Multi-relaxation time lattice Boltzmann method is employed to study the later stages of Rayleigh Taylor instabilities. A heavy fluid is placed over an immiscible lighter fluid in an unstable equilibrium. Various initi...Multi-relaxation time lattice Boltzmann method is employed to study the later stages of Rayleigh Taylor instabilities. A heavy fluid is placed over an immiscible lighter fluid in an unstable equilibrium. Various initial disturbances are used to initiate the flow. The D2Q9 lattice arrangement is employed on the computational domain. The density distribution function is determined for both fluids, and a coloring function is used to highlight the two fluids. Interactive forces and body forces are modelled by using the Shah and Chert model. Three different initial disturbances are studied, and their late stages are examined. The classic mushroom structure can be seen on all three cases. Distortions of the mushroom structures are seen due to the effects of the boundary and the influence of the initial disturbance.展开更多
The aquatic vegetation can significantly affect the flow structure,the sediment transport,the bed scour and the water quality in rivers,lakes,reservoirs and open channels.In this study,the lattice Boltzmann method(LBM...The aquatic vegetation can significantly affect the flow structure,the sediment transport,the bed scour and the water quality in rivers,lakes,reservoirs and open channels.In this study,the lattice Boltzmann method(LBM)is applied in the two-dimensional numerical simulation of the flow structure in a flume with rigid vegetation.A multi-relaxation time model is applied to improve the stability of the numerical scheme for flows with a high Reynolds number.The vegetation induced drag force is added in the lattice Boltzmann equation model in order to improve the simulation accuracy and an algorithm of the multi-relaxation time is developed.Numerical simulations are performed for a wide range of flow and vegetation conditions and are validated by comparing with the laboratory experiments.Analysis of the simulated and experimentally measured flow Helds shows that the numerical simulation can satisfactorily reproduce the laboratory experiments,indicating that the proposed lattice Boltzmann model enjoys a high accuracy for simulating the flow-vegetation interaction in open channels.展开更多
文摘Multi-relaxation time lattice Boltzmann method is employed to study the later stages of Rayleigh Taylor instabilities. A heavy fluid is placed over an immiscible lighter fluid in an unstable equilibrium. Various initial disturbances are used to initiate the flow. The D2Q9 lattice arrangement is employed on the computational domain. The density distribution function is determined for both fluids, and a coloring function is used to highlight the two fluids. Interactive forces and body forces are modelled by using the Shah and Chert model. Three different initial disturbances are studied, and their late stages are examined. The classic mushroom structure can be seen on all three cases. Distortions of the mushroom structures are seen due to the effects of the boundary and the influence of the initial disturbance.
基金Supported by the National Natural Science Foundation of China(Grant No.11861003,11761005).
文摘The aquatic vegetation can significantly affect the flow structure,the sediment transport,the bed scour and the water quality in rivers,lakes,reservoirs and open channels.In this study,the lattice Boltzmann method(LBM)is applied in the two-dimensional numerical simulation of the flow structure in a flume with rigid vegetation.A multi-relaxation time model is applied to improve the stability of the numerical scheme for flows with a high Reynolds number.The vegetation induced drag force is added in the lattice Boltzmann equation model in order to improve the simulation accuracy and an algorithm of the multi-relaxation time is developed.Numerical simulations are performed for a wide range of flow and vegetation conditions and are validated by comparing with the laboratory experiments.Analysis of the simulated and experimentally measured flow Helds shows that the numerical simulation can satisfactorily reproduce the laboratory experiments,indicating that the proposed lattice Boltzmann model enjoys a high accuracy for simulating the flow-vegetation interaction in open channels.
