多孔介质复合方腔双扩散混合对流LBM模拟

LBM Simulation of Double Diffusive Mixed Convection in a Porous Medium Composite Cavity

基于CLBGK模型,通过引入浓度分布函数,利用格子Boltzmann方法对顶盖驱动的复合方腔内的双扩散混合对流现象进行了研究,复合方腔由多孔介质区域和纯流体空间组成.在Richardson(理查德森)数Ri=1.0,Lewis(路易斯)数Le=2.0,Grashof(格拉晓夫)数Gr=10~4和Prandtl(普朗特)数Pr=0.7时,分析了孔隙尺度下多孔介质层不同位置及浮升力比(-5.0≤N≤5.0)对复合方腔双扩散混合对流的影响.给出了浮升力比N及多孔介质层位置影响下的高温高浓度壁面上的平均Nusselt(努赛尔)数Nu_(av)、平均Sherwood(舍伍德)数Sh_(av)及当地Nusselt数Nu_(local)和Sherwood数Sh_(local)的分布规律.

Based on the coupled lattice Bhatnagar-Gross-Krook （CLBGK） model, the lattice Boltzmann method was used and the concentration distribution function was introduced to in- vestigate the double diffusive mixed convection in a lid-driven composite cavity composed of a porous medium layer and the rest space full of pure fluid. At Ri = 1.0, Le = 2.0, Gr = 104, Pr = 0. 7, 6 = 0.7, the influences of the porous layer locations and the buoyancy ratios （ - 5.0 ≤ N 5.0） on the double diffusive mixed convection in the porous medium composite cavity were studied at the pore scale. Results presented in the distribution diagrams of local and average Nusselt and Sherwood numbers at the high temperature and concentration wall of the cavity show the mixed convection rule.