An additional potential energy distribution function is introduced on the basis of previous D3Q25 model,and the equilibrium distribution function of D3Q25 is obtained by spherical function.A novel three-dimensional(3D...An additional potential energy distribution function is introduced on the basis of previous D3Q25 model,and the equilibrium distribution function of D3Q25 is obtained by spherical function.A novel three-dimensional(3D)shifted lattice model is proposed,therefore a shifted lattice model is introduced into D3Q25.Under the finite volume scheme,several typical compressible calculation examples are used to verify whether the numerical stability of the D3Q25 model can be improved by adding the shifted lattice model.The simulation results show that the numerical stability is indeed improved after adding the shifted lattice model.展开更多
A new lattice Boltzmann model for compressible perfect gas is proposed. The numerical example shows that it can be used to simulate shock wave and contact discontinuity. The results are comparable with those obtained ...A new lattice Boltzmann model for compressible perfect gas is proposed. The numerical example shows that it can be used to simulate shock wave and contact discontinuity. The results are comparable with those obtained by traditional methods. The ratio of specific heats gamma may be chosen according to the requirement of problems.展开更多
A highly efficient three-dimensional (3D) Lattice Boltzmann (LB) model for high-speed compressible Sowsis proposed.This model is developed from the original one by Kataoka and Tsutahara [Phys.Rev.E 69 (2004) 056702].T...A highly efficient three-dimensional (3D) Lattice Boltzmann (LB) model for high-speed compressible Sowsis proposed.This model is developed from the original one by Kataoka and Tsutahara [Phys.Rev.E 69 (2004) 056702].The convection term is discretized by the Non-oscillatory, containing No free parameters and Dissipative (NND) scheme,which effectively damps oscillations at discontinuities.To be more consistent with the kinetic theory of viscosity and tofurther improve the numerical stability, an additional dissipation term is introduced.Model parameters are chosen insuch a way that the von Neumann stability criterion is satisfied.The new model is validated by well-known benchmarks,(i) Riemann problems, including the problem with Lax shock tube and a newly designed shock tube problem with highMach number; (ii) reaction of shock wave on droplet or bubble.Good agreements are obtained between LB results andexact ones or previously reported solutions.The model is capable of simulating flows from subsonic to supersonic andcapturing jumps resulted from shock waves.展开更多
The optical flow analysis of the image sequence based on the formal lattice Boltzmann equation, with different DdQm models, is discussed in this paper. The Mgorithm is based on the lattice Boltzmann method (LBM), wh...The optical flow analysis of the image sequence based on the formal lattice Boltzmann equation, with different DdQm models, is discussed in this paper. The Mgorithm is based on the lattice Boltzmann method (LBM), which is used in computational fluid dynamics theory for the simulation of fluid dynamics. At first, a generalized approximation to the formal lattice Boltzmann equation is discussed. Then the effects of different DdQm models on the results of the optical flow estimation are compared with each other, while calculating the movement vectors of pixels in the image sequence. The experimental results show that the higher dimension DdQm models, e.g., D3Q15 are more effective than those lower dimension ones.展开更多
In this mini-review we summarize the progress of Lattice Boltzmann (LB) modeling and simulating compressible flows in our group in recent years. Main contents include (i) Single-Relaxation-Time (SRT) LB model su...In this mini-review we summarize the progress of Lattice Boltzmann (LB) modeling and simulating compressible flows in our group in recent years. Main contents include (i) Single-Relaxation-Time (SRT) LB model supplemented by additional viscosity, (ii) Multiple-Relaxation-Time (MRT) LB model, and (iii) LB study on hydrodynamic instabilities. The former two belong to improvements of physical modeling and the third belongs to simulation or application. The SRT-LB model sup- plemented by additional viscosity keeps the original framework of Lattice Bhatnagar-Gross Krook (LBGK). So, it is easier and more convenient for previous SRT-LB users. The MRT-LB is a com- pletely new framework for physical modeling. It significantly extends the range of LB applications. The cost is longer computational time. The developed SRT-LB and MRT-LB are complementary from the sides of convenience and applicability.展开更多
A combined lattice Boltzmann and discrete element approach is proposedfor numerical modelling of magnetorheological fluids. In its formulation, the particledynamics is simulated by the discrete element method, while t...A combined lattice Boltzmann and discrete element approach is proposedfor numerical modelling of magnetorheological fluids. In its formulation, the particledynamics is simulated by the discrete element method, while the fluid field is resolvedwith the lattice Boltzmann method. The coupling between the fluid and the particlesare realized through the hydrodynamic interactions. Procedures for computing magnetic, contact and hydrodynamic forces are discussed in detail. The applicability ofthe proposed solution procedure is illustrated via a two-stage simulation of a MR fluidproblem with four different particle volume fractions. At the first stage, simulationsare performed for the particle chain formation upon application of an external magnetic field;and at the second stage, the rheological properties of the MR fluid underdifferent shear loading conditions are investigated with the particle chains establishedat the first stage as the initial configuration.展开更多
The aims of the present paper are threefold. First, we further study the fast Fourier transform thermal lattice Boltzmann (FFT-TLB) model for van der Waals (VDW) fluids proposed in Phys. Rev. E, 2011, 84(4): 04...The aims of the present paper are threefold. First, we further study the fast Fourier transform thermal lattice Boltzmann (FFT-TLB) model for van der Waals (VDW) fluids proposed in Phys. Rev. E, 2011, 84(4): 046715. We analyze the merits of the FFT approach over the traditional finite difference scheme and investigate the effects of smoothing factors on accuracy and stability in detail. Second, we incorporate the VDW equation of state with flexible parameters into the FFT- TLB model. As a result, the revised model may be used to handle multiphase flows with various critical densities and temperatures. Third, we design appropriate boundary conditions for systems with solid walls. These improvements, from the views of numerics and physics, significantly extend the application scope of the model in science and engineering.展开更多
SUMMARY: Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet's future energy demands that a key geophysical problem be solved first: how to develop and mai...SUMMARY: Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet's future energy demands that a key geophysical problem be solved first: how to develop and maintain a network of multiple fluid flow pathways for the time required to deplete the heat within a given region. We present the key components for micro-scale particle-based numerical modeling of hydraulic fracture, and fluid and heat flow in geothermal reservoirs. They are based on the latest developments of ESyS-Particle--the coupling of the lattice sofid model (LSM) to simulate the nonlinear dynamics of complex solids with the lattice Boltzmann method (LBM) applied to the nonlinear dynamics of coupled fluid and heat flow in the complex solid-fluid system. The coupled LSM/LBM can be used to simulate development of fracture systems in discontinuous media, elastic stress release, fluid injection and the consequent slip at joint surfaces, and hydraulic fractur- ing; heat exchange between hot rocks and water within flow pathways created through hydraulic fracturing; and fluid flow through complex, narrow, compact and gouge- or powder-f'flled fracture and joint systems. We demonstrate the coupled LSM/LBM to simulate the fundamental processes listed above, which are all components for the generation and sustainability of the hot-fractured rock geothermal energy fracture systems required to exploit this new green-energy resource.展开更多
In this paper,we present a Cole-Hopf transformation based lattice Boltzmann(LB) model for solving one-dimensional Burgers' equation,and compared to available LB models,the effect of nonlinear convection term can b...In this paper,we present a Cole-Hopf transformation based lattice Boltzmann(LB) model for solving one-dimensional Burgers' equation,and compared to available LB models,the effect of nonlinear convection term can be eliminated.Through Chapman-Enskog analysis,it can be found that the converted diffusion equation based on the Cole-Hopf transformation can be recovered correctly from present LB model.Some numerical tests are also performed to validate the present LB model,and the numerical results show that,similar to previous LB models,the present model also has a second-order convergence rate in space,but it is more accurate than the previous ones.展开更多
In this paper, we consider a one-dimensional nonlinear partial differential equation that has the form ut + αuux + βunux - γuxx + δuxxx = F(u). A higher order lattice Bhatnager-Gross-Krook (BGK) model with an amen...In this paper, we consider a one-dimensional nonlinear partial differential equation that has the form ut + αuux + βunux - γuxx + δuxxx = F(u). A higher order lattice Bhatnager-Gross-Krook (BGK) model with an amending-function is proposed. With the Chapman-Enskog expansion, different kinds of nonlinear partial differential equations are recovered correctly from the continuous Boltzmann equation. The numerical results show that this method is very effective.展开更多
The linear barotropic vorticity equation describing wind-driven oceancirculation is considered as a convection-diffusion equation that can be numerically solved bylattice Boltzmann method. Numerical experiments are ca...The linear barotropic vorticity equation describing wind-driven oceancirculation is considered as a convection-diffusion equation that can be numerically solved bylattice Boltzmann method. Numerical experiments are carried out to examine the validity of the modelfor the wind-driven circulation. When horizontal viscosity is constant and spatially uniform, allnumerical solutions for different parameters approach analytical solutions well. The spatiallyvarying horizontal viscosity is also included in this model. It is shown that the variant horizontalviscosity increases the meridional transport significantly in west boundary current. By theinvestigation of numerical results, it was concluded that this model is competent for simulatingwestern boundary current.展开更多
A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by t...A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM), Particle-fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle-fluid systems.展开更多
The derivation of the quantum lattice Boltzmann model is reviewed with special emphasis on recent developments of the model,namely,the extension to a multi-dimensional formulation and the application to the computatio...The derivation of the quantum lattice Boltzmann model is reviewed with special emphasis on recent developments of the model,namely,the extension to a multi-dimensional formulation and the application to the computation of the ground state of the Gross-Pitaevskii equation(GPE).Numerical results for the linear and nonlinear Schr odinger equation and for the ground state solution of the GPE are also presented and validated against analytical results or other classical schemes such as Crank-Nicholson.展开更多
Fresh cement mortar is a type of workable paste,which can be well approximated as a Bingham plastic and whose flow behavior is of major concern in engineering.In this paper,Papanastasiou’s model for Bingham fluids is...Fresh cement mortar is a type of workable paste,which can be well approximated as a Bingham plastic and whose flow behavior is of major concern in engineering.In this paper,Papanastasiou’s model for Bingham fluids is solved by using the multiplerelaxation-time lattice Boltzmann model(MRT-LB).Analysis of the stress growth exponent m in Bingham fluid flow simulations shows that Papanastasiou’s model provides a good approximation of realistic Bingham plastics for values of m>108.For lower values of m,Papanastasiou’s model is valid for fluids between Bingham and Newtonian fluids.The MRT-LB model is validated by two benchmark problems:2D steady Poiseuille flows and lid-driven cavity flows.Comparing the numerical results of the velocity distributions with corresponding analytical solutions shows that the MRT-LB model is appropriate for studying Bingham fluids while also providing better numerical stability.We further apply the MRT-LB model to simulate flow through a sudden expansion channel and the flow surrounding a round particle.Besides the rich flow structures obtained in this work,the dynamics fluid force on the round particle is calculated.Results show that both the Reynolds number Re and the Bingham number Bn afect the drag coefcients CD,and a drag coefcient with Re and Bn being taken into account is proposed.The relationship of Bn and the ratio of unyielded zone thickness to particle diameter is also analyzed.Finally,the Bingham fluid flowing around a set of randomly dispersed particles is simulated to obtain the apparent viscosity and velocity fields.These results help simulation of fresh concrete flowing in porous media.展开更多
A lattice Boltzmann flux solver(LBFS)is presented for simulation of fluid flows.Like the conventional computational fluid dynamics(CFD)solvers,the new solver also applies the finite volume method to discretize the gov...A lattice Boltzmann flux solver(LBFS)is presented for simulation of fluid flows.Like the conventional computational fluid dynamics(CFD)solvers,the new solver also applies the finite volume method to discretize the governing differential equations,but the numerical flux at the cell interface is not evaluated by the smooth function approximation or Riemann solvers.Instead,it is evaluated from local solution of lattice Boltzmann equation(LBE)at cell interface.Two versions of LBFS are presented in this paper.One is to locally apply one-dimensional compressible lattice Boltzmann(LB)model along the normal direction to the cell interface for simulation of compressible inviscid flows with shock waves.The other is to locally apply multi-dimensional LB model at cell interface for simulation of incompressible viscous and inviscid flows.The present solver removes the drawbacks of conventional lattice Boltzmann method(LBM)such as limitation to uniform mesh,tie-up of mesh spacing and time interval,limitation to viscous flows.Numerical examples show that the present solver can be well applied to simulate fluid flows with non-uniform mesh and curved boundary.展开更多
In this paper,the lattice-Boltzmann method is used to investigate the droplet dynamics after impact on horizontal and inclined solid surface. The two-phase interparticle potential model is employed. The model is found...In this paper,the lattice-Boltzmann method is used to investigate the droplet dynamics after impact on horizontal and inclined solid surface. The two-phase interparticle potential model is employed. The model is found to possess a linear relation between the macroscopic properties( surface tension σ and contact angle α)and microscopic parameters( G,G t). The flow state of the droplet on the surface is analyzed in detail,and the effects of surface characteristic,impact velocity,impact angle,the viscosity and surface tension of the liquid are investigated,respectively. It is shown that the lattice-Boltzmann method can not only track exactly and automatically the interface,but also the simulation results have a good qualitative agreement with ones of the previous experimental and numerical studies.展开更多
基金the Youth Program of the National Natural Science Foundation of China(Grant Nos.11972272,12072246,and 12202331)the National Key Project,China(Grant No.GJXM92579)the Natural Science Basic Research Program of Shaanxi Province,China(Program No.2022JQ-028)。
文摘An additional potential energy distribution function is introduced on the basis of previous D3Q25 model,and the equilibrium distribution function of D3Q25 is obtained by spherical function.A novel three-dimensional(3D)shifted lattice model is proposed,therefore a shifted lattice model is introduced into D3Q25.Under the finite volume scheme,several typical compressible calculation examples are used to verify whether the numerical stability of the D3Q25 model can be improved by adding the shifted lattice model.The simulation results show that the numerical stability is indeed improved after adding the shifted lattice model.
基金The project supported by the National Natural Science Foundation of China
文摘A new lattice Boltzmann model for compressible perfect gas is proposed. The numerical example shows that it can be used to simulate shock wave and contact discontinuity. The results are comparable with those obtained by traditional methods. The ratio of specific heats gamma may be chosen according to the requirement of problems.
基金Supported by the Science Foundations of Laboratory of Computational PhysicalScience Foundation of China Academy of Engineering Physics under Grant Nos. 2009A0102005, 2009B0101012National Natural Science Foundation under Grant Nos. 10775018, 11074300, and 1107521 of China
文摘A highly efficient three-dimensional (3D) Lattice Boltzmann (LB) model for high-speed compressible Sowsis proposed.This model is developed from the original one by Kataoka and Tsutahara [Phys.Rev.E 69 (2004) 056702].The convection term is discretized by the Non-oscillatory, containing No free parameters and Dissipative (NND) scheme,which effectively damps oscillations at discontinuities.To be more consistent with the kinetic theory of viscosity and tofurther improve the numerical stability, an additional dissipation term is introduced.Model parameters are chosen insuch a way that the von Neumann stability criterion is satisfied.The new model is validated by well-known benchmarks,(i) Riemann problems, including the problem with Lax shock tube and a newly designed shock tube problem with highMach number; (ii) reaction of shock wave on droplet or bubble.Good agreements are obtained between LB results andexact ones or previously reported solutions.The model is capable of simulating flows from subsonic to supersonic andcapturing jumps resulted from shock waves.
基金Project supported by the National Natural Science Foundation of China(Grant No.40976108)the Shanghai Leading Academic Discipline Project(Grant No.J50103)the Innovation Program of Municipal Education Commission of Shanghai Municipality(Grant No.11YZ03)
文摘The optical flow analysis of the image sequence based on the formal lattice Boltzmann equation, with different DdQm models, is discussed in this paper. The Mgorithm is based on the lattice Boltzmann method (LBM), which is used in computational fluid dynamics theory for the simulation of fluid dynamics. At first, a generalized approximation to the formal lattice Boltzmann equation is discussed. Then the effects of different DdQm models on the results of the optical flow estimation are compared with each other, while calculating the movement vectors of pixels in the image sequence. The experimental results show that the higher dimension DdQm models, e.g., D3Q15 are more effective than those lower dimension ones.
文摘In this mini-review we summarize the progress of Lattice Boltzmann (LB) modeling and simulating compressible flows in our group in recent years. Main contents include (i) Single-Relaxation-Time (SRT) LB model supplemented by additional viscosity, (ii) Multiple-Relaxation-Time (MRT) LB model, and (iii) LB study on hydrodynamic instabilities. The former two belong to improvements of physical modeling and the third belongs to simulation or application. The SRT-LB model sup- plemented by additional viscosity keeps the original framework of Lattice Bhatnagar-Gross Krook (LBGK). So, it is easier and more convenient for previous SRT-LB users. The MRT-LB is a com- pletely new framework for physical modeling. It significantly extends the range of LB applications. The cost is longer computational time. The developed SRT-LB and MRT-LB are complementary from the sides of convenience and applicability.
文摘A combined lattice Boltzmann and discrete element approach is proposedfor numerical modelling of magnetorheological fluids. In its formulation, the particledynamics is simulated by the discrete element method, while the fluid field is resolvedwith the lattice Boltzmann method. The coupling between the fluid and the particlesare realized through the hydrodynamic interactions. Procedures for computing magnetic, contact and hydrodynamic forces are discussed in detail. The applicability ofthe proposed solution procedure is illustrated via a two-stage simulation of a MR fluidproblem with four different particle volume fractions. At the first stage, simulationsare performed for the particle chain formation upon application of an external magnetic field;and at the second stage, the rheological properties of the MR fluid underdifferent shear loading conditions are investigated with the particle chains establishedat the first stage as the initial configuration.
文摘The aims of the present paper are threefold. First, we further study the fast Fourier transform thermal lattice Boltzmann (FFT-TLB) model for van der Waals (VDW) fluids proposed in Phys. Rev. E, 2011, 84(4): 046715. We analyze the merits of the FFT approach over the traditional finite difference scheme and investigate the effects of smoothing factors on accuracy and stability in detail. Second, we incorporate the VDW equation of state with flexible parameters into the FFT- TLB model. As a result, the revised model may be used to handle multiphase flows with various critical densities and temperatures. Third, we design appropriate boundary conditions for systems with solid walls. These improvements, from the views of numerics and physics, significantly extend the application scope of the model in science and engineering.
文摘SUMMARY: Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet's future energy demands that a key geophysical problem be solved first: how to develop and maintain a network of multiple fluid flow pathways for the time required to deplete the heat within a given region. We present the key components for micro-scale particle-based numerical modeling of hydraulic fracture, and fluid and heat flow in geothermal reservoirs. They are based on the latest developments of ESyS-Particle--the coupling of the lattice sofid model (LSM) to simulate the nonlinear dynamics of complex solids with the lattice Boltzmann method (LBM) applied to the nonlinear dynamics of coupled fluid and heat flow in the complex solid-fluid system. The coupled LSM/LBM can be used to simulate development of fracture systems in discontinuous media, elastic stress release, fluid injection and the consequent slip at joint surfaces, and hydraulic fractur- ing; heat exchange between hot rocks and water within flow pathways created through hydraulic fracturing; and fluid flow through complex, narrow, compact and gouge- or powder-f'flled fracture and joint systems. We demonstrate the coupled LSM/LBM to simulate the fundamental processes listed above, which are all components for the generation and sustainability of the hot-fractured rock geothermal energy fracture systems required to exploit this new green-energy resource.
基金Supported by the National Natural Science Foundation of China under Grant No.51576079
文摘In this paper,we present a Cole-Hopf transformation based lattice Boltzmann(LB) model for solving one-dimensional Burgers' equation,and compared to available LB models,the effect of nonlinear convection term can be eliminated.Through Chapman-Enskog analysis,it can be found that the converted diffusion equation based on the Cole-Hopf transformation can be recovered correctly from present LB model.Some numerical tests are also performed to validate the present LB model,and the numerical results show that,similar to previous LB models,the present model also has a second-order convergence rate in space,but it is more accurate than the previous ones.
基金Supported by the National Natural Science Foundation of China (Grant No 10661005) the Science and Technology Plan Item of Fujian Province (Grant No 2008F5019)
文摘In this paper, we consider a one-dimensional nonlinear partial differential equation that has the form ut + αuux + βunux - γuxx + δuxxx = F(u). A higher order lattice Bhatnager-Gross-Krook (BGK) model with an amending-function is proposed. With the Chapman-Enskog expansion, different kinds of nonlinear partial differential equations are recovered correctly from the continuous Boltzmann equation. The numerical results show that this method is very effective.
文摘The linear barotropic vorticity equation describing wind-driven oceancirculation is considered as a convection-diffusion equation that can be numerically solved bylattice Boltzmann method. Numerical experiments are carried out to examine the validity of the modelfor the wind-driven circulation. When horizontal viscosity is constant and spatially uniform, allnumerical solutions for different parameters approach analytical solutions well. The spatiallyvarying horizontal viscosity is also included in this model. It is shown that the variant horizontalviscosity increases the meridional transport significantly in west boundary current. By theinvestigation of numerical results, it was concluded that this model is competent for simulatingwestern boundary current.
基金sponsored by Ministry of Finance under the grant ZDYZ2008-2National Key Science and Technology Project under the grant 2008ZX05014-003-006HZthe Chinese Academy of Sciences under the grant KGCX2-YW-124
文摘A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM), Particle-fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle-fluid systems.
文摘The derivation of the quantum lattice Boltzmann model is reviewed with special emphasis on recent developments of the model,namely,the extension to a multi-dimensional formulation and the application to the computation of the ground state of the Gross-Pitaevskii equation(GPE).Numerical results for the linear and nonlinear Schr odinger equation and for the ground state solution of the GPE are also presented and validated against analytical results or other classical schemes such as Crank-Nicholson.
基金supported by the National Key Basic Research Program of China(Grant No.2010CB731504)the Natural Science Foundation of China(Grant Nos.11034010,11272048 and 51239006)+1 种基金European Commission Marie Curie Actions(Grant No.IRSES-294976)the State Key Laboratory of Hydroscience and Engineering(Grant No.2013-KY-2)
文摘Fresh cement mortar is a type of workable paste,which can be well approximated as a Bingham plastic and whose flow behavior is of major concern in engineering.In this paper,Papanastasiou’s model for Bingham fluids is solved by using the multiplerelaxation-time lattice Boltzmann model(MRT-LB).Analysis of the stress growth exponent m in Bingham fluid flow simulations shows that Papanastasiou’s model provides a good approximation of realistic Bingham plastics for values of m>108.For lower values of m,Papanastasiou’s model is valid for fluids between Bingham and Newtonian fluids.The MRT-LB model is validated by two benchmark problems:2D steady Poiseuille flows and lid-driven cavity flows.Comparing the numerical results of the velocity distributions with corresponding analytical solutions shows that the MRT-LB model is appropriate for studying Bingham fluids while also providing better numerical stability.We further apply the MRT-LB model to simulate flow through a sudden expansion channel and the flow surrounding a round particle.Besides the rich flow structures obtained in this work,the dynamics fluid force on the round particle is calculated.Results show that both the Reynolds number Re and the Bingham number Bn afect the drag coefcients CD,and a drag coefcient with Re and Bn being taken into account is proposed.The relationship of Bn and the ratio of unyielded zone thickness to particle diameter is also analyzed.Finally,the Bingham fluid flowing around a set of randomly dispersed particles is simulated to obtain the apparent viscosity and velocity fields.These results help simulation of fresh concrete flowing in porous media.
文摘引入了一种二元Lattice Boltzmann Model(LBM),实现了两种液体组成的混合流的模拟.不同于其它的类似模型,它区分考虑了流体的粘性和扩散特性,可以很容易地模拟各种互溶或者不互溶的混合流现象.此外,由于LBM的运算大都是线性的局部运算,这使得它很容易在可编程图形处理器(Graphics Process Unit,GPU)上进行加速,从而进行实时模拟.给出了若干二元混合流的模拟结果.
基金Supported by the National Natural Science Foundation of China(11272153)
文摘A lattice Boltzmann flux solver(LBFS)is presented for simulation of fluid flows.Like the conventional computational fluid dynamics(CFD)solvers,the new solver also applies the finite volume method to discretize the governing differential equations,but the numerical flux at the cell interface is not evaluated by the smooth function approximation or Riemann solvers.Instead,it is evaluated from local solution of lattice Boltzmann equation(LBE)at cell interface.Two versions of LBFS are presented in this paper.One is to locally apply one-dimensional compressible lattice Boltzmann(LB)model along the normal direction to the cell interface for simulation of compressible inviscid flows with shock waves.The other is to locally apply multi-dimensional LB model at cell interface for simulation of incompressible viscous and inviscid flows.The present solver removes the drawbacks of conventional lattice Boltzmann method(LBM)such as limitation to uniform mesh,tie-up of mesh spacing and time interval,limitation to viscous flows.Numerical examples show that the present solver can be well applied to simulate fluid flows with non-uniform mesh and curved boundary.
基金Sponsored by the National Nature Science Foundation of China(Grant No.51276030,51176017)
文摘In this paper,the lattice-Boltzmann method is used to investigate the droplet dynamics after impact on horizontal and inclined solid surface. The two-phase interparticle potential model is employed. The model is found to possess a linear relation between the macroscopic properties( surface tension σ and contact angle α)and microscopic parameters( G,G t). The flow state of the droplet on the surface is analyzed in detail,and the effects of surface characteristic,impact velocity,impact angle,the viscosity and surface tension of the liquid are investigated,respectively. It is shown that the lattice-Boltzmann method can not only track exactly and automatically the interface,but also the simulation results have a good qualitative agreement with ones of the previous experimental and numerical studies.