Mixing performance of a planar micromixer with circular chambers and crossing constriction channels

A planar micromixer design with circular mixing chambers and two constriction channels crossing each other to connect adjacent mixing chambers is proposed in this work. The mixing performance of this micromixer is analyzed numerically, and compared to three other planar micromixers (with circular chambers but with a single constriction channel). Analyses of flow fields and mixing are performed using three-dimensional Navier-Stokes equations for a wide range of Reynolds numbers from 0.1 to 100, with a fixed ratio of the width of the constriction channel to the diameter of the circular chamber (1/8). Mixing is evaluated by calculating a mixing index based on the variance of the mass fraction. The proposed micromixer shows excellent mixing performance in the low Reynolds number range in which diffusion dominates the mixing, but shows the worst performance for Reynolds numbers greater than 50 among the four micromixers tested in this work. The proposed micromixer shows a much lower pressure drop than the other micromixers, especially at higher Reynolds numbers. Thus, the proposed micromixer is recommended for use with Reynolds numbers of less than 10.