Study of mixing in circular unbalanced split & recombine micromixer

In the present work, numerical simulation has been performed to analyze the mixing of fluids inside a passive circular unbalanced split & recombine micromixer. The continuity, Navier-Stokes & mass diffusion equations were solved and numerical simulation were performed for aspect ratios of 3.00. The width ratio (w1/w2) was varied for seven different values between 1.90 & 2.20 and numerical simulations were performed for five different Reynolds numbers (10, 20, 40, 60 & 80) at each value of width ratio. The mixing phenomenon was explained with the help of stream lines plots, contour plots etc. The generation of secondary flows across the transverse plane and their contribution in achieving better mixing has been explained. The mixing performance of the micromixer is quantified with the help of mixing index.