考虑双向耦合效应的格子Boltzmann气固两相湍流模型

在流体粒子概率密度函数输运方程中考虑颗粒对流体的反作用力,发展了考虑双向耦合效应的LB气固两相流模型,引入Smagorinsky亚格子模型模拟高雷诺数气相流场.对经典后台阶气固两相流动进行模拟,气相和颗粒相速度分布与实验结果进行比较,发现考虑双向耦合效应的LB气固两相流模型结果明显优于单向耦合结果.进一步研究不同惯性颗粒在流场中的弥散特性,小颗粒(St~O(0.1))对流体的跟随性较好,在流场中分布较为均匀;而St~O(1)的颗粒难被流场涡卷吸进入涡内,呈现倾向性弥散现象;大颗粒(St~O(10))由于自身惯性进入流场涡,在流场中分布较为均匀.

Two-way Coupling Lattice Boltzmann Model for Gas-Particle Turbulent Flows

An LB-based gas-solid two-phase model with two-way coupling is developed considering feedback forcing of particles in evolution equation of fluid particles. Smagorinsky subgrid model is also introduced in simulation of flow field with high Reynolds numbers. Classic particle-laden flow over a backward facing step is simulated and velocity profiles of gas phase and particles (considering one-way coupling and two-way coupling respectively) are compared with experimental results. The results of two-way coupling LB model are obviously better than these of one-way coupling LB model. Furthermore, preferential concentration of particles with different Stokes numbers (St) is investigated. It is found that small particles (St~0(0.1)) show better following behaviors with gas phase and are uniformly distributed in the flow field. Particles with moderate Stokes numbers (St~0(1)) are hard to be entrained into the vortex and show strong preferential concentration. On the other hand, large particles (St~0(10)) can enter into the vortex because of great inertial and are distributed more uniformly in flow field.