基于孔隙尺度的方腔内多孔介质融化模拟研究

摘要

由于单松弛（ LBGK）格子Boltzmann模型在用反弹格式处理无滑移边界时存在缺陷。基于孔隙尺度，采用多松弛（ MRT）格子Boltzmann模型研究封闭方腔内多孔介质的自然对流融化过程，其中，通过焓方法考虑相变潜热。分析了Rayleigh数和Prandtl数对融化的影响。结果表明：采用的多松弛模型能很好的预测导热和对流融化过程；多孔介质的导热融化界面不再与垂直壁面平行，自然对流融化界面呈现不规则形状；Rayleigh数和Prandtl数对多孔介质的融化有较大影响。%When a bounce⁃back scheme is used to handle no⁃slip boundary conditions, the lattice Bhatnagar⁃Gross⁃Krook ( LBGK) model in lattice Boltzmann method ( LBM) will result in viscosity⁃dependence of boundary locations. So in this paper, the multiple relaxation time ( MRT) model was chosen to research the naturally convec⁃ted melting process of porous media in a closed square cavity based on the pore scale. In particular, the enthalpy⁃based method was used to simulate solid⁃liquid phase change. The effects of Rayleigh and Prandtl numbers on melt⁃ing were also analyzed. The results indicate that the MRT model can well predict conduction⁃dominated and convec⁃tion⁃dominated melting. The solid⁃liquid interface is no longer parallel to vertical walls for conduction melting of porous media. The interface appears irregular shapes in the natural convection⁃dominated melting of porous media. The Rayleigh and Prandtl numbers have larger influence on the melting of porous media.