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Publications de l'équipe Procédés et mécanique aux petites échelles
2019
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, MDPI, 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, MDPI, 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, Elsevier, 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, Elsevier, 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, Springer, 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, Springer, 2018, 30, pp.675-682. ⟨10.1007/s12217-018-9645-2⟩. ⟨hal-02112826⟩
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, Springer, 2018, 30, pp.675-682. ⟨10.1007/s12217-018-9645-2⟩. ⟨hal-01847206⟩ 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, Springer, 2018, 30, pp.675-682. ⟨10.1007/s12217-018-9645-2⟩. ⟨hal-01847206⟩
Umberto D'Ortona, Nathalie Thomas, Richard Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , American Physical Society (APS), 2018, 97 (5). 〈hal-02001973〉 Plus de détails...
Umberto D'Ortona, Nathalie Thomas, Richard Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , American Physical Society (APS), 2018, 97 (5). 〈hal-02001973〉
Jinming Lyu, Paul G. Chen, Gwenn Boedec, Marc Leonetti, Marc Jaeger. Hybrid continuum–coarse-grained modeling of erythrocytes. Comptes Rendus Mécanique, Elsevier Masson, 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, Elsevier Masson, 2018, 346, pp.439-448. ⟨10.1016/j.crme.2018.04.015⟩. ⟨hal-01785429⟩
Umberto d'Ortona, Nathalie Thomas, Richard Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , American Physical Society (APS), 2018, 97 (5), pp.052904. ⟨10.1103/PhysRevE.97.052904⟩. ⟨hal-01875642⟩ 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 Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , American Physical Society (APS), 2018, 97 (5), pp.052904. ⟨10.1103/PhysRevE.97.052904⟩. ⟨hal-01875642⟩
Umberto d'Ortona, Nathalie Thomas, Richard Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , American Physical Society (APS), 2018, 97 (5). ⟨hal-02001973⟩ Plus de détails...
Umberto d'Ortona, Nathalie Thomas, Richard Lueptow. Recirculation cells for granular flow in cylindrical rotating tumblers. Physical Review E , American Physical Society (APS), 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, Frontiers, 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, Frontiers, 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, Wiley-VCH Verlag, 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, Wiley-VCH Verlag, 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, Nature Publishing Group, 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, Nature Publishing Group, 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, Royal Society, The, 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, Royal Society, The, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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. European Physical Journal - Special Topics, EDP Sciences, 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. European Physical Journal - Special Topics, EDP Sciences, 2017, 226 (6), pp.1325-1335. ⟨10.1140/epjst/e2016-60203-y⟩. ⟨hal-01509843⟩
Journal: 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 2017, 187, pp.293-305. ⟨10.1016/j.ecss.2017.01.010⟩. ⟨hal-01453377⟩
M. Dennefeld, W. Brzezinska, M. Nowak, F. Spoto, W. Thuillot, et al.. Comet P/2017 s5 (atlas). Minor Planet Electronic Circulars, International Astronomical Union, 2017. ⟨hal-02268847⟩ Plus de détails...
M. Dennefeld, W. Brzezinska, M. Nowak, F. Spoto, W. Thuillot, et al.. Comet P/2017 s5 (atlas). Minor Planet Electronic Circulars, International Astronomical Union, 2017. ⟨hal-02268847⟩
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, Royal Society of Chemistry, 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, Royal Society of Chemistry, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩
Umberto d'Ortona, Nathalie Thomas, Richard M. Lueptow. Axial segregation in spherical and cylindrical rotating tumblers. EPJ Web of Conferences, EDP Sciences, 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, EDP Sciences, 2017, Powders and Grains 2017 – 8th International Conference on Micromechanics on Granular Media, 140, pp.03011. ⟨10.1051/epjconf/201714003011⟩. ⟨hal-01671207⟩
Kaili Xie, Clément de Loubens, Frédéric Dubreuil, Deniz Z. Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, Royal Society of Chemistry, 2017, 13 (36), pp.6208 - 6217. ⟨10.1039/c7sm01377a⟩. ⟨hal-01631078⟩ Plus de détails...
Tuning the mechanical properties of microcapsules through a 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 into the mechanics of these weakly cohesive membranes. Firstly, suspensions of water-inoil microcapsules were formed in microfluidic junctions by self-assembly 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 and 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 microcapsules can be 'engineered' in an extensive way since they present a wealth of interfacial rheological properties in terms 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, Clément de Loubens, Frédéric Dubreuil, Deniz Z. Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, Royal Society of Chemistry, 2017, 13 (36), pp.6208 - 6217. ⟨10.1039/c7sm01377a⟩. ⟨hal-01631078⟩
Kaili Xie, Clement De Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, Royal Society of Chemistry, 2017, 13 (36), pp.6208-6217. 〈10.1039/C7SM01377A〉. 〈hal-02020103〉 Plus de détails...
Kaili Xie, Clement De Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, Royal Society of Chemistry, 2017, 13 (36), pp.6208-6217. 〈10.1039/C7SM01377A〉. 〈hal-02020103〉
Henri Gouin, Tommaso Ruggeri. Symmetric form for the hyperbolic-parabolic system of fourth-gradient fluid model. Ricerche di matematica, Springer Verlag, 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, Springer Verlag, 2017, 66 (2), pp.491-508. ⟨10.1007/s11587-016-0315-7⟩. ⟨hal-01573721⟩
U. Laux, B. Stecklum, P. Bacci, M. Maestripieri, M. Carotta, et al.. 2017 OH7. Minor Planet Electronic Circulars, International Astronomical Union, 2017. ⟨hal-02268848⟩ Plus de détails...
U. Laux, B. Stecklum, P. Bacci, M. Maestripieri, M. Carotta, et al.. 2017 OH7. Minor Planet Electronic Circulars, International Astronomical Union, 2017. ⟨hal-02268848⟩
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. Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Serie IX. Rendiconti Lincei. Matematica e Applicazioni, European Mathematical Society, 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. Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Serie IX. Rendiconti Lincei. Matematica e Applicazioni, European Mathematical Society, 2017, 28, pp.415-449. ⟨10.4171/RLM/769 ⟩. ⟨hal-01540964⟩
Journal: Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Serie IX. Rendiconti Lincei. Matematica e Applicazioni
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, Elsevier, 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, Elsevier, 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, Cambridge University Press (CUP), 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, Cambridge University Press (CUP), 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, Elsevier, 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, Elsevier, 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 , American Physical Society (APS), 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 , American Physical Society (APS), 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, Elsevier, 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, Elsevier, 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, Wiley-VCH Verlag, 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, Wiley-VCH Verlag, 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, American Physical Society, 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, American Physical Society, 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, Société chimique de France, 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. ⟨http://www.lactualitechimique.org/L-eau-ressource-rare-Gros-plan-sur-le-procede-de⟩. ⟨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, Société chimique de France, 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. ⟨http://www.lactualitechimique.org/L-eau-ressource-rare-Gros-plan-sur-le-procede-de⟩. ⟨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, Elsevier Masson, 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, Elsevier Masson, 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, Cambridge University Press (CUP), 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, Cambridge University Press (CUP), 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, mdp, 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, mdp, 2014, 2 (1), pp.23-43. ⟨hal-01152429⟩
Journal: Mathematics and Mechanics of Complex Systems
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Sedimentation-induced tether on a settling vesicle. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, American Physical Society, 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, American Physical Society, 2013, 88, pp.010702. ⟨10.1103/PhysRevE.88.010702⟩. ⟨hal-00997686⟩
Journal: Physical Review E : Statistical, Nonlinear, and Soft Matter Physics
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, American Physical Society, 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, American Physical Society, 2013, 88 (1), pp.012208. ⟨10.1103/PhysRevE.88.012208⟩. ⟨hal-00905562⟩
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, European Geosciences Union (EGU), 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, European Geosciences Union (EGU), 2013, 20 (2), pp.189-198. ⟨10.5194/npg-20-189-2013⟩. ⟨hal-01464721⟩
H. Hchaichi, Hamza Elfil, Pierrette Guichardon, Ahmed Hannachi. Scaling tendency assessment in reverse osmosis modules. Desalination and Water Treatment, FHF, 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, FHF, 2013, 51 (4-6), pp.892-898. ⟨10.1080/19443994.2012.715410⟩. ⟨hal-01464722⟩
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
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, Elsevier, 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, Elsevier, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Settling of a vesicle in the limit of quasi-spherical shapes. Journal of Fluid Mechanics, Cambridge University Press (CUP), 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, Cambridge University Press (CUP), 2012, 690, pp.227-261. ⟨10.1017/jfm.2011.427⟩. ⟨hal-00997678⟩
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, Elsevier, 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, Elsevier, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩
A. Leybros, A. Roubaud, Pierrette Guichardon, Olivier Boutin. Supercritical water oxidation of ion exchange resins in a stirred reactor: numerical modelling. Chemical Engineering Science, Elsevier, 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, Elsevier, 2012, 69 (1), pp.170-180. ⟨10.1016/j.ces.2011.10.016⟩. ⟨hal-00993023⟩
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, Elsevier, 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, Elsevier, 2012, 65, pp.25-31. ⟨10.1016/j.supflu.2012.02.019⟩. ⟨hal-00992976⟩
Gwen Boedec, Marc Leonetti, Marc Jaeger. 3D vesicle dynamics simulations with a linearly triangulated surface. Journal of Computational Physics, Elsevier, 2011, 230 (4), pp.1020-1034. ⟨10.1016/j.jcp.2010.10.021⟩. ⟨hal-00717365⟩ Plus de détails...
Simulations of biomembranes have gained an increasing interest in the past years. specificities of these membranes propose new challenges for the numerics. In particular, vesicle dynamics are governed by bending forces as well as a surface incompressibility constraint. A method to compute the bending force density resultant onto piecewise linearly triangulated surface meshes is described. This method is coupled with a boundary element method solver for inner and outer fluids, to compute vesicle dynamics under external flows. The surface incompressibility constraint is satisfied by the construction of a projection operator.
Gwen Boedec, Marc Leonetti, Marc Jaeger. 3D vesicle dynamics simulations with a linearly triangulated surface. Journal of Computational Physics, Elsevier, 2011, 230 (4), pp.1020-1034. ⟨10.1016/j.jcp.2010.10.021⟩. ⟨hal-00717365⟩
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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 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, Elsevier, 2009, 52 (19-20), pp.4211-4220. ⟨10.1016/j.ijheatmasstransfer.2009.04.008⟩. ⟨hal-01307193⟩
Journal: International Journal of Heat and Mass Transfer
Sunita Chatkaew, Marc Georgelin, Marc Jaeger, Marc Leonetti. Dynamics of Vesicle Unbinding under axisymmetric flow. Physical Review Letters, American Physical Society, 2009, 103 (24), pp.248103. ⟨10.1103/PhysRevLett.103.248103⟩. ⟨hal-00440220⟩ Plus de détails...
Sunita Chatkaew, Marc Georgelin, Marc Jaeger, Marc Leonetti. Dynamics of Vesicle Unbinding under axisymmetric flow. Physical Review Letters, American Physical Society, 2009, 103 (24), pp.248103. ⟨10.1103/PhysRevLett.103.248103⟩. ⟨hal-00440220⟩
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, Elsevier, 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, Elsevier, 2008, 41 (12), pp.2094-2100. ⟨10.1016/j.asr.2007.07.016⟩. ⟨hal-01307161⟩
Juan-David Llamas, Cédric Pérat, François Lesage, Mathieu Weber, Umberto d'Ortona, et al.. Wire mesh tomography applied to trickle beds : a new way to study liquid maldistribution. Chemical Engineering and Processing: Process Intensification, Elsevier, 2008, 47, pp.1765-1770. ⟨10.1016/j.cep.2007.09.017⟩. ⟨hal-00189354⟩ Plus de détails...
Two sets of wire mesh tomography sensors have been developed for the study of liquid maldistribution in trickle bed reactors. The technique, based on the one used by Prasser et al. [H.M. Prasser, A. Böttger, J. Zschau, A new electrode-mesh tomograph for gas-liquid flows, Flow Meas. Instrum. 9 (1998), 111-119] in bubble columns, uses two horizontal planes of wires placed at fixed bed depths to measure the presence of a conductive liquid between them. Being only slightly invasive, the conceived wire mesh tomography device allows estimation of liquid concentration over a cross-sectional area of the column with a spatial resolution of 313 pixels. Examples of wire mesh tomography measurements inside a trickle bed reactor using different liquid distributors are presented here. Results are satisfying and wire mesh tomography appears to be a promising technique for the study of liquid maldistribution in trickle beds of non-porous particles.
Juan-David Llamas, Cédric Pérat, François Lesage, Mathieu Weber, Umberto d'Ortona, et al.. Wire mesh tomography applied to trickle beds : a new way to study liquid maldistribution. Chemical Engineering and Processing: Process Intensification, Elsevier, 2008, 47, pp.1765-1770. ⟨10.1016/j.cep.2007.09.017⟩. ⟨hal-00189354⟩
Journal: Chemical Engineering and Processing: Process Intensification
G. Félix, V. Falk, Umberto d'Ortona. Granular flows in a rotating drum : the scaling law between velocity and thickness of the flow. European Physical Journal E: Soft matter and biological physics, EDP Sciences: EPJ, 2007, 22 (1), pp.25-31. ⟨10.1140/epje/e2007-00002-5⟩. ⟨hal-00275307⟩ Plus de détails...
The flow of dry granular material in a half-filled rotating drum is studied. The thickness of the flowing zone is measured for several rotation speeds, drum sizes and beads sizes (size ratio between drum and beads ranging from 47 to 7400). Varying the rotation speed, a scaling law linking mean velocity vs. thickness of the flow, v ∼hm, is deduced for each couple (beads, drum). The obtained exponent m is not always equal to 1, the value previously reported for a drum in litterature, but varies with the geometry of the system. For small size ratios, exponents higher than 1 are obtained due to a saturation of the flowing zone thickness. The exponent of the power law decreases with the size ratio, leading to exponents lower than 1 for high size ratios. These exponents imply that the velocity gradient of a dry granular flow in a rotating drum is not constant. More fundamentally, these results show that the flow of a granular material in a rotating drum is very sensible to the geometry, and that. the deduction of the "rheology" of a granular medium flowing in such a geometry is not obvious.
G. Félix, V. Falk, Umberto d'Ortona. Granular flows in a rotating drum : the scaling law between velocity and thickness of the flow. European Physical Journal E: Soft matter and biological physics, EDP Sciences: EPJ, 2007, 22 (1), pp.25-31. ⟨10.1140/epje/e2007-00002-5⟩. ⟨hal-00275307⟩
Journal: European Physical Journal E: Soft matter and biological physics
P. Guichardon, Philippe Moulin, F. Tosini, L. Cara, F. Charbit. Comparative study of semi-solid liposome purification by different separation methods. Separation and Purification Technology, Elsevier, 2005, 41 (2), pp.123 - 131. ⟨10.1016/j.seppur.2004.01.010⟩. ⟨hal-01916627⟩ Plus de détails...
P. Guichardon, Philippe Moulin, F. Tosini, L. Cara, F. Charbit. Comparative study of semi-solid liposome purification by different separation methods. Separation and Purification Technology, Elsevier, 2005, 41 (2), pp.123 - 131. ⟨10.1016/j.seppur.2004.01.010⟩. ⟨hal-01916627⟩
M. Jaeger, M. Carin. The Front-Tracking ALE Method: Application to a Model of the Freezing of Cell Suspensions. Journal of Computational Physics, Elsevier, 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, Elsevier, 2002, 179 (2), ⟨10.1006/jcph.2002.7084⟩. ⟨hal-01282007⟩
D.V. Lyubimov, T. P. Lyubimova, R.V. Skuridin, G. Chen, B. Roux. Numerical investigation of meniscus deformation and flow in an isothermal liquid bridge subject to high-frequency vibrations under zero gravity conditions. Computers and Fluids, Elsevier, 2002, 31, pp.663-682. ⟨10.1016/S0045-7930(01)00078-0⟩. ⟨hal-01307320⟩ Plus de détails...
This paper deals with meniscus deformation and flow in an isothermal liquid bridge maintained between two circular rods, when one rod is subject to axial monochromatic vibrations. It concerns a fundamental aspect of the problem of crystal growth from melt by the floating-zone technique which is often considered in weightlessness conditions. In the absence of vibrations the bridge is cylindrical; but due to vibration the mean shape of the meniscus is no more cylindrical and the meniscus oscillates around this mean shape. Two models are developed. First, we take into account the pulsating deformations of the meniscus (free surface), but we assume that the mean shape of meniscus remains cylindrical (i.e., we neglect the influence of vibration on this mean shape). For this simple case, a solution of the problem for the pulsating meniscus deformations and the pulsating velocity field is found in explicit form. For the mean flow, the problem is solved numerically by a finite-difference method. The calculations demonstrate the contribution of two basic mechanisms of mean flow generation due to vibrations, related to the generation of mean vorticity in the viscous boundary layer near the rigid boundaries and surface-wave propagation at a free surface. The intensity of the mean flow induced by surface waves is found to be sharply increasing when the vibration frequency approaches the resonance values that are determined from the explicit form of the solution of pulsation problem. In the second model, we take into account both pulsating and mean deformations of the meniscus. The governing equations for the potential of pulsating velocity and mean velocity, and for the pressure, are solved by using a finite-difference method and a boundary-fitted curvilinear coordinate system fitting the free surface.
D.V. Lyubimov, T. P. Lyubimova, R.V. Skuridin, G. Chen, B. Roux. Numerical investigation of meniscus deformation and flow in an isothermal liquid bridge subject to high-frequency vibrations under zero gravity conditions. Computers and Fluids, Elsevier, 2002, 31, pp.663-682. ⟨10.1016/S0045-7930(01)00078-0⟩. ⟨hal-01307320⟩
M. Carin, M. Jaeger. Numerical simulation of the interaction of biological cells with an ice front during freezing. European Physical Journal: Applied Physics, EDP Sciences, 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, EDP Sciences, 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, Elsevier, 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, Elsevier, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩
A. Boukamel, Stéphane Méo, Olivier Débordes, Marc Jaeger. A thermo-viscoelastic model for elastomeric behaviour and its numerical application. Archive of Applied Mechanics, Springer Verlag, 2001, 71, pp.785-801. ⟨10.1007/s004190100191⟩. ⟨hal-01236417⟩ Plus de détails...
This paper presents a model of thermo-mechanical behaviour of viscoelastic elastomers under large strain. A formulation is proposed with a generalisation to large strain of the Poynting–Thomson rheological model. A finite element formulation is then exposed taking the incompressibility constraint for mechanical equilibrium into account. On the thermomechanical coupling aspect, an algorithm of time discretisation is proposed with two time scales corresponding respectively to mechanical and thermal behaviours. Finally, an application for the simulation of a double-shearing test is presented with an analysis of parameters' influence and a comparison between numerical and experimental results.
A. Boukamel, Stéphane Méo, Olivier Débordes, Marc Jaeger. A thermo-viscoelastic model for elastomeric behaviour and its numerical application. Archive of Applied Mechanics, Springer Verlag, 2001, 71, pp.785-801. ⟨10.1007/s004190100191⟩. ⟨hal-01236417⟩
A Decarlis, Marc Jaeger. Effective thermal conductivity of heterogeneous two-phase material using the self-consistent finite element method. Scripta Materialia, Elsevier, 2001, 44 (8-9), ⟨10.1016/S1359-6462(01)00830-2⟩. ⟨hal-01282039⟩ Plus de détails...
Advanced materials often involve the mixture of a second phase material (the inclusions) in a host phase (the matrix). Indeed, materials with very specific properties can be synthesized by controlling the nature of each phase as well as the shape and spatial distribution of the inclusions. Therefore, homogenization tools yielding accurate effective transport properties are needed. We present a numerical extension of a pure analytical treatment of the problem, namely the self-consistent method.
A Decarlis, Marc Jaeger. Effective thermal conductivity of heterogeneous two-phase material using the self-consistent finite element method. Scripta Materialia, Elsevier, 2001, 44 (8-9), ⟨10.1016/S1359-6462(01)00830-2⟩. ⟨hal-01282039⟩
Eric Serre, Patrick Bontoux, Richard Kotarba. Numerical Simulation of the transition in three-dimensional rotating flows with walls. Boundary layer instabilities. International Journal of Computational Fluid Dynamics, Taylor & Francis, 2001, 5 (2), pp.873-879. ⟨hal-01023068⟩ Plus de détails...
Eric Serre, Patrick Bontoux, Richard Kotarba. Numerical Simulation of the transition in three-dimensional rotating flows with walls. Boundary layer instabilities. International Journal of Computational Fluid Dynamics, Taylor & Francis, 2001, 5 (2), pp.873-879. ⟨hal-01023068⟩
Journal: International Journal of Computational Fluid Dynamics
Eric Serre, Patrick Bontoux, Richard Kotarba. Numerical simulation of the transition in three-dimensional rotating flows with walls : boundary layers instabilities. International Journal of Computational Fluid Dynamics, Taylor & Francis, 2001, 5, pp.2. ⟨hal-00835770⟩ Plus de détails...
The purpose of this article is the direct numerical simulation (DNS) of the complex phenomena that precede the transition to turbulence inside a cavity subjected to rotation. The configurations of cylindrical cavities subjected to a radial throughflow or to a differential rotation of the walls are relevant to rotating machinery devices. At a high rotation rate, the DNS exhibits instability patterns arising inside the thin layers close to the disks. The efficient spectral solver is based on a Chebyshev-Fourier approximation. For large aspect ratio and at high Reynolds number, an instability occurs inside the Ekman and Bödewadt layers in the form of annular and spiral vortices that are characteristic of type I and type II instabilities.
Eric Serre, Patrick Bontoux, Richard Kotarba. Numerical simulation of the transition in three-dimensional rotating flows with walls : boundary layers instabilities. International Journal of Computational Fluid Dynamics, Taylor & Francis, 2001, 5, pp.2. ⟨hal-00835770⟩
Journal: International Journal of Computational Fluid Dynamics
Gang Chen, Stephan E. Belcher. Effects of Long Waves on Wind-Generated Waves. Journal of Physical Oceanography, American Meteorological Society, 2000, 30 (9), pp.2246-2256. ⟨10.1175/1520-0485(2000)0302.0.CO;2⟩. ⟨hal-01307127⟩ Plus de détails...
A model is developed to explain the observation made in several laboratory experiments that short wind-generated waves are suppressed by a train of long, mechanically generated waves. A sheltering mechanism is responsible for generation of the short wind waves, by which wave growth is proportional to the local turbulent wind stress. Hence, if the turbulent wind stress near the surface is reduced by the long wave, then the short wind wave amplitude, and hence also the energy in the short waves at a given fetch, is lower than in the absence of long wave. A quantitative model of this process is formulated to examine the ratios of the growth rate and the total energy density of wind waves with and without a long wave, which is shown to agree reasonably well with the laboratory experiments. The model also explains why this suppression of wind waves by a very long swell is not observed in the ocean where the effects of swell on wind waves are extremely difficult to detect. In the model, the reduction in the turbulent wind stress by the long wave is largest for small values of C L /u * (where C L is the phase speed of the long wave and u * is the friction velocity of the wind). When this ratio is larger than about 25 (typical of ocean swell), both the reduction of the turbulent wind stress by the long wave and, consequently, the reduction in the total energy density of the wind waves are very small, which explains why this phenomenon has not yet been observed on the ocean.
Gang Chen, Stephan E. Belcher. Effects of Long Waves on Wind-Generated Waves. Journal of Physical Oceanography, American Meteorological Society, 2000, 30 (9), pp.2246-2256. ⟨10.1175/1520-0485(2000)0302.0.CO;2⟩. ⟨hal-01307127⟩
A. Decarlis, M. Jaeger, Roland Martin. Determination of the Effective Thermal Conductivity Tensor of Heterogeneous Media Using a Self-Consistent Finite Element Method: Application to the Pseudo-percolation Thresholds of Mixtures Containing Nonspherical Inclusions. Journal of Heat Transfer, American Society of Mechanical Engineers, 2000, 122 (1), ⟨10.1115/1.521451⟩. ⟨hal-01282067⟩ Plus de détails...
This paper concerns the determination of the effective thermal conductivity of heterogeneous media with randomly dispersed inclusions. Inclusions of arbitrary shape can be considered since the self-consistent problem is solved numerically with the finite element method. Results for many different cases of heterogeneous media with axially symmetrical inclusions are presented. Moreover, the influence of the inclusion's shape on the pseudo-percolation threshold is investigated.
A. Decarlis, M. Jaeger, Roland Martin. Determination of the Effective Thermal Conductivity Tensor of Heterogeneous Media Using a Self-Consistent Finite Element Method: Application to the Pseudo-percolation Thresholds of Mixtures Containing Nonspherical Inclusions. Journal of Heat Transfer, American Society of Mechanical Engineers, 2000, 122 (1), ⟨10.1115/1.521451⟩. ⟨hal-01282067⟩
Marc Jaeger, Muriel Carin, Marc Medale, Gretar Tryggvason. The Osmotic Migration of Cells in a Solute Gradient. Biophysical Journal, Biophysical Society, 1999, 77 (3), ⟨10.1016/S0006-3495(99)76977-8⟩. ⟨hal-01282080⟩ Plus de détails...
The effect of a nonuniform solute concentration on the osmotic transport of water through the boundaries of a simple model cell is investigated. A system of two ordinary differential equations is derived for the motion of a single cell in the limit of a fast solute diffusion, and an analytic solution is obtained for one special case. A two-dimensional finite element model has been developed to simulate the more general case (finite diffusion rates, solute gradient induced by a solidification front). It is shown that the cell moves to regions of lower solute concentration due to the uneven flux of water through the cell boundaries. This mechanism has apparently not been discussed previously. The magnitude of this effect is small for red blood cells, the case in which all of the relevant parameters are known. We show, however, that it increases with cell size and membrane permeability, so this effect could be important for larger cells. The finite element model presented should also have other applications in the study of the response of cells to an osmotic stress and for the interaction of cells and solidification fronts. Such investigations are of major relevance for the optimization of cryopreservation processes.
Marc Jaeger, Muriel Carin, Marc Medale, Gretar Tryggvason. The Osmotic Migration of Cells in a Solute Gradient. Biophysical Journal, Biophysical Society, 1999, 77 (3), ⟨10.1016/S0006-3495(99)76977-8⟩. ⟨hal-01282080⟩
Médale Marc, Marc Jaeger, Ahmed Kaiss. Finite element analysis of the action of buoyancy-induced and thermocapillary flow on the melting of tin in a 2D square cavity. Computer Assisted Mechanics and Engineering Sciences, 1999. ⟨hal-01282058⟩ Plus de détails...
A finite element model has been developed for the computation of melting/solidifying process under the combined action of buoyancy and surface tension forces. Validated on the square cavity benchmark of Gobin and Le Quéré (Bertrand et al. [1], Gobin and Le Quéré [2]), the numerical model is used to extend this previous analysis to the free surface case where surface tension can drive the flow (capillary flow). A comparison of the results obtained for three types of boundary conditions applied at the top of the melting pool is performed. It shows that in the studied case of tin where the thermal Bond number is moderated (Bo=200), the flow is still mainly dominated by buoyancy effect as long as the melted pool is deep enough like in the square cavity case of the above mentioned benchmark.
Médale Marc, Marc Jaeger, Ahmed Kaiss. Finite element analysis of the action of buoyancy-induced and thermocapillary flow on the melting of tin in a 2D square cavity. Computer Assisted Mechanics and Engineering Sciences, 1999. ⟨hal-01282058⟩
Journal: Computer Assisted Mechanics and Engineering Sciences
Gang Chen, Christian Kharif, Stéphane Zaleski, Jie Li. Two-dimensional Navier–Stokes simulation of breaking waves. Physics of Fluids, American Institute of Physics, 1999, 11 (1), pp.121-133. ⟨10.1063/1.869907⟩. ⟨hal-01307123⟩ Plus de détails...
Numerical simulations describing plunging breakers including the splash-up phenomenon are presented. The motion is governed by the classical, incompressible, two-dimensional Navier–Stokes equation. The numerical modeling of this two-phase flow is based on a piecewise linear version of the volume of fluid method. Capillary effects are taken into account such as a nonisotropic stress tensor concentrated near the interface. Results concerning the time evolution of liquid–gas interface and velocity field are given for short waves, showing how an initial steep wave undergoes breaking and successive splash-up cycles. Breaking processes including overturning, splash-up and gas entrainment, and breaking induced vortex-like motion beneath the surface and energy dissipation, are presented and discussed. It is found that strong vorticities are generated during the breaking process, and that more than 80% of the total pre-breaking wave energy is dissipated within three wave periods. The numerical results are compared with some laboratory measurements, and a favorable agreement is found.
Gang Chen, Christian Kharif, Stéphane Zaleski, Jie Li. Two-dimensional Navier–Stokes simulation of breaking waves. Physics of Fluids, American Institute of Physics, 1999, 11 (1), pp.121-133. ⟨10.1063/1.869907⟩. ⟨hal-01307123⟩