| In recent years, along with some emerging and rapid development technologies, such as microfluidics, the microscale flow and mass transfer studies have already become more and more important. In addition to basic theoretical research and experiment, the numerical simulation is also an important tool. The most commonly used fluid simulation method is Computational Fluid Dynamics (CFD) which is based on the Navier-Stokes Equation. However, the NSE requires to meet the continuum theory cause its further application to be restricted. Molecular dynamics (MD) method is recognized as the most accurate simulation method, but its huge amount of computation is difficult to accept in conventional experimental conditions. Therefore, we need a new method which both can analyze the discontinuous fluid flow and inexpensive, and the mesoscopic method which based on statistical mechanics is one of the best options. In recent20years, lattice Boltzmann method (LBM) as a novel method uses microscopic model to simulate the macroscopic behavior of fluid has been development very well. Compare with traditional algorithms, the evolution equation of LBM is simple, easy to implement parallel computing and can handle complex boundary issues and others advantages. In macro-scale, LBM for complex flow simulation and modeling has made important progress, but for the microscale flow, LBM is still in its infancy.This paper focuses on simulation of micro flows. First, the basic process from Boltzmann equation to lattice Boltzmann equation has been introduced, then we through several typical examples show the accuracy of LBM, and finally LBM is applied to the microscale flow, compared several common relationship of τ-Kn and construct a velocity slip boundary condition scheme. In addition, we also derive the hydromechanics equations with the basic assumptions of microscale flow, then as the basis for design a passive micromixer, and introduce the mixing intensity factor to evaluation the mixing quality. |
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