Study On Numerical Simulation And Optimization Of Mixing Performance Of Passive Micromixer At Low Reynolds Number

Microsystem is one of important developing field of modern manufacture technology, and micromixer is a critical part of microsystem, which have attracted more and more attention of researches. In order to increase the speed of designing high efficiency and quick mciromixer, mixing performance of micromixer under different parameters is systematically investigated in this paper.By Fluent, using circulating skill, mixing performance of different property fluid in simple micromixers(SCM), Staggered herringbone micromixers (SHM) and Split-Recombining micromixers(SRM) are simulated . The main conclusions show as following:1) Mixing performance of SCM depends on molecular diffusion at low Re, the bigger diffusion coefficient of fluid and the longer fluid diffusion time is, the lower mixing nonuniform degree is.2) Pressure drop of real microchannels by wet corrosion is linear with fluid Re and is power exponent with cross shape factorη, which means cross shape factor's effect is intenser than Re's.3) As to SHM, the smaller Sc of fluid is, the larger influence of Re on fluidic mixing nonuniform degree is, which indicates that influence of chaotic convection is bigger than that of molecular diffusion. If Re increase up to some extent, fluid mixing will totally rely on chaotic convection.4) As to SRM, fluid molecular diffusion and split-recombining diffusion affect fluid mixing simultaneously; Re has bigger effect on mixing performance of W-SRM compared to T-SRM. In order to improve mixing performance of split-recombine passive micromixer, the split-recombine structure should ensure the direction of two parts of fluid is vertical to each other, which makes one part of fluid hit the other one, at the same time, length of recombining channel should be decreased, which makes sure fluids have statue of hitting.Generally, mixing performance of SHM is greater than that of SCM; when Pe≤50000, mixing performance of SRM is more excellent than that of SHM, with the Pe adding continuously, phenomenon of SHM mixing performance is more superiority than that of W-SRM.