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.本研究通过数值模拟分析了被动式圆形非平衡分流-汇合型微混合器（passive circular unbalanced split & recombine micromixer）内部的流体混合过程。求解了连续性方程、纳维-斯托克斯方程与质量扩散方程，并针对纵横比为3.00的工况开展数值模拟。将宽度比（w1/w2）在1.90至2.20范围内设置7种不同取值，且针对每个宽度比取值，分别在雷诺数（Reynolds number）为10、20、40、60与80的5种工况下开展数值模拟。借助流线图、等值线云图等手段对流体混合现象进行阐释，分析了横向平面内二次流的生成机制及其对强化混合效果的贡献。最终采用混合指数（mixing index）对该微混合器的混合性能进行量化表征。