputs and outputs. Relevant values of the diffusion coefficient can then be determined by solving an inverse problem which is based on accessible experimental data and the proposed response surface. In addition, on the basis of our numerical simulation results, we revisit a widely used formula for the prediction of the evaporation rate in the literature and propose a refined expression for the droplets evaporating on a heated substrate.
Xue Chen, Xun Wang, Paul G. Chen, Qiusheng Liu. Determination of Diffusion Coefficient in Droplet Evaporation Experiment Using Response Surface Method. Microgravity Science and Technology, 2018, 30, pp.675-682. ⟨10.1007/s12217-018-9645-2⟩. ⟨hal-02112826⟩
Jinming Lyu, Paul G. Chen, Gwenn Boedec, Marc Leonetti, Marc Jaeger. Hybrid continuum–coarse-grained modeling of erythrocytes. Comptes Rendus Mécanique, 2018, 346, pp.439-448. ⟨10.1016/j.crme.2018.04.015⟩. ⟨hal-01785429⟩ Plus de détails...
The red blood cell (RBC) membrane is a composite structure, consisting of a phospholipid bilayer and an underlying membrane-associated cytoskeleton. Both continuum and particle-based coarse-grained RBC models make use of a set of vertices connected by edges to represent the RBC membrane, which can be seen as a triangular surface mesh for the former and a spring network for the latter. Here, we present a modeling approach combining an existing continuum vesicle model with a coarse-grained model for the cytoskeleton. Compared to other two-component approaches, our method relies on only one mesh, representing the cytoskeleton, whose velocity in the tangential direction of the membrane may be different from that of the lipid bilayer. The finitely extensible nonlinear elastic (FENE) spring force law in combination with a repulsive force defined as a power function (POW), called FENE-POW, is used to describe the elastic properties of the RBC membrane. The mechanical interaction between the lipid bilayer and the cytoskeleton is explicitly computed and incorporated into the vesicle model. Our model includes the fundamental mechanical properties of the RBC membrane, namely fluidity and bending rigidity of the lipid bilayer, and shear elasticity of the cytoskeleton while maintaining surface-area and volume conservation constraint. We present three simulation examples to demonstrate the effectiveness of this hybrid continuum--coarse-grained model for the study of RBCs in fluid flows.
Jinming Lyu, Paul G. Chen, Gwenn Boedec, Marc Leonetti, Marc Jaeger. Hybrid continuum–coarse-grained modeling of erythrocytes. Comptes Rendus Mécanique, 2018, 346, pp.439-448. ⟨10.1016/j.crme.2018.04.015⟩. ⟨hal-01785429⟩
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , 2018, 97 (5). ⟨hal-02001973⟩ Plus de détails...
To better understand the velocity field and flowing layer structure, we have performed a detailed discrete element method study of the flow of monodisperse particles in a partially filled three-dimensional cylindrical rotating tumblers. Similar to what occurs near the poles in spherical and conical tumblers, recirculation cells (secondary flows) develop near the flat endwalls of a cylindrical tumbler in which particles near the surface drift axially toward the endwall, while particles deeper in the flowing layer drift axially toward the midlength of the tumbler. Another recirculation cell with the opposite sense develops next to each endwall recirculation cell, extending to the midlength of the tumbler. For a long enough tumbler, each endwall cell is about one quarter of the tumbler diameter in length. Endwall cells are insensitive to tumbler length and relatively insensitive to rotation speed (so long as the flowing layer remains flat and continuously flowing) or fill level (from 25% to 50% full). However, for shorter tumblers (0.5 to 1.0 length/diameter aspect ratio) the endwall cell size does not change much, while center cells reduce their size and eventually disappear for the shortest tumblers. For longer tumblers (length/diameter aspect ratio larger than 2), a stagnation zone appears in between the central cells. These results provide insight into the mixing of monodisperse particles in rotating cylindrical tumblers as well as the frictional effects of the tumbler endwalls.
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , 2018, 97 (5). ⟨hal-02001973⟩
Sylvain Chateau, Umberto d'Ortona, Sébastien Poncet, Julien Favier. Transport and Mixing Induced by Beating Cilia in Human Airways. Frontiers in Physiology, 2018, 9, pp.161. ⟨10.3389/fphys.2018.00161⟩. ⟨hal-01875672⟩ Plus de détails...
The fluid transport and mixing induced by beating cilia, present in the bronchial airways, are studied using a coupled lattice Boltzmann-Immersed Boundary solver. This solver allows the simulation of both single and multi-component fluid flows around moving solid boundaries. The cilia aremodeled by a set of Lagrangian points, and Immersed Boundary forces are computed onto these points in order to ensure the no-slip velocity conditions between the cilia and the fluids. The cilia are immersed in a two-layer environment: the periciliary layer (PCL) and the mucus above it. The motion of the cilia is prescribed, as well as the phase lag between two cilia in order to obtain a typical collective motion of cilia, known as metachronal waves. The results obtained from a parametric study show that antiplectic metachronal waves are the most efficient regarding the fluid transport. A specific value of phase lag, which generates the larger mucus transport, is identified. The mixing is studied using several populations of tracers initially seeded into the pericilary liquid, in the mucus just above the PCL-mucus interface, and in the mucus far away from the interface. We observe that each zone exhibits different chaotic mixing properties. The larger mixing is obtained in the PCL layer where only a few beating cycles of the cilia are required to obtain a full mixing, while above the interface, the mixing is weaker and takes more time. Almost no mixing is observed within the mucus, and almost all the tracers do not penetrate the PCL layer. Lyapunov exponents are also computed for specific locations to assess how the mixing is performed locally. Two time scales are introduced to allow a comparison between mixing induced by fluid advection and by molecular diffusion. These results are relevant in the context of respiratory flows to investigate the transport of drugs for patients suffering from chronic respiratory diseases.
Sylvain Chateau, Umberto d'Ortona, Sébastien Poncet, Julien Favier. Transport and Mixing Induced by Beating Cilia in Human Airways. Frontiers in Physiology, 2018, 9, pp.161. ⟨10.3389/fphys.2018.00161⟩. ⟨hal-01875672⟩
Gustavo Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Effects of solute permeability on permeation and solute rejection in membrane filtration. Chemical Engineering and Technology, 2018, 41 (4), pp.788-797. ⟨10.1002/ceat.201700203⟩. ⟨hal-01681108⟩ Plus de détails...
Membrane solute permeability plays a role in the buildup of concentration polarization in pressure-driven crossflow filtration processes, and thus in the determination of the permeate flux, solute rejection, retentate flux and concentration. We numerically examine reverse-osmosis desalination with membranes of fixed solvent permeability, but of variable selectivity with respect to the solute. The study highlights an intricate coupling between retentate and filtrate properties. In particular, it reveals that, for given values of solute permeability and feed concentration, there is a maximum operating pressure that optimizes solute rejection regardless of the feed salinity. The conditions leading to this and to other peculiar behaviors for permeation fluxes and concentrations are identified.
Gustavo Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Effects of solute permeability on permeation and solute rejection in membrane filtration. Chemical Engineering and Technology, 2018, 41 (4), pp.788-797. ⟨10.1002/ceat.201700203⟩. ⟨hal-01681108⟩
Mustapha-Kamel Khelloufi, Etienne Loiseau, Marc Jaeger, Nicolas Molinari, Pascal Chanez, et al.. Spatiotemporal organization of cilia drives multiscale mucus swirls in model human bronchial epithelium. Scientific Reports, 2018, 8, pp.2447. ⟨10.1038/s41598-018-20882-4⟩. ⟨hal-01821276⟩ Plus de détails...
Mucociliary clearance is a biomechanical mechanism of airway protection. It consists of the active transport along the bronchial tree of the mucus, a fluid propelled by the coordinated beating of a myriad of cilia on the epithelial surface of the respiratory tract. The physics of mucus transport is poorly understood because it involves complex phenomena such as long-range hydrodynamic interactions, active collective ciliary motion, and the complex rheology of mucus. We propose a quantitative physical analysis of the ciliary activity and mucus transport on a large panel of human bronchial cultures from control subjects, patients with asthma and chronic obstructive pulmonary disease obtained from endobronchial biopsies. Here we report on the existence of multiple ciliary domains with sizes ranging from the tens of a micron to the centimeter, where ciliary beats present a circular orientational order. These domains are associated with circular mucus flow patterns, whose size scales with the average cilia density. In these domains, we find that the radial increase of the ciliated cell density coupled with the increase in the orientational order of ciliary beats result in a net local force proportional to the mucus velocity. We propose a phenomenological physical model that supports our results.
Mustapha-Kamel Khelloufi, Etienne Loiseau, Marc Jaeger, Nicolas Molinari, Pascal Chanez, et al.. Spatiotemporal organization of cilia drives multiscale mucus swirls in model human bronchial epithelium. Scientific Reports, 2018, 8, pp.2447. ⟨10.1038/s41598-018-20882-4⟩. ⟨hal-01821276⟩
Henri Gouin, Pierre Seppecher. Temperature profile in a liquid-vapor interface near the critical point. Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences, 2017, 473 (20170229), pp.1-13. ⟨10.1098/rspa.2017.0229⟩. ⟨hal-01492802v2⟩ Plus de détails...
Thanks to an expansion with respect to densities of energy, mass and entropy, we discuss the concept of thermocapillary fluid for inhomogeneous fluids. The non-convex state law valid for homogeneous fluids is modified by adding terms taking account of the gradients of these densities. This seems more realistic than Cahn and Hilliard's model which uses a density expansion in mass-density gradient only. Indeed, through liquid-vapor interfaces, realistic potentials in molecular theories show that entropy density and temperature do not vary with the mass density as it would do in bulk phases. In this paper, we prove using a rescaling process near the critical point that liquid-vapor interfaces behave essentially in the same way as in Cahn and Hilliard's model.
Henri Gouin, Pierre Seppecher. Temperature profile in a liquid-vapor interface near the critical point. Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences, 2017, 473 (20170229), pp.1-13. ⟨10.1098/rspa.2017.0229⟩. ⟨hal-01492802v2⟩
Journal: Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences
Gwenn Boedec, Marc Leonetti, Marc Jaeger. Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow. Journal of Computational Physics, 2017, 342, pp.117 - 138. ⟨10.1016/j.jcp.2017.04.024⟩. ⟨hal-01590257⟩ Plus de détails...
We develop an algorithm for the three dimensional simulation of the dynamics of soft objects (drops, capsules, vesicles) under creeping flow conditions. Loop elements are used to describe the shape of the soft objects. This surface representation is used both for membrane solver based on finite element method (FEM) and for the fluid solver based on the boundary element method (BEM). This isogeometric analysis of the low Reynolds fluid-structure interaction problem is then coupled to high-order explicit time stepping or second-order implicit time stepping algorithm. For vesicles simulation, a preconditioner is designed for the resolution of the surface velocity incompressibility constraint, which is treated by the use of a local Lagrange multiplier. A mesh quality preserving algorithm is introduced to improve the control mesh quality over long simulation times. We test the proposed algorithm on capsule and vesicle dynamics in various flows, and study its convergence properties, showing a second-order convergence O(N-2) with mesh number of elements.
Gwenn Boedec, Marc Leonetti, Marc Jaeger. Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow. Journal of Computational Physics, 2017, 342, pp.117 - 138. ⟨10.1016/j.jcp.2017.04.024⟩. ⟨hal-01590257⟩
Xue Chen, Xun Wang, Paul G. Chen, Qiusheng Liu. Thermal effects of substrate on Marangoni flow in droplet evaporation: Response surface and sensitivity analysis. International Journal of Heat and Mass Transfer, 2017, 113, pp.354 - 365. ⟨10.1016/j.ijheatmasstransfer.2017.05.076⟩. ⟨hal-01532757⟩ Plus de détails...
In this paper, the evaporation of sessile droplets resting on a substrate with different thermal properties is numerically investigated. Computations are based on a transient axisymmetric numerical model. Special attention is paid to evaluate thermal effects of substrate on the structure of bulk fluid flow in the course of evaporation. Numerical results reveal that Marangoni convection induced by non-uniform distribution of temperature along the interface exhibits three distinctly different behaviours: inward flow, multicellular flow and outward flow, consequently resulting in different particle depositions. It is highlighted that three factors (i.e. relative thermal conductivity, relative substrate thickness and relative substrate temperature) strongly affect the flow pattern. In order to further investigate the coupling effects of different influential factors, a Kriging-based response surface method is introduced. We model the flow behaviour as a function of continuous influential factors using a limited number of computations corresponding to discrete values of the inputs. The sensitivities of the Marangoni flow are also analysed using Sobol’ index to study the coupling mechanisms of influential factors. The proposed method can be used to forecast the flow patterns for any input parameter without additional sophisticated computer simulation, and allows to confidently estimate an unknown environmental parameter.
Xue Chen, Xun Wang, Paul G. Chen, Qiusheng Liu. Thermal effects of substrate on Marangoni flow in droplet evaporation: Response surface and sensitivity analysis. International Journal of Heat and Mass Transfer, 2017, 113, pp.354 - 365. ⟨10.1016/j.ijheatmasstransfer.2017.05.076⟩. ⟨hal-01532757⟩
Journal: International Journal of Heat and Mass Transfer
Xue Chen, Paul G. Chen, Jalil Ouazzani, Qiusheng Liu. Numerical simulations of sessile droplet evaporating on heated substrate. The European Physical Journal. Special Topics, 2017, 226 (6), pp.1325-1335. ⟨10.1140/epjst/e2016-60203-y⟩. ⟨hal-01509843⟩ Plus de détails...
Motivated by the space project EFILE, a 2D axisymmetric numerical model in the framework of ALE method is developed to investigate the coupled physical mechanism during the evaporation of a pinned drop that partially wets on a heated substrate. The model accounts for mass transport in surrounding air, Marangoni convection inside the drop and heat conduction in the substrate as well as moving interface. Numerical results predict simple scaling laws for the evaporation rate which scales linearly with drop radius but follows a power-law with substrate temperature. It is highlighted that thermal effect of the substrate has a great impact on the temperature profile at the drop surface, which leads to a multicellular thermocapillary flow pattern. In particular, the structure of the multicellular flow behavior induced within a heated drop is mainly controlled by a geometric parameter (aspect ratio). A relationship between the number of thermal cells and the aspect ratio is proposed。
Xue Chen, Paul G. Chen, Jalil Ouazzani, Qiusheng Liu. Numerical simulations of sessile droplet evaporating on heated substrate. The European Physical Journal. Special Topics, 2017, 226 (6), pp.1325-1335. ⟨10.1140/epjst/e2016-60203-y⟩. ⟨hal-01509843⟩
Journal: The European Physical Journal. Special Topics
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, 2017, 404, pp.341 - 359. ⟨10.1016/j.desal.2016.09.026⟩. ⟨hal-01405589⟩ Plus de détails...
An accurate 2-D numerical model that accounts for concentration polarization and osmotic effects is developed for the cross-flow filtration in a membrane channel. Focused on the coupling between laminar hydrodynam-ics and mass transfer, the numerical approach solves the solute conservation equation together with the steady Navier-Stokes equations under the Prandtl approximation, which offers a simplified framework to enforce the non-linear coupling between filtration and concentration polarization at the membrane surface. The present approach is first validated thanks to the comparison with classical exact analytical solutions for hydrodynamics and/or mass transfer, as well as with approximated analytical solutions that attempted at coupling the various phenomena. The effects of the main parameters in cross-flow reverse osmosis (RO) or nanofiltration (NF) (feed concentration, axial flow rate, operating pressure and membrane permeability) on streamlines, velocity profile, longitudinal pressure drop, local permeate flux and solute concentration profile are predicted with the present numerical model, and discussed. With the use of data reported from NF and RO experiments, the Prandtl approximation model is shown to accurately correlate both average permeate flux and local solute concentration over a wide range of operating conditions.
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, 2017, 404, pp.341 - 359. ⟨10.1016/j.desal.2016.09.026⟩. ⟨hal-01405589⟩
E Alekseenko, B Roux, D Fougere, Paul G. Chen. The effect of wind induced bottom shear stress and salinity on Zostera noltii replanting in a Mediterranean coastal lagoon. Estuarine, Coastal and Shelf Science, 2017, 187, pp.293-305. ⟨10.1016/j.ecss.2017.01.010⟩. ⟨hal-01453377⟩ Plus de détails...
The paper concerns the wind influence on bottom shear stress and salinity levels in a Mediterranean semi-enclosed coastal lagoon (Etang de Berre), with respect to a replanting program of Zostera noltii . The MARS3D numerical model is used to analyze the 3D current, salinity and temperature distribution induced by three meteorological, oceanic and anthropogenic forcings in this lagoon. The numerical model has been carefully validated by comparison with daily observations of the vertical salinity and temperature profiles at three mooring stations, for one year. Then, two modelling scenarios are considered. The first scenario (scen.## 1), starting with an homogeneous salinity of S = 20 PSU and without wind forcing, studies a stratification process under the influence of a periodic seawater inflow and a strong freshwater inflow from an hydropower plant (250 m3/s). Then, in the second scenario (scen.## 2), we study how a strong wind of 80 km/h can mix the haline stratification obtained at the end of scen.## 1. The most interesting results concern four nearshore replanting areas; two are situated on the eastern side of EB and two on the western side. The results of scen.## 2 show that all these areas are subject to a downwind coastal jet. Concerning bottom salinity, the destratification process is very beneficial; it always remains greater than 12 PSU for a N-NW wind of 80 km/h and an hydropower runoff of 250 m3/s. Special attention is devoted to the bottom shear stress (BSS) for different values of the bottom roughness parameter (for gravels, sands and silts), and to the bottom salinity. Concerning BSS, it presents a maximum near the shoreline and decreases along transects perpendicular to the shoreline. There exists a zone, parallel to the shoreline, where BSS presents a minimum (close to zero). When comparing the BSS value at the four replanting areas with the critical value, BSScr, at which the sediment mobility would occur, we see that for the smaller roughness values (ranging from z0 = 3.5 × 10-4 mm, to 3.5 × 10-2 mm) BSS largely surpasses this critical value. For a N-NW wind speed of 40 km/h (which is blowing for around 100 days per year), BSS still largely surpasses BSScr - at least for the silt sediments (ranging from z0 = 3.5 × 10-4 mm, to 3.5 × 10-3 mm). This confirms the possibility that the coastal jet could generate sediment mobility which could have a negative impact for SAV replanting.
E Alekseenko, B Roux, D Fougere, Paul G. Chen. The effect of wind induced bottom shear stress and salinity on Zostera noltii replanting in a Mediterranean coastal lagoon. Estuarine, Coastal and Shelf Science, 2017, 187, pp.293-305. ⟨10.1016/j.ecss.2017.01.010⟩. ⟨hal-01453377⟩
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Axial segregation in spherical and cylindrical rotating tumblers. EPJ Web of Conferences, 2017, Powders and Grains 2017 – 8th International Conference on Micromechanics on Granular Media, 140, pp.03011. ⟨10.1051/epjconf/201714003011⟩. ⟨hal-01671207⟩ Plus de détails...
Monodisperse and bidisperse granular flows are studied in rotating tumblers using DEM. In spherical tumblers, flowing particles’ trajectories do not follow straight lines but are curved. At the same time particles near the surface drift toward the pole, inducing two global recirculation cells. Combined with radial segregation, drift and curvature compete to impose the axial segregation pattern: Small-Large-Small (SLS) or Large-Small-Large (LSL). Fill level, rotation speed and wall roughness influence drift and curvature, and modify the resulting segregation pattern. In cylindrical tumblers, equivalent recirculation cells occur next to the end walls. A second pair of recirculation cells with a weak drift in the opposite direction appears at the center for long enough tumblers. Unlike the sphere case, curvature and drift in the primary cells combine to push large particles toward the end walls, explaining why large particle bands appear at the end walls for axial segregation in cylinder.
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Axial segregation in spherical and cylindrical rotating tumblers. EPJ Web of Conferences, 2017, Powders and Grains 2017 – 8th International Conference on Micromechanics on Granular Media, 140, pp.03011. ⟨10.1051/epjconf/201714003011⟩. ⟨hal-01671207⟩
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩ Plus de détails...
Tuning the mechanical properties of microcapsules with cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step. This thorough study provides new insights in the mechanics of these weakly cohesive membranes. Firstly, sus-pensions of water-in-oil microcapsules were formed in microfluidic junctions by self-assembling of two oppositely charged polyelectrolytes, namely chitosan (water soluble) and phosphatidic fatty acid (oil soluble). In this way, composite membranes of tunable thickness (between 40-900 nm measured by AFM) were formed at water / oil interfaces in a single step by changing the composition. Secondly, microcapsules were mechanically characterized by stretching them up to break-up in an extensional flow chamber which extends the relevance and convenience of the hydrodynamic method to weakly cohesive membranes. Finally, we show that the design of micro-capsules can be 'engineered' in a large way since they present a wealth of interfacial rheological properties in term of elasticity, plasticity and yield stress whose magnitudes can be controlled by the composition. These behaviors are explained by the variation of the membrane thickness with the physico-chemical parameters of the process.
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩
U. Laux, B. Stecklum, P. Bacci, M. Maestripieri, M. Carotta, et al.. 2017 OH7. Minor Planet Electronic Circulars, 2017. ⟨hal-02268848⟩ Plus de détails...
N. A. R. O. Nicolini Astronomical Robotic Observatory
K. Sárneczky
A. Ordasi
L. Hudin
L. Denneau
A. Heinze
H. Weiland
B. Stalder
J. Tonry
C. Jacques
E. Pimentel
J. Barros
G. Wells
J. Leuty
D. Bamberger
2017
Henri Gouin. Continuum mechanics at nanoscale. A tool to study trees' watering and recovery. Rendiconti Lincei. Matematica e Applicazioni, 2017, 28, pp.415-449. ⟨10.4171/RLM/769⟩. ⟨hal-01540964⟩ Plus de détails...
The cohesion-tension theory expounds the crude sap ascent thanks to the negative pressure generated by evaporation of water from leaves. Nevertheless, trees pose multiple challenges and seem to live in unphysical conditions: the negative pressure increases cavitation; it is possible to obtain a water equilibrium between connected parts where one is at a positive pressure and the other one is at negative pressure; no theory is able to satisfactorily account for the refilling of vessels after embolism events. A theoretical form of our paper in the Journal of Theoretical Biology is proposed together with new results: a continuum mechanics model of the disjoining pressure concept refers to the Derjaguin School of physical chemistry. A comparison between liquid behaviour both in tight-filled microtubes and in liquid thin-films is offered when the pressure is negative in liquid bulks and is positive in liquid thin-films and vapour bulks. In embolized xylem microtubes, when the air-vapour pocket pressure is greater than the air-vapour bulk pressure, a refilling flow occurs between the air-vapour domains to empty the air-vapour pockets although the liquid-bulk pressure remains negative. The model has a limit of validity taking the maximal size of trees into account. These results drop inkling that the disjoining pressure is an efficient tool to study biological liquids in contact with substrates at a nanoscale range.
Henri Gouin. Continuum mechanics at nanoscale. A tool to study trees' watering and recovery. Rendiconti Lincei. Matematica e Applicazioni, 2017, 28, pp.415-449. ⟨10.4171/RLM/769⟩. ⟨hal-01540964⟩
Journal: Rendiconti Lincei. Matematica e Applicazioni
Henri Gouin, Tommaso Ruggeri. Symmetric form for the hyperbolic-parabolic system of fourth-gradient fluid model. Ricerche di matematica, 2017, 66 (2), pp.491-508. ⟨10.1007/s11587-016-0315-7⟩. ⟨hal-01573721⟩ Plus de détails...
The fourth-gradient model for fluids-associated with an extended molecular mean-field theory of capillarity-is considered. By producing fluctuations of density near the critical point like in computational molecular dynamics, the model is more realistic and richer than van der Waals' one and other models associated with a second order expansion. The aim of the paper is to prove-with a fourth-gradient internal energy already obtained by the mean field theory-that the quasi-linear system of conservation laws can be written in an Hermitian symmetric form implying the stability of constant solutions. The result extends the symmetric hyperbolicity property of governing-equations' systems when an equation of energy associated with high order deformation of a continuum medium is taken into account.
Henri Gouin, Tommaso Ruggeri. Symmetric form for the hyperbolic-parabolic system of fourth-gradient fluid model. Ricerche di matematica, 2017, 66 (2), pp.491-508. ⟨10.1007/s11587-016-0315-7⟩. ⟨hal-01573721⟩
M. Dennefeld, W. Brzezinska, M. Nowak, F. Spoto, W. Thuillot, et al.. Comet P/2017 s5 (atlas). Minor Planet Electronic Circulars, 2017. ⟨hal-02268847⟩ Plus de détails...
Gustavo H. Lopes, Nelson Ibaseta, Pierrette Guichardon. How can osmosis and solute diffusion be coupled for the simultaneous measurement of the solvent and solute permeabilities of membranes?. Desalination, 2016, 387 (1), pp.61-74. ⟨10.1016/j.desal.2016.03.006⟩. ⟨hal-01290973⟩ Plus de détails...
A novel experimental method and its associated model are proposed for the simultaneous determination of membrane solute and solvent permeabilities, which are essential transport parameters of reverse osmosis models used for process simulation. The method utilizes a single bench-scale batch apparatus consisting of two stirred half-cells containing solutions of different concentrations separated by a membrane across which coupled non-steady-state solute diffusion and solvent osmosis take place countercurrently in the absence of transmembrane pressure difference. Results are presented from days-long determinations of the water and sodium chloride permeabilities of Filmtec BW30 and NF270 membrane samples for initial transmembrane salt concentration differences ranging from 1 g L-1 to 35 g L-1. When used as input parameters for the simulation of pilot reverse osmosis desalination tests, the osmotic-diffusive salt permeabilities approximated the experimental rejection rates.
Gustavo H. Lopes, Nelson Ibaseta, Pierrette Guichardon. How can osmosis and solute diffusion be coupled for the simultaneous measurement of the solvent and solute permeabilities of membranes?. Desalination, 2016, 387 (1), pp.61-74. ⟨10.1016/j.desal.2016.03.006⟩. ⟨hal-01290973⟩
J. Gounley, G. Boedec, Marc Jaeger, M. Leonetti. Influence of surface viscosity on droplets in shear flow. Journal of Fluid Mechanics, 2016, 791, pp.464- 494. ⟨10.1017/jfm.2016.39⟩. ⟨hal-01281643⟩ Plus de détails...
The behaviour of a single droplet in an immiscible external fluid, submitted to shear flow is investigated using numerical simulations. The surface of the droplet is modelled by a Boussinesq–Scriven constitutive law involving the interfacial viscosities and a constant surface tension. A numerical method using Loop subdivision surfaces to represent droplet interface is introduced. This method couples boundary element method for fluid flows and finite element method to take into account the stresses due to the surface dilational and shear viscosities and surface tension. Validation of the numerical scheme with respect to previous analytic and computational work is provided, with particular attention to the viscosity contrast and the shear and dilational viscosities characterized both by a Boussinesq number Bq. Then, influence of equal surface viscosities on steady-state characteristics of a droplet in shear flow are studied, considering both small and large deformations and for a large range of bulk viscosity contrast. We find that small deformation analysis is surprisingly predictive at moderate and high surface viscosities. Equal surface viscosities decrease the Taylor deformation parameter and tank-treading angle and also strongly modify the dynamics of the droplet: when the Boussinesq number (surface viscosity) is large relative to the capillary number (surface tension), the droplet displays damped oscillations prior to steady-state tank-treading, reminiscent from the behaviour at large viscosity contrast. In the limit of infinite capillary number Ca, such oscillations are permanent. The influence of surface viscosities on breakup is also investigated, and results show that the critical capillary number is increased. A diagram (Bq;Ca) of breakup is established with the same inner and outer bulk viscosities. Additionally, the separate roles of shear and dilational surface viscosity are also elucidated, extending results from small deformation analysis. Indeed, shear (dilational) surface viscosity increases (decreases) the stability of drops to breakup under shear flow. The steady-state deformation (Taylor parameter) varies nonlinearly with each Boussinesq number or a linear combination of both Boussinesq numbers. Finally, the study shows that for certain combinations of shear and dilational viscosities, drop deformation for a given capillary number is the same as in the case of a clean surface while the inclination angle varies.
J. Gounley, G. Boedec, Marc Jaeger, M. Leonetti. Influence of surface viscosity on droplets in shear flow. Journal of Fluid Mechanics, 2016, 791, pp.464- 494. ⟨10.1017/jfm.2016.39⟩. ⟨hal-01281643⟩
J. Gounley, G. Boedec, Marc Jaeger, M. Leonetti. Influence of surface viscosity on droplets in shear flow. Journal of Fluid Mechanics, 2016, 791, pp.464- 494. ⟨10.1017/jfm.2016.39⟩. ⟨hal-01281643⟩ Plus de détails...
The behaviour of a single droplet in an immiscible external fluid, submitted to shear flow is investigated using numerical simulations. The surface of the droplet is modelled by a Boussinesq–Scriven constitutive law involving the interfacial viscosities and a constant surface tension. A numerical method using Loop subdivision surfaces to represent droplet interface is introduced. This method couples boundary element method for fluid flows and finite element method to take into account the stresses due to the surface dilational and shear viscosities and surface tension. Validation of the numerical scheme with respect to previous analytic and computational work is provided, with particular attention to the viscosity contrast and the shear and dilational viscosities characterized both by a Boussinesq number Bq. Then, influence of equal surface viscosities on steady-state characteristics of a droplet in shear flow are studied, considering both small and large deformations and for a large range of bulk viscosity contrast. We find that small deformation analysis is surprisingly predictive at moderate and high surface viscosities. Equal surface viscosities decrease the Taylor deformation parameter and tank-treading angle and also strongly modify the dynamics of the droplet: when the Boussinesq number (surface viscosity) is large relative to the capillary number (surface tension), the droplet displays damped oscillations prior to steady-state tank-treading, reminiscent from the behaviour at large viscosity contrast. In the limit of infinite capillary number Ca, such oscillations are permanent. The influence of surface viscosities on breakup is also investigated, and results show that the critical capillary number is increased. A diagram (Bq;Ca) of breakup is established with the same inner and outer bulk viscosities. Additionally, the separate roles of shear and dilational surface viscosity are also elucidated, extending results from small deformation analysis. Indeed, shear (dilational) surface viscosity increases (decreases) the stability of drops to breakup under shear flow. The steady-state deformation (Taylor parameter) varies nonlinearly with each Boussinesq number or a linear combination of both Boussinesq numbers. Finally, the study shows that for certain combinations of shear and dilational viscosities, drop deformation for a given capillary number is the same as in the case of a clean surface while the inclination angle varies.
J. Gounley, G. Boedec, Marc Jaeger, M. Leonetti. Influence of surface viscosity on droplets in shear flow. Journal of Fluid Mechanics, 2016, 791, pp.464- 494. ⟨10.1017/jfm.2016.39⟩. ⟨hal-01281643⟩
Achim Guckenberger, Marcel P. Schrame, Paul G. Chen, Marc Leonetti, Stephan Gekle. On the bending algorithms for soft objects in flows. Computer Physics Communications, 2016, 207, pp.1-23. ⟨10.1016/j.cpc.2016.04.018⟩. ⟨hal-01314722⟩ Plus de détails...
One of the most challenging aspects in the accurate simulation of three-dimensional soft objects such as vesicles or biological cells is the computation of membrane bending forces. The origin of this difficulty stems from the need to numerically evaluate a fourth order derivative on the discretized surface geometry. Here we investigate six different algorithms to compute membrane bending forces, including regularly used methods as well as novel ones. All are based on the same physical model (due to Canham and Helfrich) and start from a surface discretization with flat triangles. At the same time, they differ substantially in their numerical approach. We start by comparing the numerically obtained mean curvature, the Laplace-Beltrami operator of the mean curvature and finally the surface force density to analytical results for the discocyte resting shape of a red blood cell. We find that none of the considered algorithms converges to zero error at all nodes and that for some algorithms the error even diverges. There is furthermore a pronounced influence of the mesh structure: Discretizations with more irregular triangles and node connectivity present serious difficulties for most investigated methods. To assess the behavior of the algorithms in a realistic physical application, we investigate the deformation of an initially spherical capsule in a linear shear flow at small Reynolds numbers. To exclude any influence of the flow solver, two conceptually very different solvers are employed: the Lattice-Boltzmann and the Boundary Integral Method. Despite the largely different quality of the bending algorithms when applied to the static red blood cell, we find that in the actual flow situation most algorithms give consistent results for both hydrodynamic solvers. Even so, a short review of earlier works reveals a wide scattering of reported results for, e.g., the Taylor deformation parameter. Besides the presented application to biofluidic systems, the investigated algorithms are also of high relevance to the computer graphics and numerical mathematics communities.
Achim Guckenberger, Marcel P. Schrame, Paul G. Chen, Marc Leonetti, Stephan Gekle. On the bending algorithms for soft objects in flows. Computer Physics Communications, 2016, 207, pp.1-23. ⟨10.1016/j.cpc.2016.04.018⟩. ⟨hal-01314722⟩
Achim Guckenberger, Marcel P. Schrame, Paul G. Chen, Marc Leonetti, Stephan Gekle. On the bending algorithms for soft objects in flows. Computer Physics Communications, 2016, 207, pp.1-23. ⟨10.1016/j.cpc.2016.04.018⟩. ⟨hal-01314722⟩ Plus de détails...
One of the most challenging aspects in the accurate simulation of three-dimensional soft objects such as vesicles or biological cells is the computation of membrane bending forces. The origin of this difficulty stems from the need to numerically evaluate a fourth order derivative on the discretized surface geometry. Here we investigate six different algorithms to compute membrane bending forces, including regularly used methods as well as novel ones. All are based on the same physical model (due to Canham and Helfrich) and start from a surface discretization with flat triangles. At the same time, they differ substantially in their numerical approach. We start by comparing the numerically obtained mean curvature, the Laplace-Beltrami operator of the mean curvature and finally the surface force density to analytical results for the discocyte resting shape of a red blood cell. We find that none of the considered algorithms converges to zero error at all nodes and that for some algorithms the error even diverges. There is furthermore a pronounced influence of the mesh structure: Discretizations with more irregular triangles and node connectivity present serious difficulties for most investigated methods. To assess the behavior of the algorithms in a realistic physical application, we investigate the deformation of an initially spherical capsule in a linear shear flow at small Reynolds numbers. To exclude any influence of the flow solver, two conceptually very different solvers are employed: the Lattice-Boltzmann and the Boundary Integral Method. Despite the largely different quality of the bending algorithms when applied to the static red blood cell, we find that in the actual flow situation most algorithms give consistent results for both hydrodynamic solvers. Even so, a short review of earlier works reveals a wide scattering of reported results for, e.g., the Taylor deformation parameter. Besides the presented application to biofluidic systems, the investigated algorithms are also of high relevance to the computer graphics and numerical mathematics communities.
Achim Guckenberger, Marcel P. Schrame, Paul G. Chen, Marc Leonetti, Stephan Gekle. On the bending algorithms for soft objects in flows. Computer Physics Communications, 2016, 207, pp.1-23. ⟨10.1016/j.cpc.2016.04.018⟩. ⟨hal-01314722⟩
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Influence of Rough and Smooth Walls on Macroscale Granular Segregation Patterns. Physical Review E , 2016, 93 (2), pp.022906. ⟨10.1103/PhysRevE.93.022906⟩. ⟨hal-01306600⟩ Plus de détails...
Size bidisperse granular materials in a spherical tumbler segregate into two different patterns of three bands with either small particles at the equator and large particles at the poles or vice versa, depending upon the fill level in the tumbler. Here we use discrete element method (DEM) simulations with supporting qualitative experiments to explore the effect of the tumbler wall roughness on the segregation pattern, modeling the tumbler walls as either a closely packed monolayer of fixed particles resulting in a rough wall, or as a geometrically smooth wall. Even though the tumbler wall is in contact with the flowing layer only at its periphery, the impact of wall roughness is profound. Smooth walls tend toward a small-large-small (SLS) band pattern at the pole-equator-pole at all but the highest fill fractions; rough walls tend toward a large-small-large (LSL) band pattern at all but the lowest fill fractions. This comes about because smooth walls induce poleward axial drift of small particles and an equator-directed drift for large particles, resulting in an SLS band pattern. On the other hand, rough walls result in both sizes of particles moving poleward at the surface of the flow, but due to radial segregation, small particles percolate lower in the flowing layer where there is a return drift toward the equator while large particles remain at the surface near the pole, resulting in an LSL band pattern. The tendency toward either of the two band patterns depends on the fill level in the tumbler and the roughness of the tumbler's bounding wall.
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Influence of Rough and Smooth Walls on Macroscale Granular Segregation Patterns. Physical Review E , 2016, 93 (2), pp.022906. ⟨10.1103/PhysRevE.93.022906⟩. ⟨hal-01306600⟩
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩ Plus de détails...
The problem of a vesicle transported by a fluid flow can present a large range of length scales. One example is the case of a vesicle producing a tether, and eventually pearls, in an elongational flow. Another case occurs when a lubrication film is formed, such as during the short range interaction between two vesicles. Such problems are still challenging for 3D simulations. On the other hand, a good understanding could be obtained by first considering the axisymmetric regime when such a regime exists. An axisymmetric model could then be used, without the criticisms that can be made of a 2D approach. We propose such a model, primarily interested in flows through narrow cylindrical capillaries. Two options are compared, with and without explicit representation of the capillary boundaries by a mesh. The numerical effort is characterized as a function of the vesicle’s initial shape, the flow magnitude and the confinement. The model is able to treat typical configurations of red blood cells flowing through very narrow pores with extremely thin lubrication films.
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩ Plus de détails...
The problem of a vesicle transported by a fluid flow can present a large range of length scales. One example is the case of a vesicle producing a tether, and eventually pearls, in an elongational flow. Another case occurs when a lubrication film is formed, such as during the short range interaction between two vesicles. Such problems are still challenging for 3D simulations. On the other hand, a good understanding could be obtained by first considering the axisymmetric regime when such a regime exists. An axisymmetric model could then be used, without the criticisms that can be made of a 2D approach. We propose such a model, primarily interested in flows through narrow cylindrical capillaries. Two options are compared, with and without explicit representation of the capillary boundaries by a mesh. The numerical effort is characterized as a function of the vesicle’s initial shape, the flow magnitude and the confinement. The model is able to treat typical configurations of red blood cells flowing through very narrow pores with extremely thin lubrication films.
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩
Gustavo Henndel . Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight-Nanofiltration Processes. Chemical Engineering and Technology, 2015, 38 (4), pp.585-594. ⟨10.1002/ceat.201400654⟩. ⟨hal-01135689⟩ Plus de détails...
The performance of reverse osmosis and tight nanofiltration with flat-sheet membranes can be predicted accurately. The proposed numerical model solves the local momentum and mass conservation equations in the module's feed channel with solution-diffusion boundary conditions. Both qualitative and quantitative predictions of the permeate flux and of the rejection rate are obtained with an accuracy depending on the limitations of the solution-diffusion model for describing membrane mass transport and on the value of solute permeability. As an extension of the applications to plate-and-frame modules, the ability to describe the performance of processes carried out with spiral-wound modules is also tested with own desalination experiments and with data from the literature.
Gustavo Henndel . Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight-Nanofiltration Processes. Chemical Engineering and Technology, 2015, 38 (4), pp.585-594. ⟨10.1002/ceat.201400654⟩. ⟨hal-01135689⟩
Umberto d'Ortona, Nathalie Thomas, Zafir Zaman, Richard M. Lueptow. Influence of rough and smooth walls on macroscale flows in tumblers. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2015, 92 (6), pp.062202. ⟨10.1103/PhysRevE.92.062202⟩. ⟨hal-01306604⟩ Plus de détails...
Walls in discrete element method simulations of granular flows are sometimes modeled as a closely packed monolayer of fixed particles, resulting in a rough wall rather than a geometrically smooth wall. An implicit assumption is that the resulting rough wall differs from a smooth wall only locally at the particle scale. Here we test this assumption by considering the impact of the wall roughness at the periphery of the flowing layer on the flow of monodisperse particles in a rotating spherical tumbler. We find that varying the wall roughness significantly alters average particle trajectories even far from the wall. Rough walls induce greater poleward axial drift of particles near the flowing layer surface but decrease the curvature of the trajectories. Increasing the volume fill level in the tumbler has little effect on the axial drift for rough walls but increases the drift while reducing curvature of the particle trajectories for smooth walls. The mechanism for these effects is related to the degree of local slip at the bounding wall, which alters the flowing layer thickness near the walls, affecting the particle trajectories even far from the walls near the equator of the tumbler. Thus, the proper choice of wall conditions is important in the accurate simulation of granular flows, even far from the bounding wall.
Umberto d'Ortona, Nathalie Thomas, Zafir Zaman, Richard M. Lueptow. Influence of rough and smooth walls on macroscale flows in tumblers. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2015, 92 (6), pp.062202. ⟨10.1103/PhysRevE.92.062202⟩. ⟨hal-01306604⟩
Journal: Physical Review E : Statistical, Nonlinear, and Soft Matter Physics
Gustavo Henndel . Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse
. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩ Plus de détails...
Le procédé d’osmose inverse s’impose aujourd'hui dans la production d’eau douce par dessalement. Des avancées en matière de prédiction des performances de ce procédé s’avèrent précieuses dans l’optimisation rapide et peu coûteuse des conditions de fonctionnement. L’interaction entre les propriétés de la membrane et les phénomènes prépondérants (polarisation de concentration, pression osmotique...) constitue un problème scientifiquement complexe, traité dans cette étude via une approche modélisation numérique-simulation-expérimentation, une question centrale pour le génie des procédés.
Gustavo Henndel . Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse
. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩
M. Jaeger, G. Deiana, S. Nash, J.-Y. Bar, F. Cotton, et al.. Prognostic factors of long-term outcome in cases of severe traumatic brain injury. Annals of Physical and Rehabilitation Medicine, 2014, 57 (6-7), pp.436-451. ⟨10.1016/j.rehab.2014.06.001⟩. ⟨hal-02083254⟩ Plus de détails...
M. Jaeger, G. Deiana, S. Nash, J.-Y. Bar, F. Cotton, et al.. Prognostic factors of long-term outcome in cases of severe traumatic brain injury. Annals of Physical and Rehabilitation Medicine, 2014, 57 (6-7), pp.436-451. ⟨10.1016/j.rehab.2014.06.001⟩. ⟨hal-02083254⟩
Journal: Annals of Physical and Rehabilitation Medicine
G. Boedec, Marc Jaeger, Marc Leonetti. Pearling instability of a cylindrical vesicle. Journal of Fluid Mechanics, 2014, 743, pp.262-279. ⟨10.1017/jfm.2014.34⟩. ⟨hal-01050140⟩ Plus de détails...
A cylindrical vesicle under tension can undergo a pearling instability, characterized by the growth of a sinusoidal perturbation which evolves towards a collection of quasi-spherical bulbs connected by thin tethers, like pearls on a necklace. This is reminiscent of the well-known Rayleigh-Plateau instability, where surface tension drives the amplification of sinusoidal perturbations of a cylinder of fluid. We calculate the growth rate of perturbations for a cylindrical vesicle under tension, considering the effect of both inner and outer fluids, with different viscosities. We show that this situation differs strongly from the classical Rayleigh-Plateau case in the sense that, first, the tension must be above a critical value for the instability to develop and, second, even in the strong tension limit, the surface preservation constraint imposed by the presence of the membrane leads to a different asymptotic behaviour. The results differ from previous studies on pearling due to the consideration of variations of tension, which are shown to enhance the pearling instability growth rate, and lower the wavenumber of the fastest growing mode.
G. Boedec, Marc Jaeger, Marc Leonetti. Pearling instability of a cylindrical vesicle. Journal of Fluid Mechanics, 2014, 743, pp.262-279. ⟨10.1017/jfm.2014.34⟩. ⟨hal-01050140⟩
Henri Gouin. Interfaces endowed with nonconstant surface energies revisited with the d'Alembert–Lagrange principle. Mathematics and Mechanics of Complex Systems, 2014, 2 (1), pp.23-43. ⟨hal-01152429⟩ Plus de détails...
The equation of motion and the conditions on surfaces and edges between fluids and solids in the presence of nonconstant surface energies, as in the case of surfactants attached to fluid particles at the interfaces, are revisited under the principle of virtual work. We point out that adequate behaviors of surface concentrations may drastically modify the surface tension which naturally appears in the Laplace and the Young–Dupré equations. Thus, the principle of virtual work points out a strong difference between the two revisited concepts of surface energy and surface tension.
Henri Gouin. Interfaces endowed with nonconstant surface energies revisited with the d'Alembert–Lagrange principle. Mathematics and Mechanics of Complex Systems, 2014, 2 (1), pp.23-43. ⟨hal-01152429⟩
Journal: Mathematics and Mechanics of Complex Systems
Zafir Zaman, Umberto d'Ortona, Paul B. Umbanhowar, Julio M. Ottino, Richard M. Lueptow. Slow axial drift in three-dimensional granular tumbler flow. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, 88 (1), pp.012208. ⟨10.1103/PhysRevE.88.012208⟩. ⟨hal-00905562⟩ Plus de détails...
Models of monodisperse particle flow in partially filled three-dimensional tumblers often assume that flow along the axis of rotation is negligible. We test this assumption, for spherical and double cone tumblers, using experiments and discrete element method simulations. Cross sections through the particle bed of a spherical tumbler show that, after a few rotations, a colored band of particles initially perpendicular to the axis of rotation deforms: particles near the surface drift toward the pole, while particles deeper in the flowing layer drift toward the equator. Tracking of mm-sized surface particles in tumblers with diameters of 8-14 cm shows particle axial displacements of one to two particle diameters, corresponding to axial drift that is 1-3% of the tumbler diameter, per pass through the flowing layer. The surface axial drift in both double cone and spherical tumblers is zero at the equator, increases moving away from the equator, and then decreases near the poles. Comparing results for the two tumbler geometries shows that wall slope causes axial drift, while drift speed increases with equatorial diameter. The dependence of axial drift on axial position for each tumbler geometry is similar when both are normalized by their respective maximum values.
Zafir Zaman, Umberto d'Ortona, Paul B. Umbanhowar, Julio M. Ottino, Richard M. Lueptow. Slow axial drift in three-dimensional granular tumbler flow. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, 88 (1), pp.012208. ⟨10.1103/PhysRevE.88.012208⟩. ⟨hal-00905562⟩
Journal: Physical Review E : Statistical, Nonlinear, and Soft Matter Physics
T. Prusek, E. Moleiro, F. Oukacine, A. Adobes, Marc Jaeger, et al.. Deposit models for tube support plate flow blockage in Steam Generators. Nuclear Engineering and Design, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩ Plus de détails...
Corrosion product deposits in the secondary side of nuclear power plant Steam Generators may result in Tube Support Plate flow blockage, and tube fouling. In order to simulate those two phenomena in the whole Steam Generator, a solid deposit growth model has been developed by the EDF R&D Division. This model is implemented in the frame of THYC, which is the EDF's reference code for the modeling of two-phase thermal-hydraulic phenomena at the subchannel scale. A new deposit process, based on Tube Support Plate flow blockage studies, has been developed and implemented in the model, and is presented in this work. It can be defined by two main steps: particle deposition, and strengthening process called "flashing" due to soluble species precipitation in the pores of the particle deposit. The relevance of this process is tested by comparing the simulation results to the actual levels of flow blockage observed in some nuclear plants. Two dominant trends are showed in this work: the flow blockage is more important on the hot leg than on the cold leg and at the top than at the bottom of the Steam Generators. Moreover the flow blockages at the upper Tube Support Plate have the special feature to be more important at the periphery than at the center. The "flashing" phenomenon allows one to underline the magnetite solubility dependence, so the pH dependence, of flow blockage phenomenon. A pH elevation of the secondary circuit seems to be a interesting remedy which is currently considered on EDF fleet.
T. Prusek, E. Moleiro, F. Oukacine, A. Adobes, Marc Jaeger, et al.. Deposit models for tube support plate flow blockage in Steam Generators. Nuclear Engineering and Design, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩
Marc Leonetti, Gwenn Boedec, Marc Jaeger. Breathing instability in biological cells, patterns of membrane proteins. Discontinuity, Nonlinearity, and Complexity, 2013, 2 (1), pp.75-84. ⟨10.5890/DNC.2012.12.001⟩. ⟨hal-00997680⟩ Plus de détails...
The activity of biological cells involves often the electric activity of its membranes which exhibit various spatiotemporal dynamics, from pulse, oscillatory bifurcation to stationary spatial modulation. This last kind of patterns appears on a typical diffusive time. A model has been proposed implying a coupling between the current flowing through membrane proteins and their electrophoretic motions in the case of mobile proteins. Here, we study the stability of the pattern in a 2D circular model cell versus the appearance of standing waves, the so-called breathing secondary instability.
Marc Leonetti, Gwenn Boedec, Marc Jaeger. Breathing instability in biological cells, patterns of membrane proteins. Discontinuity, Nonlinearity, and Complexity, 2013, 2 (1), pp.75-84. ⟨10.5890/DNC.2012.12.001⟩. ⟨hal-00997680⟩
Journal: Discontinuity, Nonlinearity, and Complexity
H. Hchaichi, Hamza Elfil, Pierrette Guichardon, Ahmed Hannachi. Scaling tendency assessment in reverse osmosis modules. Desalination and Water Treatment, 2013, 51 (4-6), pp.892-898. ⟨10.1080/19443994.2012.715410⟩. ⟨hal-01464722⟩ Plus de détails...
A mathematical model was developed to predict super saturation along ă reverse osmosis modules (RO) for water desalination. This model is based on conservation principles and chemical equilibrium equations for concentrated solutions. Pitzer's model was used for the activity coefficient calculations. An average rejection rate for each ionic species was also considered. Supersaturations with respect to all calcium carbonate forms and to calcium sulfate are calculated. The model allows assessing when scale is likely to occur along the RO modules. The results for two brackish water qualities and seawater are shown.
H. Hchaichi, Hamza Elfil, Pierrette Guichardon, Ahmed Hannachi. Scaling tendency assessment in reverse osmosis modules. Desalination and Water Treatment, 2013, 51 (4-6), pp.892-898. ⟨10.1080/19443994.2012.715410⟩. ⟨hal-01464722⟩
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Sedimentation-induced tether on a settling vesicle. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, 88, pp.010702. ⟨10.1103/PhysRevE.88.010702⟩. ⟨hal-00997686⟩ Plus de détails...
Destabilization of soft interfaces into thin cylindrical filaments under external stresses is ubiquitous and is generally the first step toward breakup. We show that such filaments, called tethers, emerge from a vesicle subjected to gravity. Contrary to the pendant drop experiment, we demonstrate that the bending rigidity, a specific membrane property of vesicles, ensures the tethers reach a stationary state. Moreover, unlike point-like force experiments, we show that the family of shapes is continuous.
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Sedimentation-induced tether on a settling vesicle. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, 88, pp.010702. ⟨10.1103/PhysRevE.88.010702⟩. ⟨hal-00997686⟩
Journal: Physical Review E : Statistical, Nonlinear, and Soft Matter Physics
Elena Alekseenko, Bernard Roux, Anton Sukhinov, Richard Kotarba, Dominique Fougere. Nonlinear hydrodynamics in a Mediterranean lagoon. Nonlinear Processes in Geophysics, 2013, 20 (2), pp.189-198. ⟨10.5194/npg-20-189-2013⟩. ⟨hal-01464721⟩ Plus de détails...
The paper addresses the application of the nonlinear hydrodynamics model (RANS (Reynolds-averaged Navier-Stokes) equations) in a wide semi-enclosed Mediterranean lagoon (Berre lagoon), considering three ă natural forcing functions, i.e., sea tide propagating through a long narrow channel, wind and runoff. Main attention is focused to characteristic velocities (at free surface and bottom) and to free surface elevation associated to each of these three mechanisms, with special attention to the nearshore areas (i.e., in shallow water). The most interesting result concerns wind effects which, due to Berre lagoon bathymetry, give rise to downwind coastal jets, alongshore, in shallow water areas. Such coastal jets were never mentioned before in Berre lagoon literature.
Elena Alekseenko, Bernard Roux, Anton Sukhinov, Richard Kotarba, Dominique Fougere. Nonlinear hydrodynamics in a Mediterranean lagoon. Nonlinear Processes in Geophysics, 2013, 20 (2), pp.189-198. ⟨10.5194/npg-20-189-2013⟩. ⟨hal-01464721⟩
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Supercritical water oxidation of ion exchange resins in a stirred reactor: numerical modelling. Chemical Engineering Science, 2012, 69 (1), pp.170-180. ⟨10.1016/j.ces.2011.10.016⟩. ⟨hal-00993023⟩ Plus de détails...
Supercritical water oxidation offers a viable alternative treatment to destroy the organic structure of Ion Exchange Resins. In order to design and define appropriate dimensions for the supercritical oxidation reactor, a 2D simulation of the fluid dynamics and heat transfer during the oxidation process has been investigated. The solver used is a commercial code, Fluent® 6.3. The turbulent flow field in the reactor, created by the stirrer is taken into account with a k−ω model and a swirl imposed to the fluid. Particle trajectories are modelled with the Discrete Random Walk Particle Model. For the solubilization of the particles in supercritical water, a mechanism has been proposed and implemented into Fluent® software through the Eddy Dissipation Concept approach, taking into account the identified rate determining species. Simulation results provide results on the flow, temperature fields and oxidation localization inside the reactor. For the reactive particles-supercritical water flow model, the effect of parameters, such as feed flow rates or stirring velocity, can be focussed. Reaction temperature is predicted with deviation lower than 15%. Degradation conversions are in good agreement with experimental ones.
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Supercritical water oxidation of ion exchange resins in a stirred reactor: numerical modelling. Chemical Engineering Science, 2012, 69 (1), pp.170-180. ⟨10.1016/j.ces.2011.10.016⟩. ⟨hal-00993023⟩
G.H. Lopes, B. Bernales Chavez, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Prediction of Permeate Flux and Rejection Rate in RO and NF Membrane Processes: Numerical Modelling of Hydrodynamics and Mass Transfer Coupling. Procedia Engineering, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩ Plus de détails...
G.H. Lopes, B. Bernales Chavez, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Prediction of Permeate Flux and Rejection Rate in RO and NF Membrane Processes: Numerical Modelling of Hydrodynamics and Mass Transfer Coupling. Procedia Engineering, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩
S. Moussiere, A. Roubaud, Olivier Boutin, Pierrette Guichardon, B. Fournel, et al.. 2D and 3D CFD modelling of a reactive turbulent flow in a double shell supercritical water oxidation reactor. Journal of Supercritical Fluids, 2012, 65, pp.25-31. ⟨10.1016/j.supflu.2012.02.019⟩. ⟨hal-00992976⟩ Plus de détails...
In order to design and define appropriate dimensions for a supercritical oxidation reactor, a comparative 2D and 3D simulation of the fluid dynamics and heat transfer during an oxidation process has been performed. The solver used is a commercial code, Fluent 6.2®. The turbulent flow field in the reactor, created by the stirrer, is taken into account with a k-ω model and a swirl imposed to the fluid. In the 3D case the rotation of the stirrer can be modelled using the sliding mesh model and the moving reference frame model. This work allows comparing 2D and 3D velocity and heat transfer calculations. The predicted values (mainly species concentrations and temperature profiles) are of the same order in both cases. The reactivity of the system is taken into account with a classical Eddy Dissipation Concept combustion model. Comparisons with experimental temperature measurements validate the ability of the CFD modelling to simulate the supercritical water oxidation reactive medium. Results indicate that the flow can be considered as plug flow-like and that heat transfer is strongly enhanced by the stirring.
S. Moussiere, A. Roubaud, Olivier Boutin, Pierrette Guichardon, B. Fournel, et al.. 2D and 3D CFD modelling of a reactive turbulent flow in a double shell supercritical water oxidation reactor. Journal of Supercritical Fluids, 2012, 65, pp.25-31. ⟨10.1016/j.supflu.2012.02.019⟩. ⟨hal-00992976⟩
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Settling of a vesicle in the limit of quasi-spherical shapes. Journal of Fluid Mechanics, 2012, 690, pp.227-261. ⟨10.1017/jfm.2011.427⟩. ⟨hal-00997678⟩ Plus de détails...
Vesicles are drops of radius of a few tens of micrometres bounded by an impermeable lipid membrane of approximately 4 nm thickness in a viscous fluid. The salient characteristics of such a deformable object are a membrane rigidity governed by flexion due to curvature energy and a two-dimensional membrane fluidity characterized by a local membrane incompressibility. This provides unique properties with strong constraints on the internal volume and membrane area. Yet, when subjected to external stresses, vesicles exhibit a large deformability. The deformation of a settling vesicle in an infinite flow is studied theoretically, assuming a quasispherical shape and expanding all variables of the problem onto spherical harmonics. The contribution of thermal fluctuations is neglected in this analysis. A system of equations describing the temporal evolution of the shape is derived with this formalism. The final shape and the settling velocity are then determined and depend on two dimensionless parameters: the Bond number and the excess area. This simultaneous study leads to three stationary shapes, an egg-like shape already observed in an analogous experimental configuration in the limit of weak flow magnitude (Chatkaew, Georgelin, Jaeger & Leonetti, Phys. Rev. Lett, 2009, vol. 103(24), 248103), a parachute-like shape and a non-trivial non-axisymmetrical shape. The final shape depends on the initial conditions: prolate or oblate vesicle and orientation compared with gravity. The analytical solution in the small deformation regime is compared with numerical results obtained with a three-dimensional code. A very good agreement between numerical and theoretical results is found.
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Settling of a vesicle in the limit of quasi-spherical shapes. Journal of Fluid Mechanics, 2012, 690, pp.227-261. ⟨10.1017/jfm.2011.427⟩. ⟨hal-00997678⟩
Pierre Haldenwang, Pierrette Guichardon. Pressure runaway in a 2D plane channel with permeable walls submitted to pressure-dependent suction. European Journal of Mechanics - B/Fluids, 2011, 30 (2), pp.177-183. ⟨10.1016/j.euromechflu.2010.09.007⟩. ⟨hal-00905831⟩ Plus de détails...
A leaking duct carries a flow that is a characteristic of several applications. Devices for cross-flow microfiltration are composed of a duct, the walls of which are semi-permeable membranes. In subsurface irrigation, the walls of watering pipes can be of porous clay, whereas the watering hoses are riddled with holes or made of porous material, in surface drip irrigation. In these applications, the first approach consists of assuming that the flow concerns a pure fluid (as in a microfiltration system operating at a very low species concentration), and that the wall's leakage depends only on the local pressure difference between both inner and outer sides of the wall.
Pierre Haldenwang, Pierrette Guichardon. Pressure runaway in a 2D plane channel with permeable walls submitted to pressure-dependent suction. European Journal of Mechanics - B/Fluids, 2011, 30 (2), pp.177-183. ⟨10.1016/j.euromechflu.2010.09.007⟩. ⟨hal-00905831⟩
Pierre Haldenwang, Pierrette Guichardon, Guillaume Chiavassa, N. Ibaseta. Exact solution to mass transfer in Berman flow: application to concentration polarization combined with osmosis in crossflow membrane filtration. International Journal of Heat and Mass Transfer, 2010, 53 (19-20), pp.3898-3904. ⟨10.1016/j.ijheatmasstransfer.2010.05.008⟩. ⟨hal-00907275⟩ Plus de détails...
Concentration polarization affects numerous systems of membrane separation, and combined with osmosis, it can cause substantial reductions in permeation. We establish an exact solution to the conservation law of a solute advected by Berman flow. This flow is characteristic of reverse osmosis or nanofiltration. The resulting concentration polarization is then combined with the osmosis (counter-) effect. For large Péclet number of permeation, it yields a rigorous support to the semi-empirical "film" model, and accounts for the limit flux phenomenon. The main results are summarized in a simple diagram that relates three different Péclet numbers, and show that polarization combined with osmosis can withstand operating pressure almost totally.
Pierre Haldenwang, Pierrette Guichardon, Guillaume Chiavassa, N. Ibaseta. Exact solution to mass transfer in Berman flow: application to concentration polarization combined with osmosis in crossflow membrane filtration. International Journal of Heat and Mass Transfer, 2010, 53 (19-20), pp.3898-3904. ⟨10.1016/j.ijheatmasstransfer.2010.05.008⟩. ⟨hal-00907275⟩
Journal: International Journal of Heat and Mass Transfer
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Ion exchange resins destruction in a stirred supercritical water oxidation reactor. Journal of Supercritical Fluids, 2010, 51 (3), pp.369-375. ⟨10.1016/j.supflu.2009.08.017⟩. ⟨hal-01025175⟩ Plus de détails...
Spent ion exchange resins (IERs) are radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation offers a viable treatment alternative to destroy the organic structure of resins, used to remove radioactivity. Up to now, studies carried out in supercritical water for IER destruction showed that degradation rates higher than 99% are difficult to obtain even using a catalyst or a large oxidant excess. In this study, a co-fuel, isopropanol, has been used in order to improve degradation rates by initiating the oxidation reaction and increasing temperature of the reaction medium. Concentrations up to 20 wt% were tested for anionic and cationic resins. Total organic carbon reduction rates higher than 99% were obtained from this process, without the use of a catalyst. The influence of operating parameters such as IERs feed concentration, nature and counterions of exchanged IERs were also studied.
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Ion exchange resins destruction in a stirred supercritical water oxidation reactor. Journal of Supercritical Fluids, 2010, 51 (3), pp.369-375. ⟨10.1016/j.supflu.2009.08.017⟩. ⟨hal-01025175⟩
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Supercritical water oxidation of ion exchange resins: degradation mechanisms. Process Safety and Environmental Protection, 2010, 88 (3), pp.213-222. ⟨10.1016/j.psep.2009.11.001⟩. ⟨hal-01025162⟩ Plus de détails...
Spent ion exchange resins are radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation could offer a viable treatment alternative to destroy the organic structure of resins and contain radioactivity. IER degradation experiments were carried out in a continuous supercritical water reactor. Total organic carbon degradation rates in the range of 95-98% were obtained depending on operating conditions. GC-MS chromatography analyses were carried out to determine intermediate products formed during the reaction. Around 50 species were identified for cationic and anionic resins. Degradation of polystyrenic structure leads to the formation of low molecular weight compounds. Benzoic acid, phenol and acetic acid are the main compounds. However, other products are detected in appreciable yields such as phenolic species or heterocycles, for anionic IERs degradation. Intermediates produced by intramolecular rearrangements are also obtained. A radical degradation mechanism is proposed for each resin. In this overall mechanism, several hypotheses are foreseen, according to HOOradical dot radical attack sites.
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Supercritical water oxidation of ion exchange resins: degradation mechanisms. Process Safety and Environmental Protection, 2010, 88 (3), pp.213-222. ⟨10.1016/j.psep.2009.11.001⟩. ⟨hal-01025162⟩
Journal: Process Safety and Environmental Protection
Bo Xun, Kai Li, Paul G. Chen, Wen-Rui Hu. Effect of interfacial heat transfer on the onset of oscillatory convection in liquid bridge. International Journal of Heat and Mass Transfer, 2009, 52 (19-20), pp.4211-4220. ⟨10.1016/j.ijheatmasstransfer.2009.04.008⟩. ⟨hal-01307193⟩ Plus de détails...
In present study, effect of interfacial heat transfer with ambient gas on the onset of oscillatory convection in a liquid bridge of large Prandtl number on the ground is systematically investigated by the method of linear stability analyses. With both the constant and linear ambient air temperature distributions, the numerical results show that the interfacial heat transfer modifies the free-surface temperature distribution directly and then induces a steeper temperature gradient on the middle part of the free surface, which may destabilize the convection. On the other hand, the interfacial heat transfer restrains the temperature disturbances on the free surface, which may stabilize the convection. The two coupling effects result in a complex dependence of the stability property on the Biot number. Effects of melt free-surface deformation on the critical conditions of the oscillatory convection were also investigated. Moreover, to better understand the mechanism of the instabilities, rates of kinetic energy change and ''thermal " energy change of the critical disturbances were investigated
Bo Xun, Kai Li, Paul G. Chen, Wen-Rui Hu. Effect of interfacial heat transfer on the onset of oscillatory convection in liquid bridge. International Journal of Heat and Mass Transfer, 2009, 52 (19-20), pp.4211-4220. ⟨10.1016/j.ijheatmasstransfer.2009.04.008⟩. ⟨hal-01307193⟩
Journal: International Journal of Heat and Mass Transfer
Jian-Kang Zhang, Bo Xun, Paul G. Chen. A Continuation Method Applied to the Study of Thermocapillary Instabilities in Liquid Bridges. Microgravity Science & Technology, 2009, 21 (Suppl 1), pp.111-117. ⟨10.1007/s12217-009-9111-2⟩. ⟨hal-01307220⟩ Plus de détails...
A continuation method is applied to investigate the linear stability of the steady, axisymmetric thermocapillary flows in liquid bridges. The method is based upon an appropriate extended system of perturbation equations depending on the nature of transition of the basic flow. The dependence of the critical Reynolds number and corresponding azimuthal wavenumber on serval parameters is presented for both cylindrical and non-cylindrical liquid bridges.
Jian-Kang Zhang, Bo Xun, Paul G. Chen. A Continuation Method Applied to the Study of Thermocapillary Instabilities in Liquid Bridges. Microgravity Science & Technology, 2009, 21 (Suppl 1), pp.111-117. ⟨10.1007/s12217-009-9111-2⟩. ⟨hal-01307220⟩
B Xun, Paul G. Chen, K Li, Z Yin, W.R. Hu. A linear stability analysis of large-Prandtl-number thermocapillary liquid bridges. Advances in Space Research, 2008, 41 (12), pp.2094-2100. ⟨10.1016/j.asr.2007.07.016⟩. ⟨hal-01307161⟩ Plus de détails...
A linear stability analysis is applied to determine the onset of oscillatory thermocapillary convection in cylindrical liquid bridges of large Prandtl numbers (4 ⩽ Pr ⩽ 50). We focus on the relationships between the critical Reynolds number Re c , the azimuthal wave number m, the aspect ratio C and the Prandtl number Pr. A detailed Re c–Pr stability diagram is given for liquid bridges with various C. In the region of Pr > 1, which has been less studied previously and where Re c has been usually believed to decrease with the increase of Pr, we found Re c exhibits an early increase for liquid bridges with C around one. From the computed surface temperature gradient, it is concluded that the boundary layers developed at both solid ends of liquid bridges strengthen the stability of basic axisymmetric thermocap-illary convection at large Prandtl number, and that the stability property of the basic flow is determined by the ''effective'' part of liquid bridge.
B Xun, Paul G. Chen, K Li, Z Yin, W.R. Hu. A linear stability analysis of large-Prandtl-number thermocapillary liquid bridges. Advances in Space Research, 2008, 41 (12), pp.2094-2100. ⟨10.1016/j.asr.2007.07.016⟩. ⟨hal-01307161⟩
S. Moussiere, C. Joussot-Dubien, P. Guichardon, Olivier Boutin, H.-A. Turc, et al.. Modelling of heat transfer and hydrodynamic with two kinetics approaches during supercritical water oxidation process. Journal of Supercritical Fluids, 2007, 43 (2), pp.324-332. ⟨10.1016/j.supflu.2007.06.008⟩. ⟨cea-02512107⟩ Plus de détails...
Supercritical water oxidation is an innovative and very efficient process to treat hazardous organic waste. In order to better understand the complex physic phenomena involved in this process, and to design more efficient reactors or to insure future efficient scale-up, a simulation with the Computational Fluid Dynamics software FLUENT was carried out for a simple tubular reactor. The turbulent non-reactive flow is well-represented using the $\kappa-\epsilon$ model. Nevertheless, the $\kappa-\epsilon$ model gives better results when a source term is added to take into account the chemical reaction. Two approaches are used to model the reaction rate: an Arrhenius law and the Eddy Dissipation Concept (EDC) generally used to describe combustion reactions. The results of this simulation using Arrhenius law, are in good agreement with experimental data although a simple thermohydraulic model was used. Moreover, the sensitiveness to the inlet temperature has been demonstrated. It influences the reaction start-up and the shape of the measured wall temperature peak. Equally, the simulated temperature profiles using Eddy Dissipation Concept model are in good agreement with experimental ones. Hence, the two approaches give similar results. Nevertheless, the EDC model predicts more precisely the thermal peak location at the reactor wall.
S. Moussiere, C. Joussot-Dubien, P. Guichardon, Olivier Boutin, H.-A. Turc, et al.. Modelling of heat transfer and hydrodynamic with two kinetics approaches during supercritical water oxidation process. Journal of Supercritical Fluids, 2007, 43 (2), pp.324-332. ⟨10.1016/j.supflu.2007.06.008⟩. ⟨cea-02512107⟩
M. Jaeger, M. Carin. The Front-Tracking ALE Method: Application to a Model of the Freezing of Cell Suspensions. Journal of Computational Physics, 2002, 179 (2), ⟨10.1006/jcph.2002.7084⟩. ⟨hal-01282007⟩ Plus de détails...
A new front-tracking method to compute discontinuous solutions on unstructured finite element meshes is presented. Using an arbitrary Lagrangian–Eulerian formula- tion, the mesh is continuously adapted by moving the nearest nodes to the interface. Thus, the solution is completely sharp at the interface and no smearing takes place. The dynamic node adjustment is confined to global nodes near the front, rendering remeshing unnecessary. The method has been applied to the osmotic motion of a two-dimensional cell arising from a concentration gradient generated by a moving solidification front. The engulfment of one cell by an advancing solidification front, which rejects the solutes in a binary salt solution, is then computed. The results indicate that the ice increases the solute gradient around the cell. Furthermore, the presence of the cell, which prevents diffusion of the solute, leads to large changes in the morphology of the ice front.
M. Jaeger, M. Carin. The Front-Tracking ALE Method: Application to a Model of the Freezing of Cell Suspensions. Journal of Computational Physics, 2002, 179 (2), ⟨10.1006/jcph.2002.7084⟩. ⟨hal-01282007⟩
M. Carin, M. Jaeger. Numerical simulation of the interaction of biological cells with an ice front during freezing. European Physical Journal: Applied Physics, 2001, 16 (3), ⟨10.1051/epjap:2001205⟩. ⟨hal-01282025⟩ Plus de détails...
The goal of this study is a better understanding of the interaction between cells and a solidi- fication front during a cryopreservation process. This technique of freezing is commonly used to conserve biological material for long periods at low temperatures. However the biophysical mechanisms of cell in- juries during freezing are difficult to understand because a cell is a very sophisticated microstructure interacting with its environment. We have developed a finite element model to simulate the response of cells to an advancing solidification front. A special front-tracking technique is used to compute the motion of the cell membrane and the ice front during freezing. The model solves the conductive heat transfer equation and the diffusion equation of a solute on a domain containing three phases: one or more cells, the extra-cellular solution and the growing ice. This solid phase growing from a binary salt solution rejects the solute in the liquid phase and increases the solute gradient around the cell. This induces the shrinkage of the cell. The model is used to simulate the engulfment of one cell modelling a red blood cell by an advancing solidification front initially planar or not is computed. We compare the incorporation of a cell with that of a solid particle.
M. Carin, M. Jaeger. Numerical simulation of the interaction of biological cells with an ice front during freezing. European Physical Journal: Applied Physics, 2001, 16 (3), ⟨10.1051/epjap:2001205⟩. ⟨hal-01282025⟩
Journal: European Physical Journal: Applied Physics
Iain Shepherd, Tim Haste, Naouma Kourti, Francesco Oriolo, Mario Leonardi, et al.. Investigation of core degradation (COBE). Nuclear Engineering and Design, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩ Plus de détails...
The COBE project started in February 1996 and finished at the end of January 1999. The main objective was to improve understanding of core degradation behaviour during severe accidents through the development of computer codes, the carrying out of experiments and the assessment of the computer codes’ ability to reproduce experimental behaviour. A major effort was devoted to quenching behaviour and a substantial achievement of the project was the design and commissioning of a new facility for the simulation of quenching of intact fuel rods. Two tests, carefully scaled to represent realistic reactor conditions, were carried out in this facility and the hydrogen generated during the quenching process was measured using two independent measuring systems. The codes were able to reproduce the results in the first test, where little hydrogen was generated but not the second test, where the extra steam produced during quenching caused an invigorated Zircaloy oxidation and a substantial hydrogen generation. A number of smaller parametric experiments allowed detailed models to be developed for the absorption of hydrogen and the cracking of cladding during quenching. COBE also investigated other areas concerned with late-phase phenomena.
Iain Shepherd, Tim Haste, Naouma Kourti, Francesco Oriolo, Mario Leonardi, et al.. Investigation of core degradation (COBE). Nuclear Engineering and Design, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩