Publications de l'équipe Thermodynamique Ondes Numérique Interfaces Combustion
2020
Kai Zhang, Salman Verma, Arnaud Trouvé, Aymeric Lamorlette. A study of the canopy effect on fire regime transition using an objectively defined Byram convective number. Fire Safety Journal, Elsevier, 2020, 112, pp.102950. ⟨10.1016/j.firesaf.2020.102950⟩. ⟨hal-02469260⟩ Plus de détails...
Kai Zhang, Salman Verma, Arnaud Trouvé, Aymeric Lamorlette. A study of the canopy effect on fire regime transition using an objectively defined Byram convective number. Fire Safety Journal, Elsevier, 2020, 112, pp.102950. ⟨10.1016/j.firesaf.2020.102950⟩. ⟨hal-02469260⟩
Isabelle Raspo, Evelyne Neau. An empirical correlation for the relative permittivity of liquids in a wide temperature range: application to the modeling of electrolyte systems with a GE/EoS approach.. Fluid Phase Equilibria, Elsevier, 2020, 506, pp.112371. ⟨10.1016/j.fluid.2019.112371⟩. ⟨hal-02325903⟩ Plus de détails...
Relative permittivity, also known as static dielectric constant, is a key property of solvents in electrolyte solutions. It strongly influences the solubility of solutes and, therefore, it can be used as a predictive tool in chemical engineering processes. Relative permittivity also plays an essential role in the modeling of phase equilibria of electrolyte systems, since it is involved in the Debye-Hückel model and in the Mean Spherical Approximation, commonly used to represent long-range interactions between ions. In this paper, we propose a new temperature-dependent correlation for the relative permittivity of liquid water, methanol and ethanol, valid in a wide temperature range, including very high temperatures. Comparison with other literature equations evidenced that the main interest of the proposed correlation is to allow satisfactory predictions of the relative permittivity, not only in the range of validity of other literature models, but also in the high temperature domain, including supercritical temperatures for water. The new correlation is then used with the NRTL-PRA EoS to predict vapor pressure of water with several salts, including single electrolytes and two-salts mixtures; it must be noted that the modeling presented in this work is relevant for any GE/EoS model, since in this case (binary interactions between water and ions being equal to zero), the excess Gibbs energy reduces to the Long-Range term derived from the Pitzer-Debye-Hückel model. A temperature-dependent correction of the solvent relative permittivity is proposed to account for its dependence on ion mole fraction in this Long-Range term. Results thus obtained show that this correction leads to an accurate prediction both: for vapor pressures of aqueous electrolyte solutions in a very wide temperature domain and for the modeling of vapor-liquid equilibria of methanol-water and ethanol-water mixtures with several salts.
Isabelle Raspo, Evelyne Neau. An empirical correlation for the relative permittivity of liquids in a wide temperature range: application to the modeling of electrolyte systems with a GE/EoS approach.. Fluid Phase Equilibria, Elsevier, 2020, 506, pp.112371. ⟨10.1016/j.fluid.2019.112371⟩. ⟨hal-02325903⟩
M. Tayyab, S. Zhao, Y. Feng, Pierre Boivin. Hybrid regularized Lattice-Boltzmann modelling of premixed and non-premixed combustion processes. Combustion and Flame, Elsevier, 2020, 211, pp.173-184. ⟨10.1016/j.combustflame.2019.09.029⟩. ⟨hal-02346556⟩ Plus de détails...
A Lattice-Boltzmann model for low-Mach reactive flows is presented, built upon our recently published model (Comb & Flame, 196, 2018). The approach is hybrid and couples a Lattice-Boltzmann solver for the resolution of mass and momentum conservation and a finite difference solver for the energy and species conservation. Having lifted the constant thermodynamic and transport properties assumptions, the model presented now fully accounts for the classical reactive flow thermodynamic closure: each component is assigned NASA coefficients for calculating its thermodynamic properties. A temperature-dependent viscosity is considered, from which are deduced thermo-diffusive properties via specification of Prandtl and component-specific Schmidt numbers. Another major improvement from our previous contribution is the derivation of an advanced collision kernel compatible of multi-component reactive flows stable in high shear flows. Validation is carried out first on premixed configurations, through simulation of the planar freely propagating flame, the growth of the associated Darrieus-Landau instability and three regimes of flame-vortex interaction. A double shear layer test case including a flow-stabilized diffusion flame is then presented and results are compared with DNS simulations, showing excellent agreement.
M. Tayyab, S. Zhao, Y. Feng, Pierre Boivin. Hybrid regularized Lattice-Boltzmann modelling of premixed and non-premixed combustion processes. Combustion and Flame, Elsevier, 2020, 211, pp.173-184. ⟨10.1016/j.combustflame.2019.09.029⟩. ⟨hal-02346556⟩
Bin Xie, Xi Deng, Shijun Liao. High-fidelity solver on polyhedral unstructured grids for low-Mach number compressible viscous flow. Computer Methods in Applied Mechanics and Engineering, Elsevier, 2019, 357, pp.112584. ⟨10.1016/j.cma.2019.112584⟩. ⟨hal-02467981⟩ Plus de détails...
In this article, we developed an unstructured fluid solver based on finite volume framework for the low-Mach number compressible flows. The present method, so-called FVMS3 (Finite Volume method based on Merged Stencil with 3rd-order reconstruction) formulates two different numerical procedures for spatial reconstructions based on the quadratic polynomial which is performed by using least-square approximations on a merged stencil. In order to improve the reconstruction for discontinuities, we propose the limiting projection approach and smoothness adaptive fitting (SAF) scheme to suppress the numerical oscillation and limit the numerical dissipation. The resulting discretization algorithm that combines FVMS3 with SAF-based limiting projection scheme has third-order accuracy and resolves both smooth and non-smooth solutions with excellent quality. Additionally, a novel numerical model has been proposed by introducing the advection upstream splitting method (AUSM) flux into the pressure projection formulation which results in a unified scheme that works uniformly up to the incompressible limit. The fluid solver that integrates all above new efforts provides high-fidelity solutions for compressible viscous flows particularly for the low Mach regime. The performance of this new solver is verified by numerous benchmark tests. Our numerical results show that the proposed scheme gives accurate and robust solutions for a wide spectrum of test problems.
Bin Xie, Xi Deng, Shijun Liao. High-fidelity solver on polyhedral unstructured grids for low-Mach number compressible viscous flow. Computer Methods in Applied Mechanics and Engineering, Elsevier, 2019, 357, pp.112584. ⟨10.1016/j.cma.2019.112584⟩. ⟨hal-02467981⟩
Journal: Computer Methods in Applied Mechanics and Engineering
Siengdy Tann, Xi Deng, Yuya Shimizu, Raphaël Loubère, Feng Xiao. Solution Property Preserving Reconstruction for Finite Volume Scheme: a BVD+MOOD framework. International Journal for Numerical Methods in Fluids, Wiley, In press, ⟨10.1002/fld.4798⟩. ⟨hal-02397156⟩ Plus de détails...
The purpose of this work is to build a general framework to reconstruct the underlying fields within a Finite Volume (FV) scheme solving a hyperbolic system of PDEs (Partial Differential Equations). In an FV context, the data are piece-wise constants per computational cell and the physical fields are reconstructed taking into account neighbor cell values. These reconstructions are further used to evaluate the physical states usually used to feed a Riemann solver which computes the associated numerical fluxes. The physical field reconstructions must obey some properties linked to the system of PDEs such as the positivity, but also some numerically based ones, like an essentially non-oscillatory behaviour. Moreover, the reconstructions should be high accurate for smooth flows and robust/stable for discontinuous solutions. To ensure a Solution Property Preserving Reconstruction, we introduce a methodology to blend high/low order polynomials and hyperbolic tangent reconstructions. A Boundary Variation Diminishing (BVD) algorithm is employed to select the best reconstruction in each cell. An a posteriori MOOD detection procedure is employed to ensure the positivity by re-computing the rare problematic cells using a robust first-order FV scheme. We illustrate the performance of the proposed scheme via the numerical simulations for some benchmark tests which involve vacuum or near vacuum states, strong discontinuities and also smooth flows. The proposed scheme maintains high accuracy on smooth profile, preserves the positivity and can eliminate the oscillations in the vicinity of discontinuities while maintaining sharper discontinuity with superior solution quality compared to classical high accurate FV schemes.
Siengdy Tann, Xi Deng, Yuya Shimizu, Raphaël Loubère, Feng Xiao. Solution Property Preserving Reconstruction for Finite Volume Scheme: a BVD+MOOD framework. International Journal for Numerical Methods in Fluids, Wiley, In press, ⟨10.1002/fld.4798⟩. ⟨hal-02397156⟩
Journal: International Journal for Numerical Methods in Fluids
E. Joffrin, S. Abduallev, M. Abhangi, P. Abreu, V. Afanasev, et al.. Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall Recent citations. Nuclear Fusion, IOP Publishing, 2019, 59 (11), pp.112021. ⟨10.1088/1741-4326/ab2276⟩. ⟨hal-02459726⟩ Plus de détails...
E. Joffrin, S. Abduallev, M. Abhangi, P. Abreu, V. Afanasev, et al.. Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall Recent citations. Nuclear Fusion, IOP Publishing, 2019, 59 (11), pp.112021. ⟨10.1088/1741-4326/ab2276⟩. ⟨hal-02459726⟩
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , American Physical Society (APS), 2019. ⟨hal-02265484⟩ Plus de détails...
An extended version of the hybrid recursive regularized Lattice-Boltzmann model which incorporates external force is developed to simulate humid air flows with phase change mechanisms under the Boussinesq approximation. Mass and momentum conservation equations are solved by a regu-larized lattice Boltzmann approach well suited for high Reynolds number flows, whereas the energy and humidity related equations are solved by a finite volume approach. Two options are investigated to account for cloud formation in atmospheric flow simulations. The first option considers a single conservation equation for total water and an appropriate invariant variable of temperature. In the other approach, liquid and vapor are considered via two separated equations, and phase transition is accounted for via a relaxation procedure. The obtained models are then systematically validated on four well-established benchmark problems including a double diffusive Rayleigh Bénard convection of humid air, 2D and 3D thermal moist rising bubble under convective atmospheric environment as well as a shallow cumulus convection in framework of large-eddy simulation.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , American Physical Society (APS), 2019. ⟨hal-02265484⟩
G. Farag, Pierre Boivin, P. Sagaut. Interaction of two-dimensional spots with a heat releasing/absorbing shock wave: linear interaction approximation results. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2019, 871, pp.865-895. ⟨10.1017/jfm.2019.324⟩. ⟨hal-02142649⟩ Plus de détails...
The canonical interaction between a two-dimensional weak Gaussian disturbance (en-tropy spot, density spot, weak vortex) with an exothermic/endothermic planar shock wave is studied via the Linear Interaction Approximation. To this end, a unified framework based on an extended Kovasznay decomposition that simultaneously accounts for non-acoustic density disturbances along with a poloidal-toroidal splitting of the vorticity mode and for heat-release is proposed. An extended version of Chu's definition for the energy of disturbances in compressible flows encompassing multi-component mixtures of gases is also proposed. This new definition precludes spurious non-normal phenomena when computing the total energy of extended Kovasznay modes. Detailed results are provided for three cases, along with fully general expressions for mixed solutions that combine incoming vortical, entropy and density disturbances.
G. Farag, Pierre Boivin, P. Sagaut. Interaction of two-dimensional spots with a heat releasing/absorbing shock wave: linear interaction approximation results. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2019, 871, pp.865-895. ⟨10.1017/jfm.2019.324⟩. ⟨hal-02142649⟩
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⟩
Xi Deng, Pierre Boivin, Feng Xiao. A new formulation for two-wave Riemann solver accurate at contact interfaces. Physics of Fluids, American Institute of Physics, 2019, 31 (4), pp.046102. ⟨10.1063/1.5083888⟩. ⟨hal-02100764⟩ Plus de détails...
This study proposes a new formulation for Harten, Lax and van Leer (HLL) type Riemann solver which is capable of solving contact discontinuities accurately but with robustness for strong shock. It is well known that the original HLL, which has incomplete wave structures, is too dissipative to capture contact disconti-nuities accurately. On the other side, contact-capturing approximate Riemann solvers such as Harten, Lax and van Leer with Contact (HLLC) usually suffer from spurious solutions, also called carbuncle phenomenon, for strong shock. In this work a new accurate and robust HLL-type formulation, so-called HLL-BVD (HLL Riemann solver with BVD) is proposed by modifying the original HLL with BVD (boundary variation dimin-shing) algorithm. Instead of explicitly recovering the complete wave structures like the way of HLLC, the proposed method restores the missing contact with a jump-like function. The capability of solving contact discontinuities is further improved by minimizing the inherent dissipation term in HLL. Without modifying the original incomplete wave structures of HLL, the robustness for strong shock has been reserved. Thus the proposed method is free from shock instability problem. The accuracy and robustness of the new method are demonstrated through solving several one-and two-dimensional tests. Results indicate that the new formulation based on two-wave HLL-type Riemann solver is not only capable of capturing contact waves more accurately than the original HLL or HLLC but, most importantly, is free form carbuncle instability for strong shock.
Xi Deng, Pierre Boivin, Feng Xiao. A new formulation for two-wave Riemann solver accurate at contact interfaces. Physics of Fluids, American Institute of Physics, 2019, 31 (4), pp.046102. ⟨10.1063/1.5083888⟩. ⟨hal-02100764⟩
Pierre Boivin, M.A. Cannac, O. Le Metayer. A thermodynamic closure for the simulation of multiphase reactive flows. International Journal of Thermal Sciences, Elsevier, 2019, 137, pp.640-649. ⟨hal-01981954⟩ Plus de détails...
A simple thermodynamic closure for the simulation of multiphase reactive flows is presented. It combines a fully explicit thermodynamic closure appropriate for weakly thermal multiphase flow simulations, with the classical variable heat capacity ideal gas thermodynamic closure, commonly used for reactive flows simulations. Each liquid and gas component is assumed to follow the recent Noble-Abel Stiffened Gas equation of state, fully described by a set of five parameters. A new method for setting these parameters is presented and validated through comparisons with NIST references. Comparisons with a well-known cubic equation of state, Soave-Redlich-Kwong, are also included. The Noble-Abel Stiffened-Gas equation of state is then extended as to cope with variable heat capacity, to make the mixture ther-modynamic closure appropriate for multiphase reactive flows.
Pierre Boivin, M.A. Cannac, O. Le Metayer. A thermodynamic closure for the simulation of multiphase reactive flows. International Journal of Thermal Sciences, Elsevier, 2019, 137, pp.640-649. ⟨hal-01981954⟩
Journal: International Journal of Thermal Sciences
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized thermal lattice Boltzmann model for high subsonic compressible flows. Journal of Computational Physics, Elsevier, 2019, 394, pp.82-99. ⟨hal-02142837⟩ Plus de détails...
A thermal lattice Boltzmann model with a hybrid recursive regularization (HRR) collision operator is developed on standard lattices for simulation of subsonic and sonic compressible flows without shock. The approach is hybrid: mass and momentum conservation equations are solved using a lattice Boltzmann solver, while the energy conservation is solved under entropy form with a finite volume solver. The defect of Galilean invariance related to Mach number is corrected by the third order equilibrium distribution function , supplemented by an additional correcting term and hybrid recursive regularization. The proposed approach is assessed considering the simulation of i) an isentropic vortex convection, ii) a two dimensional acoustic pulse and iii) non-isothermal Gaussian pulse with Ma number in range of 0 to 1. Numerical simulations demonstrate that the flaw in Galilean invari-ance is effectively eliminated by the compressible HRR model. At last, the compressible laminar flows over flat plate at Ma number of 0.3 and 0.87, Reynolds number of 10 5 are considered to validate the capture of viscous and diffusive effects.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized thermal lattice Boltzmann model for high subsonic compressible flows. Journal of Computational Physics, Elsevier, 2019, 394, pp.82-99. ⟨hal-02142837⟩
Isabelle Raspo, Evelyne Neau. An empirical correlation for the relative permittivity of liquids in a wide temperature range: application to the modeling of electrolyte systems with a GE/EoS approach.. Fluid Phase Equilibria, Elsevier, In press. ⟨hal-02325903⟩ Plus de détails...
Relative permittivity, also known as static dielectric constant, is a key property of solvents in electrolyte solutions. It strongly influences the solubility of solutes and, therefore, it can be used as a predictive tool in chemical engineering processes. Relative permittivity also plays an essential role in the modeling of phase equilibria of electrolyte systems, since it is involved in the Debye-Hückel model and in the Mean Spherical Approximation, commonly used to represent long-range interactions between ions. In this paper, we propose a new temperature-dependent correlation for the relative permittivity of liquid water, methanol and ethanol, valid in a wide temperature range, including very high temperatures. Comparison with other literature equations evidenced that the main interest of the proposed correlation is to allow satisfactory predictions of the relative permittivity, not only in the range of validity of other literature models, but also in the high temperature domain, including supercritical temperatures for water. The new correlation is then used with the NRTL-PRA EoS to predict vapor pressure of water with several salts, including single electrolytes and two-salts mixtures; it must be noted that the modeling presented in this work is relevant for any GE/EoS model, since in this case (binary interactions between water and ions being equal to zero), the excess Gibbs energy reduces to the Long-Range term derived from the Pitzer-Debye-Hückel model. A temperature-dependent correction of the solvent relative permittivity is proposed to account for its dependence on ion mole fraction in this Long-Range term. Results thus obtained show that this correction leads to an accurate prediction both: for vapor pressures of aqueous electrolyte solutions in a very wide temperature domain and for the modeling of vapor-liquid equilibria of methanol-water and ethanol-water mixtures with several salts.
Isabelle Raspo, Evelyne Neau. An empirical correlation for the relative permittivity of liquids in a wide temperature range: application to the modeling of electrolyte systems with a GE/EoS approach.. Fluid Phase Equilibria, Elsevier, In press. ⟨hal-02325903⟩
L. Terrei, A. Lamorlette, A. Ganteaume. Modelling the fire propagation from the fuel bed to the lower canopy of ornamental species used in wildland–urban interfaces. International Journal of Wildland Fire, CSIRO Publishing, 2019, 28 (2), pp.113. ⟨10.1071/WF18090⟩. ⟨hal-02176483⟩ Plus de détails...
South-eastern France is strongly affected by wildfires mostly occurring in the wildland-urban interfaces (WUIs). A WUI fire is often initiated in dead surface fuel, then can propagate to shrubs and trees when the lower canopy is close to (or touches) the ground. Whereas a previous study assessed the fire propagation from the fuel bed to the lower canopy of different species used as ornamental vegetation in this region, the objectives of the current work consisted of checking if the modelling of this fire propagation was possible using WFDS (Wildland-Urban Interface Fire Dynamical Simulator) in comparing experimental and modelling results. Experimental and modelling constraints (i. e. branch geometric definition, branch motion due to convection) showed differences in some of the recorded data (such as time to ignition, ignition temperature, mass loss and maximum temperature), but comparisons of variation in mass loss and temperature over time showed that modelling the fire propagation at the scale of a branch was possible if the branch fuel-moisture content remained lower than 25%. For both experiments and modelling, the ranking of species according to their branch flammability highlighted identical groups of species.
L. Terrei, A. Lamorlette, A. Ganteaume. Modelling the fire propagation from the fuel bed to the lower canopy of ornamental species used in wildland–urban interfaces. International Journal of Wildland Fire, CSIRO Publishing, 2019, 28 (2), pp.113. ⟨10.1071/WF18090⟩. ⟨hal-02176483⟩
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Plane-strain waves in nonlinear elastic solids with softening. Wave Motion, Elsevier, 2019, 89, pp.65-78. ⟨hal-02057946⟩ Plus de détails...
Propagation of elastic waves in damaged media (concrete, rocks) is studied theoretically and numerically. Such materials exhibit a nonlinear behavior, with long-time softening and recovery processes (slow dynamics). A constitutive model combining Murnaghan hyperelasticity with the slow dynamics is considered, where the softening is represented by the evolution of a scalar variable. The equations of motion in the Lagrangian framework are detailed. These equations are rewritten as a nonlinear hyperbolic system of balance laws, which is solved numerically using a finite-volume method with flux limiters. Numerical examples illustrate specific features of nonlinear elastic waves, as well as the effect of the material's softening. In particular, the generation of solitary waves in a periodic layered medium is illustrated numerically.
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Plane-strain waves in nonlinear elastic solids with softening. Wave Motion, Elsevier, 2019, 89, pp.65-78. ⟨hal-02057946⟩
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Premixed flame dynamics in presence of mist. Combustion Science and Technology, Taylor & Francis, 2019, 191 (2), pp.197-207. ⟨10.1080/00102202.2018.1453728⟩. ⟨hal-01820207⟩ Plus de détails...
The injection of a water spray within an enclosure prone to explo- sion is reputed to reduce the risk. This strategy for safety improvement is at the root of numerous experiments that have concluded that pre- mixed flame can be extinguished by a sufficient amount of a water aerosol characterized by suitable droplet sizes. On the other hand, certain experiments seemingly indicate that flame speed promotion can be observed when particular water mists are injected within the premixture. To contribute to shed light upon these less than intuitive observa- tions, we propose to study the propagation of a nearly stoichiometric premixed flame within a 2D-lattice of water droplets. Main parameters of investigation are droplet size and droplet inter-distance (or equiva- lently, lattice spacing). When the droplet inter-distance is small, the results confirm that a sufficient amount of water quenches combustion. For larger droplet inter-distance, we observe a flame speed enhance- ment for suitable droplet size. Concomitantly, the flame front folds subjected to Darrieus-Landau instability. The final discussion, which invokes a Sivashinsky-type model equation for DL instability, interprets such a speed promotion in presence of mist as a secondary non-linear enhancement of the flame surface.
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Premixed flame dynamics in presence of mist. Combustion Science and Technology, Taylor & Francis, 2019, 191 (2), pp.197-207. ⟨10.1080/00102202.2018.1453728⟩. ⟨hal-01820207⟩
Nicolas Frangieh, Dominique Morvan, Sofiane Meradji, Gilbert Accary, Oleg Bessonov. Numerical simulation of grassland fires behavior using an implicit physical multiphase model. Fire Safety Journal, Elsevier, 2018, 102, pp.37-47. ⟨10.1016/j.firesaf.2018.06.004⟩. ⟨hal-02114073⟩ Plus de détails...
12 This study reports 3D numerical simulations of the ignition and the propagation of 13 grassland fires. The mathematical model is based on a multiphase formulation and on a 14 homogenization approach that consists in averaging the conservation equations (mass, 15 momentum, energy …) governing the evolution of variables representing the state of the 16 vegetation/atmosphere system, inside a control volume containing both the solid-17 vegetation phase and the surrounding gaseous phase. This preliminary operation results 18 in the introduction of source/sink additional terms representing the interaction between 19 the gaseous phase and the solid-fuel particles. This study was conducted at large scale in 20 grassland because it represents the scale at which the behavior of the fire front presents 21 most similarities with full scale wildfires and also because of the existence of a large 22 number of relatively well controlled experiments performed in Australia and in the 23 United States. The simulations were performed for a tall grass, on a flat terrain, and for 24 six values of the 10-m open wind speed ranged between 1 and 12 m/s. The results are in 25 fairly good agreement with experimental data, with the predictions of operational 26 empirical and semi-empirical models, such as the McArthur model (MK5) in Australia and 27 the Rothermel model (BEHAVE) in USA, as well as with the predictions of other fully 3D 28 physical fire models (FIRETEC and WFDS). The comparison with the literature was 29 mainly based on the estimation of the rate of fire spread (ROS) and of the fire intensity, 30 as well as on the analysis of the fire-front shape. 31 32
Nicolas Frangieh, Dominique Morvan, Sofiane Meradji, Gilbert Accary, Oleg Bessonov. Numerical simulation of grassland fires behavior using an implicit physical multiphase model. Fire Safety Journal, Elsevier, 2018, 102, pp.37-47. ⟨10.1016/j.firesaf.2018.06.004⟩. ⟨hal-02114073⟩
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. LES in a Concentric Annular Pipe: Analysis of Mesh Sensitivity and Wall Pressure Fluctuations. Direct and Large-Eddy Simulation X, pp.93-100, 2018, 978-3-319-63211-7. ⟨hal-02111988⟩ Plus de détails...
Annular pipe flows have varied application in the domains of nuclear reactors, heat exchangers, drilling operations in oil industry etc.
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. LES in a Concentric Annular Pipe: Analysis of Mesh Sensitivity and Wall Pressure Fluctuations. Direct and Large-Eddy Simulation X, pp.93-100, 2018, 978-3-319-63211-7. ⟨hal-02111988⟩
Yongliang Feng, Muhammad Tayyab, Pierre Boivin. A Lattice-Boltzmann model for low-Mach reactive flows. Combustion and Flame, Elsevier, 2018, 196, pp.249 - 254. ⟨10.1016/j.combustflame.2018.06.027⟩. ⟨hal-01832640⟩ Plus de détails...
A new Lattice-Boltzmann model for low-Mach reactive flows is presented. Based on standard lattices, the model is easy to implement, and is the first, to the authors' knowledge, to pass the classical freely propagating flame test case as well as the counterflow diffusion flame, with strains up to extinction. For this presentation, simplified transport properties are considered, each species being assigned a separate Lewis number. In addition, the gas mixture is assumed to be calorically perfect. Comparisons with reference solutions show excellent agreement for mass fraction profiles, flame speed in premixed mixtures, as well as maximum temperature dependence with strain rate in counterflow diffusion flames.
Yongliang Feng, Muhammad Tayyab, Pierre Boivin. A Lattice-Boltzmann model for low-Mach reactive flows. Combustion and Flame, Elsevier, 2018, 196, pp.249 - 254. ⟨10.1016/j.combustflame.2018.06.027⟩. ⟨hal-01832640⟩
Pierre Boivin, Forman Williams. Extension of a wide-range three-step hydrogen mechanism to syngas. Combustion and Flame, Elsevier, 2018, 196, pp.85-87. ⟨10.1016/j.combustflame.2018.05.034⟩. ⟨hal-02112081⟩ Plus de détails...
Previously we have shown how a single species X can be introduced, representing either HO 2 for high-temperature ignition or H 2 O 2 for low-temperature ignition, to develop an algorithm that covers the entire range of ignition, flame-propagation, and combustion conditions, without a significant degradation of accuracy, for hydrogen-air systems. By adding relevant CO chemistry to the hydrogen chemistry, this same approach can be applied to derive a comparably useful four-step reduced-chemistry description for syngas blends that have small enough concentrations of methane, other hydrocarbons , or other reactive species to be dominated by the elementary steps of the H 2 /CO system. The present communication reports the resulting extended algorithm. This work begins with the elementary steps of the detailed chemistry as listed in Table 1. We shall employ the numbering of the steps as given in the table, which identifies the 8 steps that are considered to be reversible and gives fitted parameters for the reverses of those steps.
Pierre Boivin, Forman Williams. Extension of a wide-range three-step hydrogen mechanism to syngas. Combustion and Flame, Elsevier, 2018, 196, pp.85-87. ⟨10.1016/j.combustflame.2018.05.034⟩. ⟨hal-02112081⟩
Dominique Morvan, Gilbert Accary, Sofiane Meradji, Nicolas Frangieh, Oleg Bessonov. A 3D physical model to study the behavior of vegetation fires at laboratory scale. Fire Safety Journal, Elsevier, 2018, 101, pp.39-52. ⟨10.1016/j.firesaf.2018.08.011⟩. ⟨hal-02114685⟩ Plus de détails...
A 3D multi-physical model referred to as “FireStar3D” has been developed in order to predict the behavior of wildfires at a local scale (<500 m). In the continuity of a previous work limited to 2D configurations, this model consists of solving the conservation equations of the coupled system composed of the vegetation and the surrounding gaseous medium. In particular, the model is able to account explicitly for all the mechanisms of degradation of the vegetation (by drying, pyrolysis, and heterogeneous combustion) and the various interactions between the gas mixture (ambient air + pyrolysis and combustion products) and the vegetation cover such as drag force, heat transfer by convection and radiation, and mass transfer. Compared to previous works, some new features were introduced in the modeling of the surface combustion of charcoal, the calculation of the heat transfer coefficient between the solid fuel particles and the surrounding atmosphere, and many improvements were brought to the numerical method to enable affordable 3D simulations. The partial validation of the model was based on some comparisons with experimental data collected at small scale fires carried out in the Missoula Fire Sciences Lab's wind tunnel, through various solid-fuel layers and in well controlled conditions. A relative good agreement was obtained for most of the simulations that were conducted. A parametric study of the dependence of the rate of spread on the wind speed and on the fuelbed characteristics is presented.
Dominique Morvan, Gilbert Accary, Sofiane Meradji, Nicolas Frangieh, Oleg Bessonov. A 3D physical model to study the behavior of vegetation fires at laboratory scale. Fire Safety Journal, Elsevier, 2018, 101, pp.39-52. ⟨10.1016/j.firesaf.2018.08.011⟩. ⟨hal-02114685⟩
Stéphane Abide, Stéphane Viazzo, Isabelle Raspo, Anthony Randriamampianina. Higher-order compact scheme for high-performance computing of stratified rotating flows. Computers and Fluids, Elsevier, 2018, 174, pp.300-310. ⟨10.1016/j.compfluid.2018.07.016⟩. ⟨hal-02111489⟩ Plus de détails...
To take advantage of modern generation computing hardware, a scalable numerical method, based on higher-order compact scheme, is described to solve rotating stratified flows in cylindrical annular domains. An original approach combining 2d-pencil decomposition and reduced Parallel Diagonal Dominant is proposed to improve the parallelization performance during the computation of Poisson/Helmholtz solvers and time explicit terms. The developed technique is validated with respect to analytical solutions, using the method of manufactured solutions, and available data for two specific configurations. The purpose is to demonstrate its ability to correctly capture the flow characteristics in strato-rotational instability and in baroclinic instability with associated small-scale features. Moreover, this code is found to drastically reduce the huge execution times often preventing detailed numerical investigations of these complex phenomena. Strong scaling test is carried out to assess the performance for up to 1024 cores using grid up to 128 × 568 × 568 in radial, axial and azimuthal directions.
Stéphane Abide, Stéphane Viazzo, Isabelle Raspo, Anthony Randriamampianina. Higher-order compact scheme for high-performance computing of stratified rotating flows. Computers and Fluids, Elsevier, 2018, 174, pp.300-310. ⟨10.1016/j.compfluid.2018.07.016⟩. ⟨hal-02111489⟩
Stéphane Abide, Stéphane Viazzo, Isabelle Raspo, Anthony Randriamampianina. Higher-order compact scheme for high-performance computing of stratified rotating flows. Computers and Fluids, Elsevier, 2018, 174, pp.300-310. ⟨10.1016/j.compfluid.2018.07.016⟩. ⟨hal-01896997⟩ Plus de détails...
Xi Deng, Bin Xie, R. Loubère, Yuya Shimizu, Feng Xiao. Limiter-free discontinuity-capturing scheme for compressible gas dynamics with reactive fronts. Computers and Fluids, Elsevier, 2018, 171, pp.1-14. ⟨10.1016/j.compfluid.2018.05.015⟩. ⟨hal-02322017⟩ Plus de détails...
Xi Deng, Bin Xie, R. Loubère, Yuya Shimizu, Feng Xiao. Limiter-free discontinuity-capturing scheme for compressible gas dynamics with reactive fronts. Computers and Fluids, Elsevier, 2018, 171, pp.1-14. ⟨10.1016/j.compfluid.2018.05.015⟩. ⟨hal-02322017⟩
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Reprint of: Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, Elsevier, 2018, 169, pp.213-229. ⟨10.1016/j.compfluid.2018.03.054⟩. ⟨hal-02115861⟩ Plus de détails...
Hot spots ignition and shock to detonation transition modeling in pressed explosives is addressed in the frame of multiphase flow theory. Shock propagation results in mechanical disequilibrium effects between the condensed phase and the gas trapped in pores. Resulting subscale motion creates hot spots at pore scales. Pore collapse is modeled as a pressure relaxation process, during which dissipated power by the ‘configuration’ pressure produces local heating. Such an approach reduces 3D micromechanics and subscale contacts effects to a ‘granular’ equation of state. Hot spots criticity then results of the competition between heat deposition and conductive losses. Heat losses between the hot solid-gas interface at pore's scale and the colder solid core grains are determined through a subgrid model using two energy equations for the solid phase. The conventional energy balance equation provides the volume average solid temperature and a non-conventional energy equation provides the solid core temperature that accounts for shock heating. With the help of these two temperatures and subscale reconstruction, the interface temperature is determined as well as interfacial heat loss. The overall flow model thus combines a full disequilibrium two-phase model for the mean solid-gas flow variables with a subgrid model, aimed to compute local solid-gas interface temperature. Its evolution results of both subscale motion dissipation and conductive heat loss. The interface temperature serves as ignition criterion for the solid material deflagration. There is no subscale mesh, no system of partial differential equations solved at grain scale. The resulting model contains less parameter than existing ones and associates physical meaning to each of them. It is validated against experiments in two very different regimes: Shock to detonation transition, that typically happens in pressure ranges of 50 kbar and shock propagation that involves pressure ranges 10 times higher.
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Reprint of: Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, Elsevier, 2018, 169, pp.213-229. ⟨10.1016/j.compfluid.2018.03.054⟩. ⟨hal-02115861⟩
H Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A Finite-Volume Approach to 1D Nonlinear Elastic Waves: Application to Slow Dynamics. Acta Acustica united with Acustica, Hirzel Verlag, 2018, ⟨10.3813/Aaa.919197⟩. ⟨hal-02111888⟩ Plus de détails...
A numerical method for longitudinal wave propagation in nonlinear elastic solids is presented. Here, we consider polynomial stress-strain relationships, which are widely used in nondestructive evaluation. The large-strain and infinitesimal-strain constitutive laws deduced from Murnaghan'sl aw are detailed, and polynomial expressions are obtained. The Lagrangian equations of motion yield ahyperbolic system of conservation laws. The latter is solved numerically using afi nite-volume method with flux limiters based on Roe linearization. The method is tested on the Riemann problem, which yields nonsmooth solutions. The method is then applied to acontinuum model with one scalar internal variable, accounting for the softening of the material (slowdynamics).
H Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A Finite-Volume Approach to 1D Nonlinear Elastic Waves: Application to Slow Dynamics. Acta Acustica united with Acustica, Hirzel Verlag, 2018, ⟨10.3813/Aaa.919197⟩. ⟨hal-02111888⟩
Mohamed El Bachir Seck, Mihail Garajeu, Renaud Masson. Exact solutions for the effective nonlinear viscoelastic (or elasto-viscoplastic) behaviour of particulate composites under isotropic loading. European Journal of Mechanics - A/Solids, Elsevier, 2018. ⟨hal-02482763⟩ Plus de détails...
We consider a composite sphere which consists of a spherical inclusion embedded in a concentric spherical matrix, the inclusion and matrix phases obeying an isotropic nonlinear vis-coelastic behaviour. For different isotropic loadings (macroscopic stress or dilatation, swelling of the inclusion phase), the general solutions are shown to depend on the shear stress distribution in the matrix. This shear stress distribution is solution of a first-order nonlinear integro-differential equation, regardless of the inclusion viscoplastic behaviour. When the viscous strain rate potentiel in the matrix is a power-law function of the von Mises equivalent stress, closed-form solutions are given for some special cases clearly identified. Full-field calculations of representative volume elements of particulate composites are also reported. For a moderate volume fraction of inclusions, the composite sphere model turns out to be in excellent agreement with these full-field calculations.
Mohamed El Bachir Seck, Mihail Garajeu, Renaud Masson. Exact solutions for the effective nonlinear viscoelastic (or elasto-viscoplastic) behaviour of particulate composites under isotropic loading. European Journal of Mechanics - A/Solids, Elsevier, 2018. ⟨hal-02482763⟩
Mohamad El Houssami, Aymeric Lamorlette, Dominique Morvan, Rory Hadden, Albert Simeoni. Framework for submodel improvement in wildfire modeling. Combustion and Flame, Elsevier, 2018, 190, pp.12-24. ⟨10.1016/j.combustflame.2017.09.038⟩. ⟨hal-02114000⟩ Plus de détails...
An experimental and numerical study was carried out to assess the performance of the different sub-models and parameters used to describe the burning dynamics of wildfires. A multiphase formulation was used and compared to static fires of dried pitch pine needles of different bulk densities. The samples were exposed to an external heat flux of 50 kW/m 2 in the FM Global Fire Propagation Apparatus and subjected to different airflows, providing a controlled environment and repeatable conditions. Sub-models for convective heat transfer, drag forces, and char combustion were investigated to provide mass loss rate, flaming duration, and gas emissions. Good agreement of predicted mass loss rates and heat release rates was achieved, where all these submodels were selected to suit the tested conditions. Simulated flaming times for different flow conditions and different fuel bulk densities compared favorably against experimental measurements. The calculation of the drag forces and the heat transfer coefficient was demonstrated to influence greatly the heating/cooling rate, the degradation rate, and the flaming time. The simulated CO and CO 2 values compared well with experimental data, especially for reproducing the transition between flaming and smoldering. This study complements a previous study made with no flow to propose a systematic approach that can be used to assess the performance of the submodels and to better understand how specific physical phenomena contribute to the wildfire dynamics. Furthermore, this study underlined the importance of selecting relevant submodels and the necessity of introducing relevant subgrid-scale modelling for larger scale simulations.
Mohamad El Houssami, Aymeric Lamorlette, Dominique Morvan, Rory Hadden, Albert Simeoni. Framework for submodel improvement in wildfire modeling. Combustion and Flame, Elsevier, 2018, 190, pp.12-24. ⟨10.1016/j.combustflame.2017.09.038⟩. ⟨hal-02114000⟩
Evelyne Neau, Christophe Nicolas, Laurent Avaullée. Extension of the group contribution NRTL-PRA EoS for the modeling of mixtures containing light gases and alcohols with water and salts. Fluid Phase Equilibria, Elsevier, 2018, 458, pp.194-210. ⟨10.1016/j.fluid.2017.09.028⟩. ⟨hal-01703014⟩ Plus de détails...
The offshore exploitation of petroleum fluids in normal conditions of pressure and temperature of transport and in presence of salt water is concerned with the prevention of gas hydrate formation, generally thanks to continuous injection of inhibitors, or punctual injection of methanol in start-up and shut-down operations. Hence, models of interest should provide both, satisfactory phase equilibrium estimations of hydrocarbon and alcohol mixtures with water and reliable predictions of their behavior in presence of salts.
Evelyne Neau, Christophe Nicolas, Laurent Avaullée. Extension of the group contribution NRTL-PRA EoS for the modeling of mixtures containing light gases and alcohols with water and salts. Fluid Phase Equilibria, Elsevier, 2018, 458, pp.194-210. ⟨10.1016/j.fluid.2017.09.028⟩. ⟨hal-01703014⟩
Richard Saurel, Carlos Pantano. Diffuse-Interface Capturing Methods for Compressible Two-Phase Flows. Annual Review of Fluid Mechanics, Annual Reviews, 2018, 50 (1), pp.105 - 130. ⟨10.1146/annurev-fluid-122316-050109⟩. ⟨hal-02115896⟩ Plus de détails...
Simulation of compressible flows became a routine activity with the appearance of shock-/contact-capturing methods. These methods can determine all waves, particularly discontinuous ones. However, additional difficulties may appear in two-phase and multimaterial flows due to the abrupt variation of thermodynamic properties across the interfacial region, with discontinuous thermodynamical representations at the interfaces. To overcome this difficulty, researchers have developed augmented systems of governing equations to extend the capturing strategy. These extended systems, reviewed here, are termed diffuse-interface models, because they are designed to compute flow variables correctly in numerically diffused zones surrounding interfaces. In particular, they facilitate coupling the dynamics on both sides of the (diffuse) interfaces and tend to the proper pure fluid–governing equations far from the interfaces. This strategy has become efficient for contact interfaces separating fluids that are governed by different equations of state, in the presence or absence of capillary effects, and with phase change. More sophisticated materials than fluids (e.g., elastic–plastic materials) have been considered as well.
Richard Saurel, Carlos Pantano. Diffuse-Interface Capturing Methods for Compressible Two-Phase Flows. Annual Review of Fluid Mechanics, Annual Reviews, 2018, 50 (1), pp.105 - 130. ⟨10.1146/annurev-fluid-122316-050109⟩. ⟨hal-02115896⟩
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⟩
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A finite-volume approach to 1D nonlinear elastic waves: Application to slow dynamics. Acta Acustica united with Acustica, Hirzel Verlag, 2018, 104, pp.561-570. ⟨hal-01806373⟩ Plus de détails...
A numerical method for longitudinal wave propagation in nonlinear elastic solids is presented. Here, we consider polynomial stress-strain relationships, which are widely used in nondestructive evaluation. The large-strain and infinitesimal-strain constitutive laws deduced from Murnaghan's law are detailed , and polynomial expressions are obtained. The Lagrangian equations of motion yield a hyperbolic system of conservation laws. The latter is solved numerically using a finite-volume method with flux limiters based on Roe linearization. The method is tested on the Riemann problem, which yields nonsmooth solutions. The method is then applied to a continuum model with one scalar internal variable, accounting for the softening of the material (slow dynamics).
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A finite-volume approach to 1D nonlinear elastic waves: Application to slow dynamics. Acta Acustica united with Acustica, Hirzel Verlag, 2018, 104, pp.561-570. ⟨hal-01806373⟩
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Modeling longitudinal wave propagation in nonlinear viscoelastic solids with softening. International Journal of Solids and Structures, Elsevier, 2018, 141-142, pp.35-44. ⟨10.1016/j.ijsolstr.2018.02.009⟩. ⟨hal-01701624⟩ Plus de détails...
A model for longitudinal wave propagation in rocks and concrete is presented. Such materials are known to soften under a dynamic loading, i.e. the speed of sound diminishes with forcing amplitudes. Also known as slow dynamics, the softening of the material is not instantaneous. Based on continuum mechanics with internal variables of state, a new formulation is proposed, which accounts for nonlinear Zener viscoelasticity and softening. A finite-volume method using Roe linearization is developed for the system of partial differential equations so-obtained. The method is used to carry out resonance simulations, and its performance is assessed in the linear viscoelastic case. Qualitative agreement with experimental results of nonlinear ultrasound spectroscopy (NRUS) and dynamic acousto-elastic testing (DAET) is obtained.
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Modeling longitudinal wave propagation in nonlinear viscoelastic solids with softening. International Journal of Solids and Structures, Elsevier, 2018, 141-142, pp.35-44. ⟨10.1016/j.ijsolstr.2018.02.009⟩. ⟨hal-01701624⟩
Journal: International Journal of Solids and Structures
Dominique Morvan. Comprendre et prévenir les feux de végétation. Université Grenoble Alpes. Encyclopédie de l’Environnement, 2018. ⟨hal-01678486⟩ Plus de détails...
Dominique Morvan, Nicolas Frangieh. Wildland fires behaviour: wind effect versus Byram’s convective number and consequences upon the regime of propagation. International Journal of Wildland Fire, CSIRO Publishing, 2018, 27 (9), pp.636. ⟨10.1071/Wf18014⟩. ⟨hal-02114689⟩ Plus de détails...
With fuel moisture content and slope, wind velocity (U W) is one of the major physical parameters that most affects the behaviour of wildland fires. The aim of this short paper was to revisit the relationship between the rate of spread (ROS) and the wind velocity, through the role played by the two forces governing the trajectory of the flame front and the plume, i.e. the buoyancy of the plume and the inertia due to wind. A large set of experimental data (at field and laboratory scale) from the literature was analysed, by introducing the ratio between these two forces, namely Byram's convective number N C and considering the relationship between the fire ROS/wind speed ratio and Byram's number. This short note was also an opportunity to make a point on particular issues, such as the existence of two regimes of propagation of surface fires (wind-driven fire vs plume-dominated fire), the relative importance of the two modes of heat transfer (by convection and radiation) on the propagation of a fire front, and others scientific debates animating the wildland fire community.
Dominique Morvan, Nicolas Frangieh. Wildland fires behaviour: wind effect versus Byram’s convective number and consequences upon the regime of propagation. International Journal of Wildland Fire, CSIRO Publishing, 2018, 27 (9), pp.636. ⟨10.1071/Wf18014⟩. ⟨hal-02114689⟩
Aymeric Lamorlette, Mohamad El Houssami, Dominique Morvan. An improved non-equilibrium model for the ignition of living fuel. International Journal of Wildland Fire, CSIRO Publishing, 2018, 27 (1), pp.29-41. ⟨10.1071/Wf17020⟩. ⟨hal-02114417⟩ Plus de détails...
This paper deals with the modelling of living fuel ignition, suggesting that an accurate description using a multiphase formulation requires consideration of a thermal disequilibrium within the vegetation particle, between the solid (wood) and the liquid (sap). A simple model at particle scale is studied to evaluate the flux distribution between phases in order to split the net flux on the particles into the two sub-phases. An analytical solution for the split function is obtained from this model and is implemented in ForestFireFOAM, a computational fluid dynamics (CFD) solver dedicated to vegetation fire simulations, based on FireFOAM. Using this multiphase formulation, simulations are run and compared with existing data on living fuel flammability. The following aspects were considered: fuel surface temperature, ignition, flaming combustion time, mean and peak heat release rate (HRR). Acceptable results were obtained, suggesting that the thermal equilibrium might not be an acceptable assumption to properly model ignition of living fuel.
Aymeric Lamorlette, Mohamad El Houssami, Dominique Morvan. An improved non-equilibrium model for the ignition of living fuel. International Journal of Wildland Fire, CSIRO Publishing, 2018, 27 (1), pp.29-41. ⟨10.1071/Wf17020⟩. ⟨hal-02114417⟩
William Mell, Albert Simeoni, Dominique Morvan, J. Kevin Hiers, Nicholas Skowronski, et al.. Clarifying the meaning of mantras in wildland fire behaviour modelling: reply to Cruz et al. (2017). International Journal of Wildland Fire, CSIRO Publishing, 2018, 27 (11), pp.770. ⟨10.1071/Wf18106⟩. ⟨hal-02114662⟩ Plus de détails...
In a recent communication, Cruz et al. (2017) called attention to several recurring statements (mantras) in the wildland fire literature regarding empirical and physical fire behaviour models. Motivated by concern that these mantras have not been fully vetted and are repeated blindly, Cruz et al. (2017) sought to verify five mantras they identify. This is a worthy goal and here we seek to extend the discussion and provide clarification to several confusing aspects of the Cruz et al. (2017) communication. In particular, their treatment of what they call physical models is inconsistent, neglects to reference current research activity focussed on combined experimentation and model development, and misses an opportunity to discuss the potential use of physical models to fire behaviour outside the scope of empirical approaches.
William Mell, Albert Simeoni, Dominique Morvan, J. Kevin Hiers, Nicholas Skowronski, et al.. Clarifying the meaning of mantras in wildland fire behaviour modelling: reply to Cruz et al. (2017). International Journal of Wildland Fire, CSIRO Publishing, 2018, 27 (11), pp.770. ⟨10.1071/Wf18106⟩. ⟨hal-02114662⟩
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small-scale waves within the Stewartson layers of a thermally driven rotating annulus. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2018, 841, pp.380 - 407. ⟨10.1017/jfm.2018.10⟩. ⟨hal-02116196⟩ Plus de détails...
We report on small-scale instabilities in a thermally driven rotating annulus filled with a liquid with moderate Prandtl number. The study is based on direct numerical simulations and an accompanying laboratory experiment. The computations are performed independently with two different flow solvers, that is, first, the non-oscillatory forward-in-time differencing flow solver EULAG and, second, a higher-order finite-difference compact scheme (HOC). Both branches consistently show the occurrence of small-scale patterns at both vertical sidewalls in the Stewartson layers of the annulus. Small-scale flow structures are known to exist at the inner sidewall. In contrast, short-period waves at the outer sidewall have not yet been reported. The physical mechanisms that possibly trigger these patterns are discussed. We also debate whether these small-scale structures are a gravity wave signal.
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small-scale waves within the Stewartson layers of a thermally driven rotating annulus. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2018, 841, pp.380 - 407. ⟨10.1017/jfm.2018.10⟩. ⟨hal-02116196⟩
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, Elsevier, 2017, 159, pp.95 - 111. ⟨10.1016/j.compfluid.2017.09.006⟩. ⟨hal-01707909⟩ Plus de détails...
Hot spots ignition and shock to detonation transition modeling in pressed explosives is addressed in the frame of multiphase flow theory. Shock propagation results in mechanical disequilibrium effects between the condensed phase and the gas trapped in pores. Resulting subscale motion creates hot spots at pore scales. Pore collapse is modeled as a pressure relaxation process, during which dissipated power by the ‘configuration’ pressure produces local heating. Such an approach reduces 3D micromechanics and subscale contacts effects to a ‘granular’ equation of state. Hot spots criticity then results of the competition between heat deposition and conductive losses. Heat losses between the hot solid-gas interface at pore's scale and the colder solid core grains are determined through a subgrid model using two energy equations for the solid phase. The conventional energy balance equation provides the volume average solid temperature and a non-conventional energy equation provides the solid core temperature that accounts for shock heating. With the help of these two temperatures and subscale reconstruction, the interface temperature is determined as well as interfacial heat loss. The overall flow model thus combines a full disequilibrium two-phase model for the mean solid-gas flow variables with a subgrid model, aimed to compute local solid-gas interface temperature. Its evolution results of both subscale motion dissipation and conductive heat loss. The interface temperature serves as ignition criterion for the solid material deflagration. There is no subscale mesh, no system of partial differential equations solved at grain scale. The resulting model contains less parameter than existing ones and associates physical meaning to each of them. It is validated against experiments in two very different regimes: Shock to detonation transition, that typically happens in pressure ranges of 50 kbar and shock propagation that involves pressure ranges 10 times higher.
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, Elsevier, 2017, 159, pp.95 - 111. ⟨10.1016/j.compfluid.2017.09.006⟩. ⟨hal-01707909⟩
Alexandre Chiapolino, Richard Saurel, Boniface Nkonga. Sharpening diffuse interfaces with compressible fluids on unstructured meshes. Journal of Computational Physics, Elsevier, 2017, 340, pp.389-417. ⟨hal-01589124⟩ Plus de détails...
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. Comparative study of the contribution of various PWR spacer grid components to hydrodynamic and wall pressure characteristics. Nuclear Engineering and Design, Elsevier, 2017, 317, pp.22 - 43. ⟨10.1016/j.nucengdes.2017.03.011⟩. ⟨hal-01590274⟩ Plus de détails...
Flow-induced vibrations in a pressurized water reactor (PWR) core can cause fretting wear in fuel rods. These vibrations can compromise safety of a nuclear reactor. So, it is necessary to know the random fluctuating forces acting on the rods which cause these vibrations. In this paper, simplified 3D models like square spacer grid, circular spacer grid and symmetric mixing vanes have been used inside an annular pipe. Hydrodynamic and wall pressure characteristics are evaluated using large eddy simulations (LES). Structured meshes are generated as far as possible. Simulations are compared with an experiment. Results show that the grid and vanes have a combined effect: grid accelerates the flow whereas the vanes contribute to the swirl structures. Spectral analysis of the simulations illustrate vortex shedding phenomenon in the wake of spacer grids. This initial study opens up interesting perspectives towards improving the modeling strategy and understanding the complex phenomenon inside a PWR core. (C) 2017 Elsevier B.V. All rights reserved.
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. Comparative study of the contribution of various PWR spacer grid components to hydrodynamic and wall pressure characteristics. Nuclear Engineering and Design, Elsevier, 2017, 317, pp.22 - 43. ⟨10.1016/j.nucengdes.2017.03.011⟩. ⟨hal-01590274⟩
Richard Saurel, Ashwin Chinnayya, Quentin Carmouze. Modelling compressible dense and dilute two-phase flows. Physics of Fluids, American Institute of Physics, 2017, 29 (6), pp.063301. ⟨10.1063/1.4985289⟩. ⟨hal-01678274⟩ Plus de détails...
Many two-phase flow situations, from engineering science to astrophysics, deal with transition from dense (high concentration of the condensed phase) to dilute concentration (low concentration of the same phase), covering the entire range of volume fractions. Some models are now well accepted at the two limits, but none are able to cover accurately the entire range, in particular regarding waves propagation. In the present work, an alternative to the Baer and Nunziato (BN) model [Baer, M. R. and Nunziato, J. W., “A two-phase mixture theory for the deflagration-to-detonation transition (DDT) in reactive granular materials,” Int. J. Multiphase Flow 12(6), 861 (1986)], initially designed for dense flows, is built. The corresponding model is hyperbolic and thermodynamically consistent. Contrarily to the BN model that involves 6 wave speeds, the new formulation involves 4 waves only, in agreement with the Marble model [Marble, F. E., “Dynamics of a gas containing small solid particles,” Combustion and Propulsion (5th AGARD Colloquium) (Pergamon Press, 1963), Vol. 175] based on pressureless Euler equations for the dispersed phase, a well-accepted model for low particle volume concentrations. In the new model, the presence of pressure in the momentum equation of the particles and consideration of volume fractions in the two phases render the model valid for large particle concentrations. A symmetric version of the new model is derived as well for liquids containing gas bubbles. This model version involves 4 characteristic wave speeds as well, but with different velocities. Last, the two sub-models with 4 waves are combined in a unique formulation, valid for the full range of volume fractions. It involves the same 6 wave speeds as the BN model, but at a given point of space, 4 waves only emerge, depending on the local volume fractions. The non-linear pressure waves propagate only in the phase with dominant volume fraction. The new model is tested numerically on various test problems ranging from separated phases in a shock tube to shock–particle cloud interaction. Its predictions are compared to BN and Marble models as well as against experimental data showing clear improvements.
Richard Saurel, Ashwin Chinnayya, Quentin Carmouze. Modelling compressible dense and dilute two-phase flows. Physics of Fluids, American Institute of Physics, 2017, 29 (6), pp.063301. ⟨10.1063/1.4985289⟩. ⟨hal-01678274⟩
J Gubspun, C De Loubens, R Trozzo, Johnny Deschamps, M Georgelin, et al.. Perturbations of the flow induced by a microcapsule in a capillary tube. Fluid Dynamics Research, IOP Publishing, 2017, 49 (3), ⟨10.1088/1873-7005/aa6270⟩. ⟨hal-01590334⟩ Plus de détails...
Soft microcapsules moving in a cylindrical capillary deform from quasi-spherical shapes to elongated shapes with an inversion of curvature at the rear. We investigated the perturbation of the flow by particle tracking velocimetry around deformed microcapsules in confined flow. These experiments are completed by numerical simulations. Microcapsules are made of a thin membrane of polymerized human albumin and their shear elastic moduli are previously characterized in a cross flow chamber. Firstly, the velocity of the microcapsule can be calculated by theoretical predictions for rigid spheres, even for large deformations as 'parachute- like' shapes, if a relevant definition of the ratio of confinement is chosen. Secondly, at the rear and the front of the microcapsule, the existence of multiple recirculation regions is governed by the local curvature of the membrane. The amplitudes of these perturbations increase with the microcapsule deformation, whereas their axial extents are comparable to the radius of the capillary whatever the confinement and the capillary number. We conclude that whereas the motion of microcapsules in confined flow has quantitative similitudes with rigid spheres in terms of velocity and axial extent of the perturbation, their presence induces variations in the flow field that are related to the local deformation of the membrane as in droplets.
J Gubspun, C De Loubens, R Trozzo, Johnny Deschamps, M Georgelin, et al.. Perturbations of the flow induced by a microcapsule in a capillary tube. Fluid Dynamics Research, IOP Publishing, 2017, 49 (3), ⟨10.1088/1873-7005/aa6270⟩. ⟨hal-01590334⟩
François Joseph Chatelon, Jacques Henri Balbi, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli. A convective model for laboratory fires with well-ordered vertically-oriented fuel beds. Fire Safety Journal, Elsevier, 2017, 90, pp.54 - 61. ⟨10.1016/j.firesaf.2017.04.022⟩. ⟨hal-01590266⟩ Plus de détails...
Several studies in the literature explore the connection between rate of spread (ROS) and wind in wildland fires. These studies show very different positions about the role of radiation and convection as heat transfer mechanisms. In the case when the fuel bed is well-ordered and vertically-oriented, there seems to be a consensus leading to suggest that convective heating is the dominant heat transfer mode in that case. The purpose of this work is to propose a convective semi-physical model for the behaviour of the rate of spread in wind, when the fuel bed is vertically-oriented. Due to a specific fuel bed arrangement, flame radiation -i.e. radiation from the part of the flame above the vegetal stratum is neglected. Only horizontal radiation from the fuel burning particles area and convective heating are taken into account. Convective heat transfer is assumed to be the primary heat transfer mechanism. The proposed model is confronted to 172 laboratory fires with a wide range of fuel characteristics. The predicted results are also compared with two simplified models from the literature. Statistical tools are used to check the agreement between the predicted ROS and the observed one where a strong agreement is generally observed, irrespective of fuel bed characteristics.
François Joseph Chatelon, Jacques Henri Balbi, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli. A convective model for laboratory fires with well-ordered vertically-oriented fuel beds. Fire Safety Journal, Elsevier, 2017, 90, pp.54 - 61. ⟨10.1016/j.firesaf.2017.04.022⟩. ⟨hal-01590266⟩
Jonathan Gubspun, Marc Georgelin, Julien Deschamps, Marc Leonetti, Clément de Loubens, et al.. Perturbations of the flow induced by a microcapsule in a capillary tube. Fluid Dynamics Research, IOP Publishing, 2017, 49 (3), pp.035501. ⟨hal-02020111⟩ Plus de détails...
Soft microcapsules moving in a cylindrical capillary deform from quasi-spherical shapes to elongated shapes with an inversion of curvature at the rear. We investigated the perturbation of the flow by particle tracking velocimetry around deformed microcapsules in confined flow. These experiments are completed by numerical simulations. Microcapsules are made of a thin membrane of polymerized human albumin and their shear elastic moduli are previously characterized in a cross flow chamber. Firstly, the velocity of the microcapsule can be calculated by theoretical predictions for rigid spheres, even for large deformations as 'parachute-like' shapes, if a relevant definition of the ratio of confinement is chosen. Secondly, at the rear and the front of the microcapsule, the existence of multiple recirculation regions is governed by the local curvature of the membrane. The amplitudes of these perturbations increase with the microcapsule deformation, whereas their axial extents are comparable to the radius of the capillary whatever the confinement and the capillary number. We conclude that whereas the motion of microcapsules in confined flow has quantitative similitudes with rigid spheres in term of velocity and axial extent of the perturbation, their presence induces variations in the flow field that are related to the local deformation of the membrane as in droplets.
Jonathan Gubspun, Marc Georgelin, Julien Deschamps, Marc Leonetti, Clément de Loubens, et al.. Perturbations of the flow induced by a microcapsule in a capillary tube. Fluid Dynamics Research, IOP Publishing, 2017, 49 (3), pp.035501. ⟨hal-02020111⟩
S. Bodjona, E. Videcoq, Richard Saurel, A. Chinnayya, A.M. Benselama, et al.. Transient simulation of a two-phase loop thermosyphon with a model out of thermodynamic equilibrium. International Journal of Heat and Mass Transfer, Elsevier, 2017, 108, pp.2321 - 2332. ⟨10.1016/j.ijheatmasstransfer.2017.01.061⟩. ⟨hal-01678307⟩ Plus de détails...
Numerical investigation of two-phase loop thermosyphon (2PLT) in steady and transient states is addressed. A one-dimensional two-phase flow model describing a liquid-gas mixture in both mechanical and thermal equilibrium but out of thermodynamic equilibrium is developed. The model considers subcooled liquid and over heated vapor as well as phase transition (evaporation and condensation). The flow model is solved with a specific hyperbolic solver based on Godunov method and Harten-Lax-van Leer-Contact (HLLC) Riemann solver. A parametric study on the thermal power at the evaporator is performed in steady and transient states, the aim being to determine the effects of thermal power increase at the evaporator on the loop behavior. The comparison between Goodwin and Stiffened Gas (SG) equation of state (EOS) models shows fair agreement for latent heat of vaporization, specific volume and enthalpy for both liquid and vapor phases. Simulation of four test cases, corresponding to different evaporator thermal loads, is also carried out in transient state showing that loop response is correctly reproduced by this numerical approach, novel in the context of thermosyphon loops.
S. Bodjona, E. Videcoq, Richard Saurel, A. Chinnayya, A.M. Benselama, et al.. Transient simulation of a two-phase loop thermosyphon with a model out of thermodynamic equilibrium. International Journal of Heat and Mass Transfer, Elsevier, 2017, 108, pp.2321 - 2332. ⟨10.1016/j.ijheatmasstransfer.2017.01.061⟩. ⟨hal-01678307⟩
Journal: International Journal of Heat and Mass Transfer
C. Pantano, Richard Saurel, T. Schmitt. An oscillation free shock-capturing method for compressible van der Waals supercritical fluid flows. Journal of Computational Physics, Elsevier, 2017, 335, pp.780 - 811. ⟨10.1016/j.jcp.2017.01.057⟩. ⟨hal-01678279⟩ Plus de détails...
Numerical solutions of the Euler equations using real gas equations of state (EOS) often exhibit serious inaccuracies. The focus here is the van der Waals EOS and its variants (often used in supercritical fluid computations). The problems are not related to a lack of convexity of the EOS since the EOS are considered in their domain of convexity at any mesh point and at any time. The difficulties appear as soon as a density discontinuity is present with the rest of the fluid in mechanical equilibrium and typically result in spurious pressure and velocity oscillations. This is reminiscent of well-known pressure oscillations occurring with ideal gas mixtures when a mass fraction discontinuity is present, which can be interpreted as a discontinuity in the EOS parameters. We are concerned with pressure oscillations that appear just for a single fluid each time a density discontinuity is present. The combination of density in a nonlinear fashion in the EOS with diffusion by the numerical method results in violation of mechanical equilibrium conditions which are not easy to eliminate, even under grid refinement. A cure to this problem is developed in the present paper for the van der Waals EOS based on previous ideas. A special extra field and its corresponding evolution equation is added to the flow model. This new field separates the evolution of the nonlinear part of the density in the EOS and produce oscillation free solutions. The extra equation being nonconservative the behavior of two established numerical schemes on shocks computation is studied and compared to exact reference solutions that are available in the present context. The analysis shows that shock conditions of the nonconservative equation have important consequence on the results. Last, multidimensional computations of a supercritical gas jet is performed to illustrate the benefits of the present method, compared to conventional flow solvers.
C. Pantano, Richard Saurel, T. Schmitt. An oscillation free shock-capturing method for compressible van der Waals supercritical fluid flows. Journal of Computational Physics, Elsevier, 2017, 335, pp.780 - 811. ⟨10.1016/j.jcp.2017.01.057⟩. ⟨hal-01678279⟩
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⟩
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Darrieus–Landau instability of premixed flames enhanced by fuel droplets. Combustion Theory and Modelling, Taylor & Francis, 2017, 21 (4), pp.630 - 645. ⟨10.1080/13647830.2017.1279756⟩. ⟨hal-01678255⟩ Plus de détails...
Recent experiments on spray flames propagating in a Wilson cloud chamber have established that spray flames are much more sensitive to wrinkles or corrugations than single-phase flames. To propose certain elements of explanation, we numerically study the Darrieus–Landau (or hydrodynamic) instability (DL-instability) developing in premixtures that contain an array of fuel droplets. Two approaches are compared: numerical simulation starting from the general conservation laws in reactive media, and the numerical computation of Sivashinsky-type model equations for DL-instability. Both approaches provide us with results in deep agreement. It is first shown that the presence of droplets in fuel–air premixtures induces initial perturbations which are large enough to trigger the DL-instability. Second, the droplets are responsible for additional wrinkles when the DL-instability is developed. The latter wrinkles are of length scales shorter than those of the DL-instability, in such a way that the DL-unstable spray flames have a larger front surface and therefore propagate faster than the single-phase ones when subjected to the same instability
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Darrieus–Landau instability of premixed flames enhanced by fuel droplets. Combustion Theory and Modelling, Taylor & Francis, 2017, 21 (4), pp.630 - 645. ⟨10.1080/13647830.2017.1279756⟩. ⟨hal-01678255⟩
Spray flames are known to exhibit amazing features in comparison with single-phase flames. The weightless situation offers the conditions in which the spray characteristics can be well controlled before and during combustion. The article reports on a joint experimental/numerical work that concerns ethanol/air spray flames observed in a spherical chamber using the condensation technique of expansion cooling (based on the Wilson cloud chamber principle), under microgravity. We describe the experimental setup and give details on the creation of a homogeneous and nearly monosized aerosol. Different optical diagnostics are employed successfully to measure the relevant parameters of two-phase combustion. A classical shadowgraphy system is used to track the flame speed propagation and allow us to observe the flame front instability. The complete characterization of the aerosol is performed with a laser diffraction particle size analyser by measuring the droplet diameter and the droplet density number, just before ignition. A laser tomography device allows us to measure the temporal evolution of the droplet displacement during flame propagation, as well as to identify the presence of droplets in the burnt gases. The numerical modelling is briefly recalled. In particular, spray-flame propagation is schematized by the combustion spread in a 2-D lattice of fuel droplets surrounded by an initial gaseous mixture of fuel vapour and air. In its spherical expansion, the spray flame presents a corrugated front pattern, while the equivalent single-phase flame does not. From a numerical point of view, the same phenomena of wrinkles are also observed in the simulations. The front pattern pointed out by the numerical approach is identified as of Darrieus–Landau (DL) type. The droplets are found to trigger the instability. Then, we quantitatively compare experimental data with numerical predictions on spray-flame speed. The experimental results show that the spray-flame speed is of the same order of magnitude as that of the single-phase premixed flame. On the other hand, the numerical results exhibit the role played by the droplet radius in spray-flame propagation, and retrieve the experiments only when the droplets are small enough and when the Darrieus–Landau instability is triggered. A final discussion is developed to interpret the various patterns experimentally observed for the spray-flame front.
Romain Thimothée, Christian Chauveau, Fabien Halter, Colette Nicoli, Pierre Haldenwang, et al.. Microgravity experiments and numerical studies on ethanol/air spray flames. Comptes Rendus Mécanique, Elsevier Masson, 2017, 345 (2), pp.99 - 116. ⟨10.1016/j.crme.2016.10.013⟩. ⟨hal-01441677⟩
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small−scale waves within the Stewartson layers of the thermally driven rotating annulus
. Journal of Fluid Mechanics, Cambridge University Press (CUP), In press. ⟨hal-01670784⟩ Plus de détails...
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small−scale waves within the Stewartson layers of the thermally driven rotating annulus
. Journal of Fluid Mechanics, Cambridge University Press (CUP), In press. ⟨hal-01670784⟩
H Berjamin, Bruno Lombard, Guillaume Chiavassa, N Favrie. Analytical solution to the 1D nonlinear elastodynamics with general constitutive laws. Wave Motion, Elsevier, 2017, 74, pp.35-55. ⟨10.1016/j.wavemoti.2017.06.006⟩. ⟨hal-01350116⟩ Plus de détails...
Under the hypothesis of small deformations, the equations of 1D elastodynamics write as a 2 × 2 hyperbolic system of conservation laws. Here, we study the Riemann problem for convex and nonconvex constitutive laws. In the convex case, the solution can include shock waves or rarefaction waves. In the nonconvex case, compound waves must also be considered. In both convex and nonconvex cases, a new existence criterion for the initial velocity jump is obtained. Also, admissibility regions are determined. Lastly, analytical solutions are completely detailed for various constitutive laws (hyperbola, tanh and polynomial), and reference test cases are proposed.
H Berjamin, Bruno Lombard, Guillaume Chiavassa, N Favrie. Analytical solution to the 1D nonlinear elastodynamics with general constitutive laws. Wave Motion, Elsevier, 2017, 74, pp.35-55. ⟨10.1016/j.wavemoti.2017.06.006⟩. ⟨hal-01350116⟩
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple and fast phase transition relaxation solver for compressible multicomponent two-phase flows. Computers and Fluids, Elsevier, 2017, 150, pp.31 - 45. ⟨10.1016/j.compfluid.2017.03.022⟩. ⟨hal-01502389⟩ Plus de détails...
The present paper aims at building a fast and accurate phase transition solver dedicated to unsteady multiphase flow computations. In a previous contribution (Chiapolino et al. 2017), such a solver was successfully developed to compute thermodynamic equilibrium between a liquid phase and its corresponding vapor phase. The present work extends the solver's range of application by considering a multicomponent gas phase instead of pure vapor, a necessary improvement in most practical applications. The solver proves easy to implement compared to common iterative procedures, and allows systematic CPU savings over 50%, at no cost in terms of accuracy. It is validated against solutions based on an accurate but expensive iterative solver. Its capability to deal with cavitating, evaporating and condensing two-phase flows is highlighted on severe test problems both 1D and 2D.
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple and fast phase transition relaxation solver for compressible multicomponent two-phase flows. Computers and Fluids, Elsevier, 2017, 150, pp.31 - 45. ⟨10.1016/j.compfluid.2017.03.022⟩. ⟨hal-01502389⟩
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple phase transition relaxation solver for liquid-vapor flows. International Journal for Numerical Methods in Fluids, Wiley, 2017, 83 (7), pp.583-605. ⟨10.1002/fld.4282⟩. ⟨hal-01359203⟩ Plus de détails...
Determining liquid-vapor phase equilibrium is often required in multiphase flow computations. Existing equilibrium solvers are either accurate but computationally expensive, or cheap but inaccurate. The present paper aims at building a fast and accurate specific phase equilibrium solver, specifically devoted to unsteady multiphase flow computations. Moreover, the solver is efficient at phase diagram bounds, where non-equilibrium pure liquid and pure gas are present. It is systematically validated against solutions based on an accurate (but expensive) solver. Its capability to deal with cavitating, evaporating and condensing two-phase flows is highlighted on severe test problems both 1D and 2D.
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple phase transition relaxation solver for liquid-vapor flows. International Journal for Numerical Methods in Fluids, Wiley, 2017, 83 (7), pp.583-605. ⟨10.1002/fld.4282⟩. ⟨hal-01359203⟩
Journal: International Journal for Numerical Methods in Fluids
Rachel Aganetti, Aymeric Lamorlette, G.R. Thorpe. The relationship between external and internal flow in a porous body using the penalisation method. International Journal of Heat and Fluid Flow, Elsevier, 2017, 66 (66), pp.185 - 196. ⟨10.1016/j.ijheatfluidflow.2017.06.003⟩. ⟨hal-01547073⟩ Plus de détails...
Stockpiles of organic porous materials such as biosolids, coal, compost and woodchips are susceptible to spontaneous combustion. Flow fields within such materials are induced by buoyant forces and external agents such as the wind. However, the external forces may vary on a time scale of seconds, whereas the heat, mass and momentum processes within the porous medium may occur over timescales days or months. It would be computationally prohibitive to resolve all of the timescales, hence in this paper mean external forces are coupled to the flow field within stockpiles of biosolids by means of a penalisation method. It has been determined that four variables have a profound influence of the flow fields within porous media. These are the velocity of the wind, the permeability of the porous biosolids, the angle of repose of the medium and aspect ratio of the stockpile. Four distinct flow regimes within the stockpiles have been identified. A correlation has been developed to assist managers of stockpiles, which relates mean velocities within the four flow regimes with a Darcy and Reynolds number, the aspect ratio and angle of repose. The correlation is accurate for two of the four flow regions identified, but the error in predicting the two remaining regions is relatively large. However, this error is expected to have minimal impact on estimating the time for spontaneous combustion to occur.
Rachel Aganetti, Aymeric Lamorlette, G.R. Thorpe. The relationship between external and internal flow in a porous body using the penalisation method. International Journal of Heat and Fluid Flow, Elsevier, 2017, 66 (66), pp.185 - 196. ⟨10.1016/j.ijheatfluidflow.2017.06.003⟩. ⟨hal-01547073⟩
Journal: International Journal of Heat and Fluid Flow
H Berjamin, N Favrie, B Lombard, G Chiavassa. Nonlinear waves in solids with slow dynamics: an internal-variable model. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Royal Society, The, 2017, 473 (2201), pp.20170024. ⟨10.1098/rspa.2017.0024⟩. ⟨hal-01517335⟩ Plus de détails...
In heterogeneous solids such as rocks and concrete, the speed of sound diminishes with the strain amplitude of a dynamic loading (softening). This decrease known as " slow dynamics " occurs at time scales larger than the period of the forcing. Also, hysteresis is observed in the steady-state response. The phenomenological model by Vakhnenko et al. is based on a variable that describes the softening of the material [Phys. Rev. E 70-1, 2004]. However, this model is 1D and it is not thermodynamically admissible. In the present article, a 3D model is derived in the framework of the finite strain theory. An internal variable that describes the softening of the material is introduced, as well as an expression of the specific internal energy. A mechanical constitu-tive law is deduced from the Clausius-Duhem inequality. Moreover, a family of evolution equations for the internal variable is proposed. Here, an evolution equation with one relaxation time is chosen. By construction, this new model of continuum is thermodynamically admissible and dissipative (inelas-tic). In the case of small uniaxial deformations, it is shown analytically that the model reproduces qualitatively the main features of real experiments.
H Berjamin, N Favrie, B Lombard, G Chiavassa. Nonlinear waves in solids with slow dynamics: an internal-variable model. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Royal Society, The, 2017, 473 (2201), pp.20170024. ⟨10.1098/rspa.2017.0024⟩. ⟨hal-01517335⟩
Journal: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Richard Saurel, Olivier Le Métayer, Pierre Boivin. From Cavitating to Boiling Flows. d'Agostino L., Salvetti M.; CISM International Centre for Mechanical Sciences (Courses and Lectures). Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines , 575, Springer pp.259-282 2017, 978-3-319-49717-4. ⟨hal-01678361⟩ Plus de détails...
A flow model is derived for the numerical simulation of interfacial flows with phase transition. The model arises from the classical multi-component Euler equations, but is associated to a non-classical thermodynamic closure: each phase is compressible and evolves in its own subvolume, with phases sharing common pressure, velocity and temperature, leading to non-trivial thermodynamic relations for the mixture. Phase transition is made possible through the introduction of Gibbs free energy relaxation terms in the equations. Capillary effects and heat conduction—essential in boiling flows—are introduced as well. The resulting multi-phase flow model is hyperbolic, valid for arbitrary density jumps at interfaces as well as arbitrary flow speeds. Its capabilities are illustrated successively through examples of nozzle induced cavitation and heated wall induced boiling.
Richard Saurel, Olivier Le Métayer, Pierre Boivin. From Cavitating to Boiling Flows. d'Agostino L., Salvetti M.; CISM International Centre for Mechanical Sciences (Courses and Lectures). Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines , 575, Springer pp.259-282 2017, 978-3-319-49717-4. ⟨hal-01678361⟩
Evelyne Neau, Isabelle Raspo, Joan Escandell. The NRTL-PRA group contribution EoS for the simultaneous prediction of LLE, VLE and hE of hydrocarbon mixtures with associating compounds. Fluid Phase Equilibria, Elsevier, 2016, 427, pp.126-142. ⟨10.1016/j.fluid.2016.06.035⟩. ⟨hal-01369874⟩ Plus de détails...
The goal of this study is to propose a modification of the NRTL-PR EoS for the prediction of phase equilibria and excess enthalpies in mixtures containing methanol with hydrocarbons; indeed, with these systems, the original equation is confronted to many difficulties arising from the simultaneous prediction of liquid-liquid equilibria together with vapor-liquid and enthalpy data. For this purpose, an additional term is included in the EoS excess Gibbs energy, , of the Peng-Robinson equation to account for the self-association of methanol. The resulting NRTL-PRA EoS is successfully used for the prediction of both liquid-liquid and vapor-liquid equilibria, as well as excess enthalpies, in mixtures of methanol with hydrocarbons, light gases and associating compounds. Results are comparable to those obtained with other predictive EoS (VTPR and SAFT), but with the main advantage to predict all thermodynamic properties with a simple cubic equation.
Evelyne Neau, Isabelle Raspo, Joan Escandell. The NRTL-PRA group contribution EoS for the simultaneous prediction of LLE, VLE and hE of hydrocarbon mixtures with associating compounds. Fluid Phase Equilibria, Elsevier, 2016, 427, pp.126-142. ⟨10.1016/j.fluid.2016.06.035⟩. ⟨hal-01369874⟩
Manel Wannassi, Isabelle Raspo. Numerical study of non-isothermal adsorption of Naphthalene in supercritical CO2: behavior near critical point. Journal of Supercritical Fluids, Elsevier, 2016, 117, pp.203-218. ⟨10.1016/j.supflu.2016.06.020⟩. ⟨hal-01369830⟩ Plus de détails...
In this study, adsorption in a model binary mixture is investigated near the critical point in a side-heated cavity. The diverging behavior of the equilibrium constant and the Piston effect are taken into account and their influence on the adsorption process is pointed to. The modeling is based on numerical integration of the differential equations, considering the Navier-Stokes equations coupled with the energy and mass diffusion balances. By means of this model, the temperature, density and adsorbed concentration profiles are drawn at different times. Some fundamental concepts about the system’s response to the heating are illustrated. The results reveal that the adsorption process is influenced by the combined effect of several parameters, such as the gravity and the proximity to the critical point. In particular, the adsorbed amount exhibits a reversed dependency on the wall heating very close to the critical point, which confirms the complexity of such a process in binary systems near critical conditions.
Manel Wannassi, Isabelle Raspo. Numerical study of non-isothermal adsorption of Naphthalene in supercritical CO2: behavior near critical point. Journal of Supercritical Fluids, Elsevier, 2016, 117, pp.203-218. ⟨10.1016/j.supflu.2016.06.020⟩. ⟨hal-01369830⟩
Romain Oguic, Sébastien Poncet, Stéphane Viazzo. High-order direct numerical simulations of a turbulent round impinging jet onto a rotating heated disk in a highly confined cavity. International Journal of Heat and Fluid Flow, Elsevier, 2016, 61 (B), pp.366-378. ⟨10.1016/j.ijheatfluidflow.2016.05.013⟩. ⟨hal-01461786⟩ Plus de détails...
The present work reports Direct Numerical Simulations (DNS) of an impinging round jet onto a rotating heated disk in a confined rotor-stator cavity. The geometrical characteristics of the system correspond to the experimental set-up developed by u. Pelle and S. Harmand. Heat transfer study in a rotor-stator system air-gap with an axial inflow. Applied Thermal Engineering, 29:1532-1543, 2009.]. The aspect ratio of the cavity G = h/R-d between the interdisk spacing h and the rotor radius R-d is fixed to 0.02 corresponding to a narrow-gap cavity. The axial Reynolds number Red based on the jet characteristics is also fixed to Re-j = 5300, while the rotational Reynolds number Re-Omega may vary to preserve the swirl parameter N proportional to Re(Omega)dRe(j) (0 <= N <= 2.47) between the present simulations and the experimental data of [J. Pelle and S. Harmand. Heat transfer study in a rotor-stator system air-gap with an axial inflow. Applied Thermal Engineering, 29:1532-1543, 2009.] and [T. D. Nguyen, J. Pelle, S. Harmand, and S. Poncet. PIV measurements of an air jet impinging on an open rotor-stator system. Experiments in Fluids, 53:401-412, 2012.] for comparisons. The results are discussed in terms of radial distributions of the mean velocity components and corresponding Reynolds stress tensor components. The swirl parameter does not modify the size of the recirculation bubble developed along the stator close to the pipe exit. For N >= 1.237, centrifugal effects at the rotor periphery are balanced by a centripetal flow along the stator. Some spiral patterns develop then in the stator boundary layer corresponding to the SRIII instability of [L. Schouveiler, P. Le Gal, and M. P. Chauve. Instabilities of the flow between a rotating and a stationary disk. Journal of Fluid Mechanics, 443:329-350, 2001.] in an enclosed cavity. The numerical results are found to agree particularly well with the experimental data in terms of the distribution of the local Nusselt number along the rotor. Finally, a correlation for its averaged value is proposed according to the swirl parameter. (C) 2016 Elsevier Inc. All rights reserved.
Romain Oguic, Sébastien Poncet, Stéphane Viazzo. High-order direct numerical simulations of a turbulent round impinging jet onto a rotating heated disk in a highly confined cavity. International Journal of Heat and Fluid Flow, Elsevier, 2016, 61 (B), pp.366-378. ⟨10.1016/j.ijheatfluidflow.2016.05.013⟩. ⟨hal-01461786⟩
Journal: International Journal of Heat and Fluid Flow
Salim Bounoua, Séverine Tomas, Jérôme Labille, Bruno Molle, Jacques Granier, et al.. Understanding physical clogging in drip irrigation: in situ, in-lab and numerical approaches. Irrigation Science, Springer Verlag, 2016, 34 (4), pp.327-342. ⟨10.1007/s00271-016-0506-8⟩. ⟨hal-01519534⟩ Plus de détails...
Dripper clogging is a major drawback of microirrigation systems that must be addressed to improve their efficiency and durability. Particle-induced clogging is first studied in situ. The experiments consist in observing in real conditions the behavior of a series of drippers fitted on an agricultural plot in the south of France. The plot is supplied from a canal with Durance River water. The latter is loaded with sediments that gradually clog drippers and filters. Water analysis reveal that physicochemical clogging prevails over biological clogging. This characterization helps in setting in-lab experiment protocol. Indeed, besides field observation of clogging, laboratory analyses of both the irrigation water and the clogging material are performed with reactive and inert clay: smectite and an illite-calcite mix. A surprising tendency is observed: Salt concentration in smectite seeded water decreases the clogging, whereas it increases agglomerate size. Computational fluid dynamic simulations are carried out to investigate the impact of particles on flow behavior. Results demonstrate that clay particles interacting with the flow govern the complex structure of the fluid velocity fields inside the dripper labyrinth channel.
Salim Bounoua, Séverine Tomas, Jérôme Labille, Bruno Molle, Jacques Granier, et al.. Understanding physical clogging in drip irrigation: in situ, in-lab and numerical approaches. Irrigation Science, Springer Verlag, 2016, 34 (4), pp.327-342. ⟨10.1007/s00271-016-0506-8⟩. ⟨hal-01519534⟩
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⟩
Richard Saurel, Pierre Boivin, Olivier Le Métayer. A general formulation for cavitating, boiling and evaporating flows. Computers and Fluids, Elsevier, 2016, 128, pp.53-64. ⟨10.1016/j.compfluid.2016.01.004⟩. ⟨hal-01277179⟩ Plus de détails...
A flow model is derived for the numerical simulation of multi-phase flows with phase transition. The model arises from the classical multi-component Euler equations, but is associated to a non-classical thermodynamic closure: each phase is compressible and evolves in its own subvolume, with phases sharing common pressure, velocity and temperature, leading to non-trivial thermodynamic relations for the mixture. Phase transition is made possible through the introduction of Gibbs free energy relaxation terms in the equations. Capillary effects and heat conduction – essential in boiling flows – are introduced as well. The resulting multi-phase flow model is hyperbolic, valid for arbitrary density jumps at interfaces as well as arbitrary flow speeds. Its capabilities are illustrated successively through examples of nozzle induced cavitation, a high-speed evaporating liquid jet, and heated wall induced boiling.
Richard Saurel, Pierre Boivin, Olivier Le Métayer. A general formulation for cavitating, boiling and evaporating flows. Computers and Fluids, Elsevier, 2016, 128, pp.53-64. ⟨10.1016/j.compfluid.2016.01.004⟩. ⟨hal-01277179⟩
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Spray-Flame Dynamics in a Rich Droplet Array. Flow, Turbulence and Combustion, Springer Verlag (Germany), 2016, 96 (2), pp.377-389. ⟨10.1007/s10494-015-9675-4⟩. ⟨hal-01282878⟩ Plus de détails...
In a recent numerical paper (Nicoli et al. Combust. Sci. Technol. vol. 186, pp. 103-119; 2014) [1], a model of isobaric flame propagation in lean sprays has been proposed. The initial state of the monodisperse mists was schematized by a system of individual alkane droplets initially located at the nodes of a face-centered 2D-lattice, surrounded by a saturated mixture of alkane and air. In the present study, the previous model is complemented with an original chemical scheme that allows us to study the combustion of rich alkane/air mixtures.
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Spray-Flame Dynamics in a Rich Droplet Array. Flow, Turbulence and Combustion, Springer Verlag (Germany), 2016, 96 (2), pp.377-389. ⟨10.1007/s10494-015-9675-4⟩. ⟨hal-01282878⟩
Rachael Aganetti, Aymeric Lamorlette, Guilbert Emilie, Dominique Morvan, G.R. Thorpe. Advection and the self-heating of organic porous media. International Journal of Heat and Mass Transfer, Elsevier, 2016, ⟨10.1016/j.ijheatmasstransfer.2015.11.023⟩. ⟨hal-01345737⟩ Plus de détails...
Self-heating is commonly observed when organic materials such as biosolids, coal, food grains and compost are stockpiled. A convection–diffusion model is presented that accounts for the roles of advection and the transport of oxygen in the self-heating process, as well as the development of an empirical correlation between dimensionless Darcy number, Frank–Kamenetskii parameter and pile aspect ratio, to predict the critical permeability above which thermal runaway can be avoided. It is apparent that the permeability of the stockpile determines the likelihood of the thermal runaway. However, the solids that form a stockpile are poly-disperse and it is essential to determine an effective permeability. This has been achieved using experimental data on biosolids obtained from a wastewater treatment plant in Australia. With this method the model is used to demonstrate how the permeability of a stockpile might be adjusted to reduce the incidence of thermal runaway.
Rachael Aganetti, Aymeric Lamorlette, Guilbert Emilie, Dominique Morvan, G.R. Thorpe. Advection and the self-heating of organic porous media. International Journal of Heat and Mass Transfer, Elsevier, 2016, ⟨10.1016/j.ijheatmasstransfer.2015.11.023⟩. ⟨hal-01345737⟩
Journal: International Journal of Heat and Mass Transfer
Mohamad El Houssami, J.C. Thomas, Aymeric Lamorlette, Dominique Morvan, M. Chaos, et al.. Experimental and numerical studies characterizing the burning dynamics of wildland fuels. Combustion and Flame, Elsevier, 2016, 168, pp.113-126. ⟨10.1016/j.combustflame.2016.04.004⟩. ⟨hal-01345741⟩ Plus de détails...
A method to accurately understand the processes controlling the burning behavior of porous wildland fuels is presented using numerical simulations and laboratory experiments. A multiphase approach has been implemented in OpenFOAM, which is based on the FireFOAM solver for large eddy simulations (LES). Conservation equations are averaged in a control volume containing a gas and a solid phase. Drying, pyrolysis, and char oxidation are described by interaction between the two phases. Numerical simulations are compared to laboratory experiments carried out with porous pine needle beds in the FM Global Fire Propagation Apparatus (FPA). These experiments are used to support the use and the development of submodels that represent heat transfer, pyrolysis, gas-phase combustion, and smoldering processes. The model is tested for different bulk densities, two distinct species and two different radiative heat fluxes used to heat up the samples. It has been possible to reproduce mass loss rates, heat release rates, and temperatures that agree with experimental observations, and to highlight the current limitations of the model.
Mohamad El Houssami, J.C. Thomas, Aymeric Lamorlette, Dominique Morvan, M. Chaos, et al.. Experimental and numerical studies characterizing the burning dynamics of wildland fuels. Combustion and Flame, Elsevier, 2016, 168, pp.113-126. ⟨10.1016/j.combustflame.2016.04.004⟩. ⟨hal-01345741⟩
O Le Métayer, Richard Saurel. The Noble-Abel Stiffened-Gas equation of state. Physics of Fluids, American Institute of Physics, 2016, 28, pp.046102. ⟨10.1063/1.4945981⟩. ⟨hal-01305974⟩ Plus de détails...
Hyperbolic two-phase flow models have shown excellent ability for the resolution of a wide range of applications ranging from interfacial flows to fluid mixtures with several velocities. These models account for waves propagation (acoustic and convective) and consist in hy-perbolic systems of partial differential equations. In this context, each phase is compressible and needs an appropriate convex equation of state (EOS). The EOS must be simple enough for intensive computations as well as boundary conditions treatment. It must also be accurate , this being challenging with respect to simplicity. In the present approach, each fluid is governed by a novel EOS named 'Noble Abel Stiffened Gas' (NASG), this formulation being a significant improvement of the popular 'Stiffened Gas' (SG) EOS. It is a combination of the so-called 'Noble-Abel' and 'Stiffened Gas' equations of state that adds repulsive effects to the SG formulation. The determination of the various thermodynamic functions and associated coefficients is the aim of this article. We first use thermodynamic considerations to determine the different state functions such as the specific internal energy, enthalpy and entropy. Then we propose to determine the associated coefficients for a liquid in the presence of its vapor. The EOS parameters are determined from experimental saturation curves. Some examples of liquid-vapor fluids are examined and associated parameters are computed with the help of the present method. Comparisons between analytical and experimental saturation curves show very good agreement for wide ranges of temperature for both liquid and vapor.
O Le Métayer, Richard Saurel. The Noble-Abel Stiffened-Gas equation of state. Physics of Fluids, American Institute of Physics, 2016, 28, pp.046102. ⟨10.1063/1.4945981⟩. ⟨hal-01305974⟩
Damien Furfaro, Richard Saurel. Modeling droplet phase change in the presence of a multi-component gas mixture. Computational and Applied Mathematics, Springer Verlag, 2016, 272 (part.2), pp.518-541. ⟨10.1016/j.amc.2015.02.083⟩. ⟨hal-01278890⟩ Plus de détails...
Dispersed liquid droplet flows with evaporation and condensation in multi-component gas mixture made of vapor and other gas phase chemical species such as air occur in many engineering applications dealing with two-phase flows. However, existing models are essentially derived for vaporization occurring in sprays combustion. It means that the energy is transferred from a hot gas to the liquid to produce its phase change. This is thus a non-symmetric approach as in some situations the energy is already stored in the liquid phase and flashing occurs as a consequence of pressure drop. In the present paper a droplet mass transfer model is derived and is valid in any situation: evaporation, flashing and condensation. It accounts for: - coupled heat and mass diffusion in the gas phase, - thermodynamics of the multi-component gas mixture, - heat diffusion inside the liquid droplet, enabling consideration of both droplet heating and cooling. These effects are important in evaporating and flashing situations respectively. The resulting model consists in an algebraic non-linear system of three equations giving the interface temperature, the mass flow rate and vapor species concentration at the interface. These interfacial variables enable computation of the mass species, momentum and energy transfer rates appearing in volume averaged two-phase flow models. Computational examples are shown with this mass transfer model embedded in a compressible two-phase flow model of Baer and Nunziato (1986) type.
Damien Furfaro, Richard Saurel. Modeling droplet phase change in the presence of a multi-component gas mixture. Computational and Applied Mathematics, Springer Verlag, 2016, 272 (part.2), pp.518-541. ⟨10.1016/j.amc.2015.02.083⟩. ⟨hal-01278890⟩
Colette Nicoli, Bruno Denet, Pierre Haldenwang. Rich Spray-Flame Propagating through a 2D-Lattice of Alkane Droplets in Air. Combustion and Flame, Elsevier, 2015, 162 (12), pp.4598-4611. ⟨10.1016/j.combustflame.2015.09.018⟩. ⟨hal-01255816⟩ Plus de détails...
In a recent numerical paper (Nicoli et al. Combust. Sci. Technol. vol. 186, pp. 103-119; 2014) [1], a model of isobaric flame propagation in lean sprays has been proposed. The initial state of the monodisperse mists was schematized by a system of individual alkane droplets initially located at the nodes of a face-centered 2D-lattice, surrounded by a saturated mixture of alkane and air. In the present study, the previous model is complemented with an original chemical scheme that allows us to study the combustion of rich alkane/air mixtures.
Colette Nicoli, Bruno Denet, Pierre Haldenwang. Rich Spray-Flame Propagating through a 2D-Lattice of Alkane Droplets in Air. Combustion and Flame, Elsevier, 2015, 162 (12), pp.4598-4611. ⟨10.1016/j.combustflame.2015.09.018⟩. ⟨hal-01255816⟩
We present an efficient parallelized multidomain algorithm for solving the 3D Navier–Stokes equations in cylindrical geometries. The numerical method is based on fourth-order compact schemes in the two non-homogeneous directions and Fourier series expansion in the azimuthal direction. The temporal scheme is a second-order semi-implicit projection scheme leading to the solution of five Helmholtz/Poisson equations. To handle the singularity appearing at the axis in cylindrical coordinates, while being able to have a thinner or conversely a coarser mesh in this zone, parity conditions are imposed at r=0r=0 for each flow variable and azimuthal Fourier mode. To simulate flows in irregularly shaped cylindrical geometries and benefit from a hybrid OpenMP/MPI parallelization, an accurate perfectly free-divergence multidomain method based on the influence matrix technique is proposed. First, the accuracy of the present solver is checked by comparison with analytical solutions and the scalability is then evaluated. Simulations using the present code are then compared to reliable experimental and numerical results of the literature showing good quantitative agreements in the cases of the axisymmetric and 3D unsteady vortex breakdowns in a cylinder and turbulent pipe flow. Finally to show the capability of the algorithm to deal with more complex flows relevant of turbomachineries, the turbulent flow inside a simplified stage of High-Pressure compressor is considered.
Romain Oguic, Stéphane Viazzo, Sébastien Poncet. A parallelized multidomain compact solver for incompressible turbulent flows in cylindrical geometries. Journal of Computational Physics, Elsevier, 2015, 300, pp.710-731. ⟨10.1016/j.jcp.2015.08.003⟩. ⟨hal-01299082⟩
Anthony Randriamampianina, Emilia Crespo del Arco. Inertia–gravity waves in a liquid-filled, differentially heated, rotating annulus. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2015, 782, pp.144- 177. ⟨10.1017/jfm.2015.522⟩. ⟨hal-01230540⟩ Plus de détails...
Direct numerical simulations based on high-resolution pseudospectral methods are carried out for detailed investigation into the instabilities arising in a differentially heated, rotating annulus, the baroclinic cavity. Following previous works using air (Randriamampianina et al., J. Fluid Mech., vol. 561, 2006, pp. 359–389), a liquid defined by Prandtl number Pr=16 is considered in order to better understand, via the Prandtl number, the effects of fluid properties on the onset of gravity waves. The computations are particularly aimed at identifying and characterizing the spontaneously emitted small-scale fluctuations occurring simultaneously with the baroclinic waves. These features have been observed as soon as the baroclinic instability sets in. A three-term decomposition is introduced to isolate the fluctuation field from the large-scale baroclinic waves and the time-averaged mean flow. Even though these fluctuations are found to propagate as packets, they remain attached to the background baroclinic waves, locally triggering spatio-temporal chaos, a behaviour not observed with the air-filled cavity. The properties of these features are analysed and discussed in the context of linear theory. Based on the Richardson number criterion, the characteristics of the generation mechanism are consistent with a localized instability of the shear zonal flow, invoking resonant over-reflection.
Anthony Randriamampianina, Emilia Crespo del Arco. Inertia–gravity waves in a liquid-filled, differentially heated, rotating annulus. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2015, 782, pp.144- 177. ⟨10.1017/jfm.2015.522⟩. ⟨hal-01230540⟩
Guillaume Chiavassa, M.C. Martí, P. Mulet. Hybrid WENO schemes for polydisperse sedimentation models. International Journal of Computer Mathematics, Taylor & Francis, 2015, pp.1-17. ⟨10.1080/00207160.2015.1075985⟩. ⟨hal-01297719⟩ Plus de détails...
Polydisperse sedimentation models can be described by a strongly coupled system of conservation laws for the concentration of each species of solids. Typical solutions for the sedimentation model considered for batch settling in a column include stationary kinematic shocks separating layers of sediment of different composition. This phenomenon, known as segregation of species, is a specially demanding task for numerical simulation due to the need of accurate numerical simulations. Very high-order accurate solutions can be constructed by incorporating characteristic information, available due to the hyperbolicity analysis made in Donat and Mulet [A secular equation for the Jacobian matrix of certain multispecies kinematic flow models, Numer. Methods Partial Differential Equations 26 (2010), pp. 159–175.] But characteristic-based schemes, see Bürger et al. [On the implementation of WENO schemes for a class of polydisperse sedimentation models, J. Comput. Phys. 230 (2011), pp. 2322–2344], are very expensive in terms of computational time, since characteristic information is not readily available, and they are not really necessary in constant areas, where a less complex method can obtain similar results. With this idea in mind, in this paper we develop a hybrid finite difference WENO scheme that only uses the characteristic information of the Jacobian matrix of the system in those regions where singularities exist or are starting to develop, while it uses a component-wise approximation of the scheme in smooth regions. We perform some experiments showing the computational gains that can be achieved by this strategy.
Guillaume Chiavassa, M.C. Martí, P. Mulet. Hybrid WENO schemes for polydisperse sedimentation models. International Journal of Computer Mathematics, Taylor & Francis, 2015, pp.1-17. ⟨10.1080/00207160.2015.1075985⟩. ⟨hal-01297719⟩
Journal: International Journal of Computer Mathematics
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⟩