Lattice Boltzmann Method-based Numerical Simulation Research On Microscale Flow

At present,manufacturing technology of the micro-fluidic chip tended to be mature,but the research on the flow behavior in micro-scale channel is not deep. Lattice Boltzmann is a method of meso scale,which can connect the particle behavior of micro-scale to the volume of macro-scale effectively.Compared with the traditional method of computational fluid dynamics,the computational efficiency of Lattice Boltzmann is high,and easy to deal with complex boundary conditions,which has developed into one of the important method of numerical simulation of micro-scale fluid mechanics.While the LB method study has made a lot of progress,there are still a number of shortcomings,such as micro-flow of suspended particulates and the two-way coupling problem of the fluid.In order to promote application of LB methods in micro-flow channel,this article studies circle flow problems in the micro-scale flow channel,suspended particulates movement and the cavity flow phenomena,lays the necessary foundation for future research.The paper first introduced the LB model in detail,and gives disposal of the outside force item.In the case of non-pressure,simulate Poiseuille flow in two-dimensional flow by LB model,the simulation results match well the theoretical solution and verify the correctness of the LB model.Further speaking,it is using the method of LB to study the flow around phenomenon within two-dimensional flow channel.Reynolds number is describing to effect of viscous of similar criteria in fluid mechanics,when the Reynolds number is low,boundary layer separation phenomenon will not happen in the two-dimensional channels in the cylinder,and mediation phenomenon will also not happen in the flat plant flow phenomenon;when the Reynolds number is high,eddy structure will happen in the problem of single cylinder flow,and there is trailing vortex phenomenon in the problem of double cylinder flow,at the same time,The distance between the two columns affects the flow of streams,In addition,in the dual-plate flow problems,the back of each plate appears a whirlpool phenomenon.In this paper,application problem of the LB method in the magnetic fluid and suspension the partly is studied.When particles move in suspension,a single particle is in balance state finally,its velocity and displacement is stable,and when the system exists a number of particles,the particle distribution in the final state is no law,and uniformly distribute in the fluid.By the study,in the process of particles settling,the particle size and density have an impact on the settling velocity,the greater the radius of particle is,the greater the density is,the greater the velocity is,but when the particle speed is same to the speed of solution,the size of particles radius will have an little impact on settling velocity.Finally,this paper researched the cavity flow problem of the magnetic fluid, analyzed velocity distribution in channel,the size of magnetic field affects the speed of fluid,and the stronger the magnetic field is,in the campaign process,the greater the fluctuations is in particle movement.Many conclusions of LB method can be extended to more complex systems in the papers,provide guidance for development and design of micro-fluidic chip.