In this paper, we propose a high-order finite volume method for solving multicomponent fluid problems. Our method couples the quasi-conservative form with the reconstruction of conservative variables in a characterist...In this paper, we propose a high-order finite volume method for solving multicomponent fluid problems. Our method couples the quasi-conservative form with the reconstruction of conservative variables in a characteristic manner. The source term and numerical fluxes are carefully designed to maintain the pressure and velocity equilibrium for the interface-only problem and preserve the equilibrium of physical parameters in a single-component fluid. These ingredients enable our scheme to achieve both high-order accuracy in the smooth region and the high resolution in the discontinuity region of the solution. Extensive numerical tests are performed to verify the high resolution and accuracy of the scheme.展开更多
In this paper, a pseudopotential-based multiplerelaxation-time lattice Boltzmann model is proposed for multicomponent/multiphase flow systems. Unlike previous models in the literature, the present model not only enabl...In this paper, a pseudopotential-based multiplerelaxation-time lattice Boltzmann model is proposed for multicomponent/multiphase flow systems. Unlike previous models in the literature, the present model not only enables the study of multicomponent flows with different molecular weights, different viscosities and different Schmidt numbers, but also ensures that the distribution function of each component evolves on the same square lattice without invoking ad- ditional interpolations. Furthermore, the Chapman-Enskog analysis shows that the present model results in the correct hydrodynamic equations, and satisfies the indifferentiability principle. The numerical validation exercises further demonstrate that the favorable performance of the present model.展开更多
This article focuses on the development of a discontinuous Galerkin (DG) method for simulations of multicomponent and chemically reacting flows. Compared to aerodynamic flow applications, in which DG methods have been...This article focuses on the development of a discontinuous Galerkin (DG) method for simulations of multicomponent and chemically reacting flows. Compared to aerodynamic flow applications, in which DG methods have been successfully employed, DG simulations of chemically reacting flows introduce challenges that arise from flow unsteadiness, combustion, heat release, compressibility effects, shocks, and variations in thermodynamic properties. To address these challenges, algorithms are developed, including an entropy-bounded DG method, an entropy-residual shock indicator, and a new formulation of artificial viscosity. The performance and capabilities of the resulting DG method are demonstrated in several relevant applications, including shock/bubble interaction, turbulent combustion, and detonation. It is concluded that the developed DG method shows promising performance in application to multicomponent reacting flows. The paper concludes with a discussion of further research needs to enable the application of DG methods to more complex reacting flows.展开更多
This paper presents a pseudopotential lattice Boltzmann analysis to show the deficiency of previous pseudopotential models,i.e.,inconsistency between equilibrium velocity and mixture velocity.To rectify this problem,t...This paper presents a pseudopotential lattice Boltzmann analysis to show the deficiency of previous pseudopotential models,i.e.,inconsistency between equilibrium velocity and mixture velocity.To rectify this problem,there are two strategies:decoupling relaxation time and kinematic viscosity or introducing a system mixture relaxation time.Then,we constructed two modified models:a two-relaxationtime(TRT)scheme and a triple-relaxation-time(TriRT)scheme to decouple the relaxation time and kinematic viscosity.Meanwhile,inspired by the idea of a system mixture relaxation time,we developed three mixture models under different collision schemes,viz.mix-SRT,mix-TRT,and mix-TriRT models.Afterwards,we derived the advection-diffusion equation for the multicomponent system and derived the mutual diffusivity in a binarymixture.Finally,we conducted several numerical simulations to validate the analysis on these models.The numerical results show that these models can obtain smaller spurious currents than previous models and have a wider range for the accessible viscosity ratio with fourth-order isotropy.Compared to previous models,presentmodels avoid complex matrix operations and only fourth-order isotropy is required.The increased simplicity and higher computational efficiency of these models make them easy to apply to engineering and industrial applications.展开更多
In this paper,a gas kinetic scheme for the compressible multicomponent flows is presented by making use of two-species BGK model in[A.D.Kotelnikov and D.C.Montgomery,A Kinetic Method for Computing Inhomogeneous Fluid ...In this paper,a gas kinetic scheme for the compressible multicomponent flows is presented by making use of two-species BGK model in[A.D.Kotelnikov and D.C.Montgomery,A Kinetic Method for Computing Inhomogeneous Fluid Behavior,J.Comput.Phys.134(1997)364-388].Different from the conventional BGK model,the collisions between different species are taken into consideration.Based on the Chapman-Enskog expansion,the corresponding macroscopic equations are derived from this two-species model.Because of the relaxation terms in the governing equations,the method of operator splitting is applied.In the hyperbolic part,the integral solutions of the BGK equations are used to construct the numerical fluxes at the cell interface in the framework of finite volume method.Numerical tests are presented in this paper to validate the current approach for the compressible multicomponent flows.The theoretical analysis on the spurious oscillations at the interface is also presented.展开更多
We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cau...We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cauchy problem for smooth solutions as well as the existence of deflagration waves, also termed anchored waves. We further discuss related models which have a similar hyperbolic-parabolic structure, notably the Saint- Venant system with a temperature equation as well as the equations governing chemical equilibrium flows. We next investigate multicomponent ionized and magnetized flow models with anisotropic transport fluxes which have a different mathematical structure. We finally discuss numerical algorithms specifically devoted to complex chemistry flows, in particular the evaluation of multicomponent transport properties, as well as the impact of multicomponent transport.展开更多
This paper proposes a robust and efficient oscillation-eliminating discontinuous Galerkin(OEDG)method for solving multicomponent chemically reacting flows,which is an extension and application of the recent work[M.Pen...This paper proposes a robust and efficient oscillation-eliminating discontinuous Galerkin(OEDG)method for solving multicomponent chemically reacting flows,which is an extension and application of the recent work[M.Peng,Z.Sun,and K.Wu,Math.Comput.,2024,doi.org/10.1090/mcom/3998].Following recently developed high-order bound-preserving discontinuous Galerkin method in[J.Du and Y.Yang,J.Comput.Phys.,469(2022),111548],we incorporate an OE procedure after each Runge-–Kutta time stage to suppress spurious oscillations.The OE procedure is defined by the solution operator of a damping equation,which can be analytically solved without requiring discretization,making its implementation straightforward,non-intrusive,and efficient.Through careful design of the damping coefficients,the proposed OEDG method not only achieves the essentially non-oscillatory(ENO)property without compromising accuracy but also preserves the conservative property—an indispensable aspect of the bound-preserving technique introduced in[J.Du and Y.Yang,J.Comput.Phys.,469(2022),111548].The effectiveness and robustness of the OEDG method are demonstrated through a series of one-and two-dimensional numerical tests on the compressible Euler and Navier–Stokes equations for chemically reacting flows.These results highlight the method's capability to handle complex flow dynamics while maintaining stability and high-order accuracy.展开更多
We show that the lattice Boltzmann method(LBM)based color-gradient model with a central moments formulation(CG-CM)is capable of accurately simulating the droplet-on-demand inkjetting process on a micrometer length sca...We show that the lattice Boltzmann method(LBM)based color-gradient model with a central moments formulation(CG-CM)is capable of accurately simulating the droplet-on-demand inkjetting process on a micrometer length scale by comparing it to the Arbitrary Lagrangian Eulerian Finite Element Method(ALE-FEM).A full jetting cycle is simulated using both CG-CM and ALE-FEMand results are quantitatively compared by measuring the ejected ink velocity,volume and contraction rate.We also show that the individual relevant physical phenomena are accurately captured by considering three test-cases;droplet oscillation,ligament contraction and capillary rise.The first two cases test accuracy for a dynamic system where surface tension is the driving force and the third case is designed to test wetting boundary conditions.For the first two cases we also compare the CG-CM and ALE-FEM results to Volume of Fluid(VOF)simulations.Comparison of the three methods shows close agreement when compared to each other and analytical solutions,where available.Finally we demonstrate that asymmetric jetting is achievable using 3D CG-CM simulations utilizing asymmetric wetting conditions inside the jet-nozzle.This allows for systematic investigation into the physics of asymmetric jetting,e.g.due to jet-nozzle manufacturing imperfections or due to other disturbances.展开更多
In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = ...In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = 3） on rectangular parallelepipeds, we show that the mixed method system, by incorporating certain quadrature rules, can be written as a simple, cell-centered finite difference method. This leads to the solution of a sparse, positive semidefinite linear system for the scalar unknown. For a diagonal tensor coefficient, the sparsity pattern for the scalar unknown is a five point stencil if d = 2, and seven if d = 3. For a general tensor coefficient, it is a nine point stencil, and nineteen, respectively. Applications of the mixed method implementation as finite differences to nonisothermal multiphase, multicomponent flow in porous media are presented.展开更多
The performances of the Color-Gradient(CG)and the Shan-Chen(SC)multicomponent Lattice Boltzmann models are quantitatively compared side-by-side on multiple physical flow problems where breakup,coalescence and contract...The performances of the Color-Gradient(CG)and the Shan-Chen(SC)multicomponent Lattice Boltzmann models are quantitatively compared side-by-side on multiple physical flow problems where breakup,coalescence and contraction of fluid ligaments are important.The flow problems are relevant to microfluidic applications,jetting of microdroplets as seen in inkjet printing,as well as emulsion dynamics.A significantly wider range of parameters is shown to be accessible for CG in terms of density-ratio,viscosity-ratio and surface tension values.Numerical stability for a high density ratio O(1000)is required for simulating the drop formation process during inkjet printing which we show here to be achievable using the CG model but not using the SC model.Our results show that the CG model is a suitable choice for challenging simulations of droplet formation,due to a combination of both numerical stability and physical accuracy.We also present a novel approach to incorporate repulsion forces between interfaces for CG,with possible applications to the study of stabilized emulsions.Specifically,we show that the CG model can produce similar results to a known multirange potentials extension of the SC model for modelling a disjoining pressure,opening up its use for the study of dense stabilized emulsions.展开更多
.In this study,we develop computational models and a methodology for accurate multicomponent flow simulation in underresolved multiscale porous structures[1].It is generally impractical to fully resolve the flow in po....In this study,we develop computational models and a methodology for accurate multicomponent flow simulation in underresolved multiscale porous structures[1].It is generally impractical to fully resolve the flow in porous structures with large length-scale differences due to the tremendously high computational expense.The flow contributions from underresolved scales should be taken into account with proper physics modeling and simulation processes.Using precomputed physical properties such as the absolute permeability,K_(0),the capillary pressure-saturation curve,and the relative permeability,K_(r),in typical resolved porous structures,the local fluid force is determined and applied to simulations in the underresolved regions,which are represented by porous media.In this way,accurate flow simulations in multiscale porous structures become feasible.To evaluate the accuracy and robustness of this method,a set of benchmark test cases are simulated for both single-component and two-component flows in artificially constructed multiscale porous structures.Using comparisons with analytic solutions and results with much finer resolution resolving the porous structures,the simulated results are examined.Indeed,in all cases,the results successfully show high accuracy with proper input of K_(0),capillary pressure,and K_(r).Specifically,imbibition patterns,entry pressure,residual component patterns,and absolute/relative permeability are accurately captured with this approach.展开更多
Multicomponent models based on the Lattice Boltzmann Method(LBM)have clear advantages with respect to other approaches,such as good parallel performances and scalability and the automatic resolution of breakup and coa...Multicomponent models based on the Lattice Boltzmann Method(LBM)have clear advantages with respect to other approaches,such as good parallel performances and scalability and the automatic resolution of breakup and coalescence events.Multicomponent flow simulations are useful for a wide range of applications,yet many multicomponent models for LBMare limited in their numerical stability and therefore do not allow exploration of physically relevant low viscosity regimes.Here we performa quantitative study and validations,varying parameters such as viscosity,droplet radius,domain size and acceleration for stationary and translating droplet simulations for the color-gradientmethod with centralmoments(CG-CM)formulation,as this method promises increased numerical stability with respect to the non-CMformulation.We focus on numerical stability and on the effect of decreasing grid-spacing,i.e.increasing resolution,in the extremely low viscosity regime for stationary droplet simulations.The effects of small-and large-scale anisotropy,due to grid-spacing and domain-size,respectively,are investigated for a stationary droplet.The effects on numerical stability of applying a uniform acceleration in one direction on the domain,i.e.on both the droplet and the ambient,is explored into the low viscosity regime,to probe the numerical stability of the method under dynamical conditions.展开更多
We study the static and dynamical behavior of the contact line between two fluids and a solid plate by means of the Lattice Boltzmann method(LBM).The different fluid phases and their contact with the plate are simulat...We study the static and dynamical behavior of the contact line between two fluids and a solid plate by means of the Lattice Boltzmann method(LBM).The different fluid phases and their contact with the plate are simulated by means of standard Shan-Chen models.We investigate different regimes and compare the multicomponent vs.the multiphase LBM models near the contact line.A static interface profile is attained with the multiphase model just by balancing the hydrostatic pressure(due to gravity)with a pressure jump at the bottom.In order to study the same problem with the multicomponent case we propose and validate an idea of a body force acting only on one of the two fluid components.In order to reproduce results matching an infinite bath,boundary conditions at the bath side play a key role.We quantitatively compare open and wall boundary conditions and study their influence on the shape of the meniscus against static and lubrication theory solution.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 12101128)supported by Natural Science Foundation of Fujian Province (Grant No. 2023J02003)National Natural Science Foundation of China (Grant No. 12071392)。
文摘In this paper, we propose a high-order finite volume method for solving multicomponent fluid problems. Our method couples the quasi-conservative form with the reconstruction of conservative variables in a characteristic manner. The source term and numerical fluxes are carefully designed to maintain the pressure and velocity equilibrium for the interface-only problem and preserve the equilibrium of physical parameters in a single-component fluid. These ingredients enable our scheme to achieve both high-order accuracy in the smooth region and the high resolution in the discontinuity region of the solution. Extensive numerical tests are performed to verify the high resolution and accuracy of the scheme.
基金supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (62311)supported by the National Natural Science Foundation of China(51006040)+1 种基金the Hong Kong Scholar Programthe National Science Fund for Distinguished Young Scholars of China (51125024)
文摘In this paper, a pseudopotential-based multiplerelaxation-time lattice Boltzmann model is proposed for multicomponent/multiphase flow systems. Unlike previous models in the literature, the present model not only enables the study of multicomponent flows with different molecular weights, different viscosities and different Schmidt numbers, but also ensures that the distribution function of each component evolves on the same square lattice without invoking ad- ditional interpolations. Furthermore, the Chapman-Enskog analysis shows that the present model results in the correct hydrodynamic equations, and satisfies the indifferentiability principle. The numerical validation exercises further demonstrate that the favorable performance of the present model.
基金supported by an Early Career Faculty grant from NASA's Space Technology Research Grants Programprovided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center
文摘This article focuses on the development of a discontinuous Galerkin (DG) method for simulations of multicomponent and chemically reacting flows. Compared to aerodynamic flow applications, in which DG methods have been successfully employed, DG simulations of chemically reacting flows introduce challenges that arise from flow unsteadiness, combustion, heat release, compressibility effects, shocks, and variations in thermodynamic properties. To address these challenges, algorithms are developed, including an entropy-bounded DG method, an entropy-residual shock indicator, and a new formulation of artificial viscosity. The performance and capabilities of the resulting DG method are demonstrated in several relevant applications, including shock/bubble interaction, turbulent combustion, and detonation. It is concluded that the developed DG method shows promising performance in application to multicomponent reacting flows. The paper concludes with a discussion of further research needs to enable the application of DG methods to more complex reacting flows.
基金supported by the Natural Science Foundation of Hunan Province,China(Grant No.2022JJ40466 and No.2020JJ4235)Research Foundation of Education Bureau of Hunan Province,China(Grant No.21C0213).
文摘This paper presents a pseudopotential lattice Boltzmann analysis to show the deficiency of previous pseudopotential models,i.e.,inconsistency between equilibrium velocity and mixture velocity.To rectify this problem,there are two strategies:decoupling relaxation time and kinematic viscosity or introducing a system mixture relaxation time.Then,we constructed two modified models:a two-relaxationtime(TRT)scheme and a triple-relaxation-time(TriRT)scheme to decouple the relaxation time and kinematic viscosity.Meanwhile,inspired by the idea of a system mixture relaxation time,we developed three mixture models under different collision schemes,viz.mix-SRT,mix-TRT,and mix-TriRT models.Afterwards,we derived the advection-diffusion equation for the multicomponent system and derived the mutual diffusivity in a binarymixture.Finally,we conducted several numerical simulations to validate the analysis on these models.The numerical results show that these models can obtain smaller spurious currents than previous models and have a wider range for the accessible viscosity ratio with fourth-order isotropy.Compared to previous models,presentmodels avoid complex matrix operations and only fourth-order isotropy is required.The increased simplicity and higher computational efficiency of these models make them easy to apply to engineering and industrial applications.
基金Natural Science Foundation of China(NSFC)No.10931004,No.11171037 and No.91130021.
文摘In this paper,a gas kinetic scheme for the compressible multicomponent flows is presented by making use of two-species BGK model in[A.D.Kotelnikov and D.C.Montgomery,A Kinetic Method for Computing Inhomogeneous Fluid Behavior,J.Comput.Phys.134(1997)364-388].Different from the conventional BGK model,the collisions between different species are taken into consideration.Based on the Chapman-Enskog expansion,the corresponding macroscopic equations are derived from this two-species model.Because of the relaxation terms in the governing equations,the method of operator splitting is applied.In the hyperbolic part,the integral solutions of the BGK equations are used to construct the numerical fluxes at the cell interface in the framework of finite volume method.Numerical tests are presented in this paper to validate the current approach for the compressible multicomponent flows.The theoretical analysis on the spurious oscillations at the interface is also presented.
文摘We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cauchy problem for smooth solutions as well as the existence of deflagration waves, also termed anchored waves. We further discuss related models which have a similar hyperbolic-parabolic structure, notably the Saint- Venant system with a temperature equation as well as the equations governing chemical equilibrium flows. We next investigate multicomponent ionized and magnetized flow models with anisotropic transport fluxes which have a different mathematical structure. We finally discuss numerical algorithms specifically devoted to complex chemistry flows, in particular the evaluation of multicomponent transport properties, as well as the impact of multicomponent transport.
基金supported by National Key R&D Program of China(Grant No.2021YFA0719200)supported by the Shenzhen Science and Technology Program(Grant No.RCJC20221008092757098)supported by the Postdoctoral Science Foundation of China(Grant No.2024M751284)。
文摘This paper proposes a robust and efficient oscillation-eliminating discontinuous Galerkin(OEDG)method for solving multicomponent chemically reacting flows,which is an extension and application of the recent work[M.Peng,Z.Sun,and K.Wu,Math.Comput.,2024,doi.org/10.1090/mcom/3998].Following recently developed high-order bound-preserving discontinuous Galerkin method in[J.Du and Y.Yang,J.Comput.Phys.,469(2022),111548],we incorporate an OE procedure after each Runge-–Kutta time stage to suppress spurious oscillations.The OE procedure is defined by the solution operator of a damping equation,which can be analytically solved without requiring discretization,making its implementation straightforward,non-intrusive,and efficient.Through careful design of the damping coefficients,the proposed OEDG method not only achieves the essentially non-oscillatory(ENO)property without compromising accuracy but also preserves the conservative property—an indispensable aspect of the bound-preserving technique introduced in[J.Du and Y.Yang,J.Comput.Phys.,469(2022),111548].The effectiveness and robustness of the OEDG method are demonstrated through a series of one-and two-dimensional numerical tests on the compressible Euler and Navier–Stokes equations for chemically reacting flows.These results highlight the method's capability to handle complex flow dynamics while maintaining stability and high-order accuracy.
基金the Netherlands Organization for Scientific Research(NWO)research project High Tech Systems and Materials(HTSM),with project number 13912the NWO and co-financers Canon Production Printing Holding B.V.,University of Twente and Eindhoven University of Technology for financial support.This work was carried out on the Dutch national e-infrastructure with the support of SURF Cooperative,project number 2021.035。
文摘We show that the lattice Boltzmann method(LBM)based color-gradient model with a central moments formulation(CG-CM)is capable of accurately simulating the droplet-on-demand inkjetting process on a micrometer length scale by comparing it to the Arbitrary Lagrangian Eulerian Finite Element Method(ALE-FEM).A full jetting cycle is simulated using both CG-CM and ALE-FEMand results are quantitatively compared by measuring the ejected ink velocity,volume and contraction rate.We also show that the individual relevant physical phenomena are accurately captured by considering three test-cases;droplet oscillation,ligament contraction and capillary rise.The first two cases test accuracy for a dynamic system where surface tension is the driving force and the third case is designed to test wetting boundary conditions.For the first two cases we also compare the CG-CM and ALE-FEM results to Volume of Fluid(VOF)simulations.Comparison of the three methods shows close agreement when compared to each other and analytical solutions,where available.Finally we demonstrate that asymmetric jetting is achievable using 3D CG-CM simulations utilizing asymmetric wetting conditions inside the jet-nozzle.This allows for systematic investigation into the physics of asymmetric jetting,e.g.due to jet-nozzle manufacturing imperfections or due to other disturbances.
文摘In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = 3） on rectangular parallelepipeds, we show that the mixed method system, by incorporating certain quadrature rules, can be written as a simple, cell-centered finite difference method. This leads to the solution of a sparse, positive semidefinite linear system for the scalar unknown. For a diagonal tensor coefficient, the sparsity pattern for the scalar unknown is a five point stencil if d = 2, and seven if d = 3. For a general tensor coefficient, it is a nine point stencil, and nineteen, respectively. Applications of the mixed method implementation as finite differences to nonisothermal multiphase, multicomponent flow in porous media are presented.
基金part of the Netherlands Organization for Scientific Research(NWO)research project High Tech Systems and Materials(HTSM),with project number 13912the NWO and co-financers Canon Production Printing Holding B.V.,University of Twente and Eindhoven University of Technology for financial support.
文摘The performances of the Color-Gradient(CG)and the Shan-Chen(SC)multicomponent Lattice Boltzmann models are quantitatively compared side-by-side on multiple physical flow problems where breakup,coalescence and contraction of fluid ligaments are important.The flow problems are relevant to microfluidic applications,jetting of microdroplets as seen in inkjet printing,as well as emulsion dynamics.A significantly wider range of parameters is shown to be accessible for CG in terms of density-ratio,viscosity-ratio and surface tension values.Numerical stability for a high density ratio O(1000)is required for simulating the drop formation process during inkjet printing which we show here to be achievable using the CG model but not using the SC model.Our results show that the CG model is a suitable choice for challenging simulations of droplet formation,due to a combination of both numerical stability and physical accuracy.We also present a novel approach to incorporate repulsion forces between interfaces for CG,with possible applications to the study of stabilized emulsions.Specifically,we show that the CG model can produce similar results to a known multirange potentials extension of the SC model for modelling a disjoining pressure,opening up its use for the study of dense stabilized emulsions.
文摘.In this study,we develop computational models and a methodology for accurate multicomponent flow simulation in underresolved multiscale porous structures[1].It is generally impractical to fully resolve the flow in porous structures with large length-scale differences due to the tremendously high computational expense.The flow contributions from underresolved scales should be taken into account with proper physics modeling and simulation processes.Using precomputed physical properties such as the absolute permeability,K_(0),the capillary pressure-saturation curve,and the relative permeability,K_(r),in typical resolved porous structures,the local fluid force is determined and applied to simulations in the underresolved regions,which are represented by porous media.In this way,accurate flow simulations in multiscale porous structures become feasible.To evaluate the accuracy and robustness of this method,a set of benchmark test cases are simulated for both single-component and two-component flows in artificially constructed multiscale porous structures.Using comparisons with analytic solutions and results with much finer resolution resolving the porous structures,the simulated results are examined.Indeed,in all cases,the results successfully show high accuracy with proper input of K_(0),capillary pressure,and K_(r).Specifically,imbibition patterns,entry pressure,residual component patterns,and absolute/relative permeability are accurately captured with this approach.
基金the Netherlands Organization for Scientific Research(NWO)research project High Tech Systems and Materials(HTSM),with project number 13912.
文摘Multicomponent models based on the Lattice Boltzmann Method(LBM)have clear advantages with respect to other approaches,such as good parallel performances and scalability and the automatic resolution of breakup and coalescence events.Multicomponent flow simulations are useful for a wide range of applications,yet many multicomponent models for LBMare limited in their numerical stability and therefore do not allow exploration of physically relevant low viscosity regimes.Here we performa quantitative study and validations,varying parameters such as viscosity,droplet radius,domain size and acceleration for stationary and translating droplet simulations for the color-gradientmethod with centralmoments(CG-CM)formulation,as this method promises increased numerical stability with respect to the non-CMformulation.We focus on numerical stability and on the effect of decreasing grid-spacing,i.e.increasing resolution,in the extremely low viscosity regime for stationary droplet simulations.The effects of small-and large-scale anisotropy,due to grid-spacing and domain-size,respectively,are investigated for a stationary droplet.The effects on numerical stability of applying a uniform acceleration in one direction on the domain,i.e.on both the droplet and the ambient,is explored into the low viscosity regime,to probe the numerical stability of the method under dynamical conditions.
基金funded by FOM(Foundation for Fundamental Research on Matter).
文摘We study the static and dynamical behavior of the contact line between two fluids and a solid plate by means of the Lattice Boltzmann method(LBM).The different fluid phases and their contact with the plate are simulated by means of standard Shan-Chen models.We investigate different regimes and compare the multicomponent vs.the multiphase LBM models near the contact line.A static interface profile is attained with the multiphase model just by balancing the hydrostatic pressure(due to gravity)with a pressure jump at the bottom.In order to study the same problem with the multicomponent case we propose and validate an idea of a body force acting only on one of the two fluid components.In order to reproduce results matching an infinite bath,boundary conditions at the bath side play a key role.We quantitatively compare open and wall boundary conditions and study their influence on the shape of the meniscus against static and lubrication theory solution.
