Lattice Boltzmann Simulation Of Two Phase Fluids In A Square Cavity

Lattice Boltzmann method (LBM), as a mesoscopic kinetic model, has a lot of advantages, such as the simple and clear evolution process, easy implementation on computers, parallelism in nature, the treatment of the interaction among fluids at the microscopic level and so on. The advantages mentioned above can make LBM be suitable to study large-scale physical problems with complex boundry conditions. Up to now, LBM has attained many successes in many fields, for example, multiphase flows, turbulent flows, large eddy simulation (LES), flows in porous media, micro-scale flows.The single-phase lid-driven cavity flow has been studied widely and used to validate some new numerical methods. The multiphase flow in a square cavity has gained particular attention for its applications in the oil industry, chemical engineering and other fields, However, this problem has not been investigated systematically.In the thesis, the two-phase Poiseuille flow is firstly simulated, then we pay attention to some fundamental problems, for example, the surface force and contact angle. After that, the multiphase flow in the square cavity is studied in detail:the Reynolds (Re) number on the interface length is first investigated through selecting some different Reynolds numbers, the numerical results show that the interface length increases faster with the increase of Re; then, we investigate the effect of the capillary number (Ca) on the interface length, and find that the interface length increases faster with the increase of Ca; in addition, the wettability of the wall is also considered. For superhydrophic surface, the interface length increases at the beginning, then it seems to be a constant. The interface length changes more quickly while the degree of superhydrophic or hydrophobic surface is higher.