Numerical Simulation Of Porous Media Flow In Non-newtonian Fluid Based On Lattice Boltzmann Method

Fluid flow in porous media has become a hot research field,but most of the current research is focused on Newtonian fluid.A growing number of industries involve non-newtonian fluids,including food,petroleum,chemicals,plastics and other fields.Therefore,its flow in porous media also has a common engineering application background,such as the performance optimization of the filled tower in chemical engineering,the purification of groundwater,the mining of mineral resources and the purification of exhaust emissions.It is of great engineering significance to study the flow characteristics of non-newtonian fluids in porous media.Lattice Boltzmann method(LBM),as a mesoscopic analysis method,has many advantages,such as good parallel performance,convenient processing of boundary conditions,and high computational efficiency.In this paper,the analytical model of LBM for porous media flow of non-newtonian fluid is established and its flow law is analyzed.The research content comes from the project of national natural science foundation of China "numerical simulation study of porous media and two-phase flow based on lattice Boltzmann method".Firstly,the flow phenomenon of Newtonian fluid in porous media was studied by LBM based on the seepage model in REV scale.In this model,a force term is added to the evolution equation,and porosity is introduced into the equilibrium distribution function and the force term to reflect the action of porous media on the flow.The flow in the plane Poiseuille flow of Newtonian fluid and the equal-current channel filled with porous media are simulated by computer programming,and the stable velocity field is obtained.On this basis,the flow law of Newtonian fluid is explored,and the flow parameters of porous media and their effects on flow are analyzed.Secondly,the flow of non-newtonian fluid in porous media is studied.In the simulation,the LBM model based on the seepage model is used to solve the generalized navier-stokes equation describing the flow of porous media.The constitutive equation uses the power law model,the deformation rate tensor is calculated by the local method,and the relaxation time is calculated by cyclic iteration.Finally,the flow of power rate fluid in a circular dc channel with equal section filled with porous media is simulated by programming,and the results are compared with the macroscopic numerical simulation results,which show that the results have good accuracy.And the influences of Reynolds number,porosity,power law exponent and Darcy number on the flow are investigated respectively.An axisymmetric flow lattice Boltzmann model of porous media was established,and the effects of Reynolds number and porosity on the flow of porous media in the pipeline were analyzed.The study on the flow of Newtonian fluid and power law fluid in porous media in this paper is not only helpful to the study of porous media flow in engineering,but also provides a theoretical basis for other constitutive models of non-newtonian fluid flow in porous media.