Lattice Boltzmann Simulation On Flow Through Porous Media

The lattice Boltzmann method(LBM) is used to study relevant laws of the fluid flow through porous media. In the first part, the LB model is adopted to numerically investigate the heterogeneous flow in three porous biofilter models. It is found that the Darcy number, Reynolds number and the property of porous media have dominant influence on the flow heterogeneity. The reduction of flow heterogeneity can be effectively established by designing a comparatively low Darcy number and an optimal porosity. However, the reduction of flow heterogeneity can’t be realized effectively by regulating the Reynolds number. In the second part, the thermal LB model is applied to numerically study the effect of temperature on the performance of three porous biofilter models. By performing the non-isothermal boundary condition on the left and right walls, it is found the existence of critical Rayleigh numbers for the thermal porous flow. The numerical results indicate that the property of porous media and the inlet flow condition have great influence on values of the critical Rayleigh number. As the increasing of Darcy number and porosity, the critical Rayleigh numbers will gradually decrease; however, it will steadily increase as the augment of inlet Reynolds number. These two parts are helpful to provide a rational theoretical guidance for the optimized design of biofilter.In the last part, the thermal LB model is used to simulate the process of natural convection and heat transfer in the porous cavity. The evolution process of steady or unsteady vortice is also analyzed. The simulation results show that the fluid will raise steady vortex under the small Rayleigh number, and the large Rayleigh number will induce the formation of unsteady vortex. It is demonstrated that the porosity and Darcy number have dominant influence on the pattern of vortex, and the critical Rayleigh number of the steady vortex decrease when the porosity and Darcy number increase.