A complete boundary integral formulation for steady compressible inviscid flows governed by nonlinear equations is established by using ρV as variable. Thus, the dimensionality of the problem to be solved is reduced ...A complete boundary integral formulation for steady compressible inviscid flows governed by nonlinear equations is established by using ρV as variable. Thus, the dimensionality of the problem to be solved is reduced by one and the computational mesh to be generated is needed only on the boundary of the domain.展开更多
In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,incl...In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,including inviscid LBFS Ⅰ,viscous LBFS Ⅱ,hybrid LBFS Ⅲ and hybrid LBFS Ⅳ.Hybrid LBFS can automatically realize the switch between inviscid LBFS Ⅰ and viscous LBFS Ⅱ through introducing a switch function.The resultant hybrid WENO-LBFS scheme absorbs the advantages of WENO scheme and hybrid LBFS.We investigate the performance of WENO scheme based on four kinds of LBFS systematically.Numerical results indicate that the devopled hybrid WENO-LBFS scheme has high accuracy,high resolution and no oscillations.It can not only accurately calculate smooth solutions,but also can effectively capture contact discontinuities and strong shock waves.展开更多
In this paper,an immersed boundary algorithm is developed by combining the ghost cell method with adaptive tree Cartesian grid method.Furthermore,the proposed method is successfully used to evaluate various inviscid c...In this paper,an immersed boundary algorithm is developed by combining the ghost cell method with adaptive tree Cartesian grid method.Furthermore,the proposed method is successfully used to evaluate various inviscid compressible flow with immersed boundary.The extension to three dimensional cases is also achieved.Numerical examples demonstrate the proposed method is effective.展开更多
This paper presents a robust sharp-interface immersed boundary method for simulating inviscid compressible flows over stationary and moving bodies.The flow field is governed by Euler equations,which are solved by usin...This paper presents a robust sharp-interface immersed boundary method for simulating inviscid compressible flows over stationary and moving bodies.The flow field is governed by Euler equations,which are solved by using the open source library OpenFOAM.Discontinuities such as those introduced by shock waves are captured by using Kurganov and Tadmor divergence scheme.Wall-slip boundary conditions are enforced at the boundary of body through reconstructing flow variables at some ghost points.Their values are obtained indirectly by interpolating from their mirror points.A bilinear interpolation is employed to determine the variables at the mirror points from boundary conditions and flow conditions around the boundary.To validate the efficiency and accuracy of this method for simulation of high-speed inviscid compressible flows,four cases have been simulated as follows:supersonic flow over a 15°angle wedge,transonic flow past a stationary airfoil,a piston moving with supersonic velocity in a shock tube and a rigid circular cylinder lift-off from a flat surface triggered by a shock wave.Compared to the exact analytical solutions or the results in literature,good agreement can be achieved.展开更多
This paper at first shows the details of finite volume-based lattice Boltzmann method(FV-LBM)for simulation of compressible flows with shock waves.In the FV-LBM,the normal convective flux at the interface of a cell is...This paper at first shows the details of finite volume-based lattice Boltzmann method(FV-LBM)for simulation of compressible flows with shock waves.In the FV-LBM,the normal convective flux at the interface of a cell is evaluated by using one-dimensional compressible lattice Boltzmann model,while the tangential flux is calculated using the same way as used in the conventional Euler solvers.The paper then presents a platform to construct one-dimensional compressible lattice Boltzmann model for its use in FV-LBM.The platform is formed from the conservation forms of moments.Under the platform,both the equilibrium distribution functions and lattice velocities can be determined,and therefore,non-free parameter model can be developed.The paper particularly presents three typical non-free parameter models,D1Q3,D1Q4 and D1Q5.The performances of these three models for simulation of compressible flows are investigated by a brief analysis and their application to solve some one-dimensional and two-dimensional test problems.Numerical results showed that D1Q3 model costs the least computation time and D1Q4 and D1Q5 models have the wider application range of Mach number.From the results,it seems that D1Q4 model could be the best choice for the FVLBM simulation of hypersonic flows.展开更多
This paper concerns the inviscid,heat conductive and resistive compressible MHD system in a horizontally periodic flat strip domain.The global well-posedness of the problem around an equilibrium with the positive cons...This paper concerns the inviscid,heat conductive and resistive compressible MHD system in a horizontally periodic flat strip domain.The global well-posedness of the problem around an equilibrium with the positive constant density and temperature and a uniform non-horizontal magnetic field is established,and the solution decays to the equilibrium almost exponentially.Our result reveals the strong stabilizing effect of the transversal magnetic field and resistivity as the global well-posedness of compressible inviscid heat-conductive flows in multi-D is unknown.展开更多
A compressible and multiphase flows solver has been developed for the study of liquid/gas flows involving shock waves and strong expansion waves leading to cavitation.This solver has a structure similar to those of th...A compressible and multiphase flows solver has been developed for the study of liquid/gas flows involving shock waves and strong expansion waves leading to cavitation.This solver has a structure similar to those of the one-fluid Euler solvers,differing from them by the presence of a void ratio transport-equation.The model and the system of equations to be simulated are presented.Results are displayed for shock and expansion tube problems,shock-bubble interaction and underwater explosion.Close agreement with reference solutions,obtained from explicit finite volume approaches,is demonstrated.Different numerical methods are additionally displayed to provide comparable and improved computational efficiency to the model and the system of equations.The overall procedure is therefore very well suited for use in general two-phase fluid flow simulations.展开更多
For compressible reactive flows with stiff source terms,a new block-based adaptive multi-resolution method coupled with the adaptive multi-resolution representation model for ZND detonation and a conservative front ca...For compressible reactive flows with stiff source terms,a new block-based adaptive multi-resolution method coupled with the adaptive multi-resolution representation model for ZND detonation and a conservative front capturing method based on a level-set technique is presented.When simulating stiff reactive flows,underresolution in space and time can lead to incorrect propagation speeds of discontinuities,and numerical dissipation makes it impossible for traditional shock-capturing methods to locate the detonation front.To solve these challenges,the proposed method leverages an adaptive multi-resolution representation model to separate the scales of the reaction from those of fluid dynamics,achieving both high-resolution solutions and high efficiency.A level set technique is used to capture the detonation front sharply and reduce errors due to the inaccurate prediction of detonation speed.In order to ensure conservation,a conservative modified finite volume scheme is implemented,and the front transition fluxes are calculated by considering a Riemann problem.A series of numerical examples of stiff detonation simulations are performed to illustrate that the present method can acquire the correct propagation speed and accurately capture the sharp detonation front.Comparative numerical results also validate the approach’s benefits and excellent performance.展开更多
文摘A complete boundary integral formulation for steady compressible inviscid flows governed by nonlinear equations is established by using ρV as variable. Thus, the dimensionality of the problem to be solved is reduced by one and the computational mesh to be generated is needed only on the boundary of the domain.
基金This study was supported by the National Natural Science Foundation of China(Grants 11372168,11772179).
文摘In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,including inviscid LBFS Ⅰ,viscous LBFS Ⅱ,hybrid LBFS Ⅲ and hybrid LBFS Ⅳ.Hybrid LBFS can automatically realize the switch between inviscid LBFS Ⅰ and viscous LBFS Ⅱ through introducing a switch function.The resultant hybrid WENO-LBFS scheme absorbs the advantages of WENO scheme and hybrid LBFS.We investigate the performance of WENO scheme based on four kinds of LBFS systematically.Numerical results indicate that the devopled hybrid WENO-LBFS scheme has high accuracy,high resolution and no oscillations.It can not only accurately calculate smooth solutions,but also can effectively capture contact discontinuities and strong shock waves.
基金supported partly by National Science Foundation of China(10728026)National Basic Research Program of China(2007CB714600).
文摘In this paper,an immersed boundary algorithm is developed by combining the ghost cell method with adaptive tree Cartesian grid method.Furthermore,the proposed method is successfully used to evaluate various inviscid compressible flow with immersed boundary.The extension to three dimensional cases is also achieved.Numerical examples demonstrate the proposed method is effective.
基金Natural Science Foundation of Jiangsu Province(Grant No.BK20191271)the National Numerical Wind Tunnel Project(Grant No.NNW2019ZT2-B28).
文摘This paper presents a robust sharp-interface immersed boundary method for simulating inviscid compressible flows over stationary and moving bodies.The flow field is governed by Euler equations,which are solved by using the open source library OpenFOAM.Discontinuities such as those introduced by shock waves are captured by using Kurganov and Tadmor divergence scheme.Wall-slip boundary conditions are enforced at the boundary of body through reconstructing flow variables at some ghost points.Their values are obtained indirectly by interpolating from their mirror points.A bilinear interpolation is employed to determine the variables at the mirror points from boundary conditions and flow conditions around the boundary.To validate the efficiency and accuracy of this method for simulation of high-speed inviscid compressible flows,four cases have been simulated as follows:supersonic flow over a 15°angle wedge,transonic flow past a stationary airfoil,a piston moving with supersonic velocity in a shock tube and a rigid circular cylinder lift-off from a flat surface triggered by a shock wave.Compared to the exact analytical solutions or the results in literature,good agreement can be achieved.
文摘This paper at first shows the details of finite volume-based lattice Boltzmann method(FV-LBM)for simulation of compressible flows with shock waves.In the FV-LBM,the normal convective flux at the interface of a cell is evaluated by using one-dimensional compressible lattice Boltzmann model,while the tangential flux is calculated using the same way as used in the conventional Euler solvers.The paper then presents a platform to construct one-dimensional compressible lattice Boltzmann model for its use in FV-LBM.The platform is formed from the conservation forms of moments.Under the platform,both the equilibrium distribution functions and lattice velocities can be determined,and therefore,non-free parameter model can be developed.The paper particularly presents three typical non-free parameter models,D1Q3,D1Q4 and D1Q5.The performances of these three models for simulation of compressible flows are investigated by a brief analysis and their application to solve some one-dimensional and two-dimensional test problems.Numerical results showed that D1Q3 model costs the least computation time and D1Q4 and D1Q5 models have the wider application range of Mach number.From the results,it seems that D1Q4 model could be the best choice for the FVLBM simulation of hypersonic flows.
基金the National Natural Science Foundation of China(11771360,12171401)the Natural Science Foundation of Fujian Province of China(2019J02003).Z.P.Xin was supported by Zheng Ge Ru Foundation,Hong Kong RGC Earmarked Research Grants CUHK14305315,CUHK14302819,CUHK14300917,CUHK14302917,CUHK14300819,and Basic and Applied Basic Research Foundation of Guangdong Province(2020B1515310002).
文摘This paper concerns the inviscid,heat conductive and resistive compressible MHD system in a horizontally periodic flat strip domain.The global well-posedness of the problem around an equilibrium with the positive constant density and temperature and a uniform non-horizontal magnetic field is established,and the solution decays to the equilibrium almost exponentially.Our result reveals the strong stabilizing effect of the transversal magnetic field and resistivity as the global well-posedness of compressible inviscid heat-conductive flows in multi-D is unknown.
基金The authors gratefully thank K.Tang and A.Beccantini fromthe Commissariata l’Energie Atomique for having provided the numerical solutions computed with their sevenequation model.The second author would like to particularly acknowledge the support provided by the German Jordanian University through the project SEED-SNRE 7-2014.
文摘A compressible and multiphase flows solver has been developed for the study of liquid/gas flows involving shock waves and strong expansion waves leading to cavitation.This solver has a structure similar to those of the one-fluid Euler solvers,differing from them by the presence of a void ratio transport-equation.The model and the system of equations to be simulated are presented.Results are displayed for shock and expansion tube problems,shock-bubble interaction and underwater explosion.Close agreement with reference solutions,obtained from explicit finite volume approaches,is demonstrated.Different numerical methods are additionally displayed to provide comparable and improved computational efficiency to the model and the system of equations.The overall procedure is therefore very well suited for use in general two-phase fluid flow simulations.
基金the National Natural Science Foundation of China under Grants No.12102052,No.11871113 and No.12171049.
文摘For compressible reactive flows with stiff source terms,a new block-based adaptive multi-resolution method coupled with the adaptive multi-resolution representation model for ZND detonation and a conservative front capturing method based on a level-set technique is presented.When simulating stiff reactive flows,underresolution in space and time can lead to incorrect propagation speeds of discontinuities,and numerical dissipation makes it impossible for traditional shock-capturing methods to locate the detonation front.To solve these challenges,the proposed method leverages an adaptive multi-resolution representation model to separate the scales of the reaction from those of fluid dynamics,achieving both high-resolution solutions and high efficiency.A level set technique is used to capture the detonation front sharply and reduce errors due to the inaccurate prediction of detonation speed.In order to ensure conservation,a conservative modified finite volume scheme is implemented,and the front transition fluxes are calculated by considering a Riemann problem.A series of numerical examples of stiff detonation simulations are performed to illustrate that the present method can acquire the correct propagation speed and accurately capture the sharp detonation front.Comparative numerical results also validate the approach’s benefits and excellent performance.
