Simulation Of T-type Micromixer Based On Lattice Boltzmann Method

Micro electro mechanical systems (MEMS) is a tiny system based on integrated circuit technology, it merges the electronic components and mechanical components in one. As an important component of MEMS, the micromixer has been paid more and more attention at present. Therefore, studies of the microscale flow and liquid mixture become increasingly important. The research methods of physical system can be divided into theoretical study, experimental study and numerical simulation, with the rapid development of computer technology, and numerical simulation technology gets more and more attention and extensive application. Lattice Boltzmann Method as a brand new mesoscopic simulation method develops rapidly in nearly20years. LBM has made important progress in the simulation of micro fluid flow and modeling, because it can not only analysis discontinuous flow field, but also save the amount of calculation.This article simulated the fluid mixed problem of micromixer based on LBM. First, the article introduces the basic theory of LBM, deduces Boltzmann equation in detail, and introduces some of the basic LBM models and boundary treatment methods. Then, it verifies the feasibility and accuracy of LBM by the simulation of three typical examples in hydrodynamics, and offers the mix-index σ to distinguish the mixing effect of the mixture. At last, LBM is applied to the simulation of fluid mixing of micromixer. The article numerically simulates the simple T-sensor and the rib-type micromixer, and draws the mix curve of different influence factors. For the simple T-sensor, the article gets the following conclusions:the smaller the inlet velocity is, the better the mixing effect is; the smaller the width of mixing channel is, the better the mixing effect is, but the mix-index changes very little; as collision coefficient increases, the fluid spreads faster, the mixing effect gets better; the greater the viscosity coefficient is, the worse the mixing effect is. For the rib-type micromixer, the mixing effect at first get worse and then get better as the inlet velocity decreases; the collision coefficient almost has no effect on the mixing effect of high-speed conditions, but for low-speed conditions the effect is obvious; the greater the length of the inner rib is, the better the mixing effect is; the greater the cycle length is, the worse the mixing effect is, but the changes are very little. Finally, the mixed performance of the two micromixers are compared under different inlet velocity conditions, the result is that the rib-type micromixer is much better than the simple T-sensor.