A MULTI-BLOCK LATTICE BOLTZMANN METHOD FOR SIMULATING FLUID FLOW THROUGH POROUS MEDIA

摘要

The lattice Boltzmann method (LBM) often employs uniform lattices, which makes it less efficient to perform flow simulations when there is a need for high resolution near the body and/or there is far-field boundary. This paper describes the principle of the multi-block LBM, which can control the coarseness and fineness of grids according to the zone spatial scale. A special treatment of the solid region within the flow field was adopted, so that the highly irregular solid matrix of the porous media could be simulated. The developed code was first validated by the simulations of flow in a lid-driven cavity with Re=100. Good agreement with the benchmark numerical data was obtained. Then the developed method was adopted to predict the flow field of a 2-D channel flow with which a porous media zone existed. For the comparison purpose, a uniformly distributed grid system was also adopted. The results demonstrate that the multi-block LBM accelerates the convergence rate and improve the efficiency of computation and has great advantage in simulating the fluid flow in complicate structures, such as porous media. In the paper, the details of the predicted flow fields are presented.