基于LBM的多孔介质/流体交界面滑移效应细观研究

Study of Slip Effect on Porous Medium and Fluid Interface by Lattice Boltzmann Method

本文采用格子Boltzmann方法对真实多孔介质复合腔体内的自然对流进行了研究,分析了在不同瑞利数Ra、多孔介质厚度δ和高度Y条件下交界面处的滑移效应的变化规律。利用X-CT技术对真实多孔介质材料进行断层扫描,通过Matlab对图片进行处理并导入格子Boltzmann模型中进行求解。计算结果表明:当0.1<Y<0.9,复合腔体交界面速度滑移系数α和应力跳跃系数β随高度Y基本保持不变,而在靠近上下壁面时(Y<0.1和Y>0.9)变化明显;在一定的高度处,α和β均随Ra数发生缓慢变化;多孔介质的厚度δ对α和β影响较小。

The model on natural convection in a cavity partially filled with an actual porous layer was studied and solved numerically by lattice Boltzmann method.The slip effect at the porous/fluid interface was analyzed under different Ra number,height and thickness of the porous medium conditions.The images of real porous structure obtained by X-ray computed tomography technique and processed by Matlab were imported into the lattice Boltzmann model for solving.The numerical results showed that the velocity slip α and stress jump coefficient β would be almost constant with different height（0.1 Y 0.9）,but they will change significantly（Y 0.1 and Y 0.9）;at a certain height,α and β will reduce gradually with increasing Ra number,but variation with thickness is not obvious.