Unsteady flow mixing effect in bionic micro-flow channel

Micro-mixers are studied extensively due to their high mixing efficiency. A periodic flow variation at the channel entrance will be used to drive fluids in this study to achieve a mixing effect. Numerical analysis is used and verified by experiment in the study to identify the group of operating factors, such as Reynolds number Re, the driving phase difference θ and the driving frequency ratio Fr, needed for the fluid to achieve the best mixing result for a bionic micro-mixer. It is found in this study that the mixing efficiency is related to the velocity period distribution; the more even the velocity period distribution becomes, the better the mixing efficiency and the best group of operating factors is found (Re₂ = 1, Rer = 0.85, Fr = 1, F ₂ = 50 Hz, I/A_m = 1, θ = 3/4 π). Furthermore, a larger aspect ratio results in a better mixing efficiency. The influence of wall-effect on the flow mixing decreases with AR. It is found that there exists an optimal mixing efficiency at aspect ratio AR = 10. These research results could be used to improve the design of a bionic micro-mixer.