多孔介质内流体流动的格子Boltzmann模拟

采用格子Boltzmann方法模拟多孔介质内的流动过程，通过预测渗透率，比较了单松弛模型、多松弛模型和熵格子模型在多孔介质计算中的优劣，为研究多松弛模型中各自由参数的影响，选择了12种组合进行模拟，此外，还将大涡模拟与格子Boltzmann方法相结合模拟了多孔介质内高Reynolds数下的流动及流型的转变。结果表明：单松弛模型和熵格子模型预测的渗透率随黏度逐渐增大，而多松弛模型得到的结果随黏度变化很小，另外，多松弛模型中不同松弛参数的组合对结果有较大的影响，通过比较推荐了模拟多孔介质时的最佳组合，计算结果与经验公式吻合较好。大涡模拟与多松弛模型结合较好地预测了多孔介质内流型的转变，Reynolds数越大，多孔介质内的涡越多，并且变大。

Lattice Boltzmann simulations for fluid flow through porous media

The flow through porous media was numerically simulated using lattice Boltzmann method (LBM). By predicting permeability, the capability and accuracy for simulating flow through porous media were evaluated for various of lattice models: lattice Bhatnagar-Gross-Krook (LBGK) or called single relaxation time (SRT), multiple relaxation time (MRT) and entropic lattice Boltzmann method (ELBM). In order to research the influences of each free parameter to permeability in the MRT model, a total of 12 kinds of combinations were selected. Furthermore, the large eddy simulation (LES) and LBM were coupled to simulate flow through porous media at high Reynolds number and the transformation of flow patterns. The results indicate that permeability increased with viscosity predicted by LBGK and ELBM, but there are little variation for permeability predicted by MRT. In addition, the different combinations of relaxation parameters have a greater impact to the permeability, and an optimum combination is recommended for simulating flow through porous media. Simulated results are in quantitatively agreement with the empirical formula. The transformations of flow patterns are successfully predicted in porous media using LES-MRT. Higher Reynolds number, more and bigger vortexes in porous media are observed.