Simulation Study On The Formation And Breakup Mechanism Of Droplets In Microchannels

With the rapid development of microfluidic chip, which is not only limited in analytical chemistry and has been expanded to the biology, medicine, pharmacy,material science, physics and other disciplines, microfluidic has become a newly emerged branch of science and the formation and manipulation of droplets are the foundation, but the relevant research need to be further. In order to achieve the precise controlling of droplets, this paper studies the droplets formation and manipulation in micro-channel and related factor in droplet formation and breakup process, describes the influence of surface tension and viscous force, which is critical to microfluidics.Firstly, the paper summarizes the research status, expounds the theories of two phase flow in micro-channel, analyzes the relevant dimensionless number, the surface wetting property and the contact angle in the droplet formation and point out current problem and development trend.Secondly, a T-shape micro-channel model is established by using COMSOL and Level set interface tracking method to simulate droplet formation, study the influence of changing continuous phase flow rate and viscosity in droplet formation to seek for general rules, then compare with Graff's experiment to convinces the result is correct.Thirdly, a crossing 3D model is established to perform droplet formation,combined with present study result, calculating the dimensionless number to find out the main factor in crossing micro-channel, looking for the difference compared with T shape micro-channel, study the influence of continuous phase flow rate and viscosity in droplet formation, at last change the contact angle from 135° to 30° and find the find the mechanism of droplet formation is changed.Finally, base on the existing research, study droplet breakup without gap in Y shape channel, observation the interface's transformation and analysis the reason, then study the influence of bifurcation angle in breakup, through data simulation,analysis force in different condition.