Mathematical Analysis of a Spiral Passive Micromixer

This research work possesses a mathematical analysis and comparison of mixing performance and flow behavior inside microchannels with different geometries: simple T shape and spiral/helical shape. The flow analysis is carried out using Navier–Stokes equations, and mixing performance of two fluids, namely water and dye, is numerically calculated. The mixing performance is calculated in terms of mixing index or efficiency of mixing. The spiral-shaped mixer generates the formation of mixing-inducing flows even at low Reynolds numbers as compared to a simple T shaped mixer. The circular cross section in the beginning of mixing spiral microchannel increases the interfacial area of the fluid streams by stretching. The proposed spiral microchannel is found to be effective in mixing fluids at wide range of Reynolds numbers, 5, 45, 165, and 350. The proposed mixer is easy to fabricate and offers a wide control for the mixing index based on Reynolds number. The results reveal that mixing in a spiral microchannel is very sensitive to the geometric parameters, showing different behavior at various Reynolds numbers.