Concave wall-based mixing chambers and convex wall-based constriction channel micromixers

Abstract

ABSTRACT Micromixers with concave wall-based mixing chambers and convex wall-based constriction channel are studied. The effect of shape and aspect ratio of the obstacle on mixing performance was investigated for the Reynolds number in the range of 0.1–75 using Computational Fluid Dynamics (CFD). The micromixers showed interesting mixing dynamics and flow features in respect of two flow regimes identified for the present study. The first flow regime is for the Reynolds number in the range 0.1 < Re < 5 wherein diffusion-dominated mixing was observed and the second flow regime is for the Reynolds number in the range 5 < Re ≤ 75 wherein convection-dominated mixing was observed. The simulation results reveal that the rectangular obstacle-based micromixer gives mixing index MI ≥ 0.90 at the Re ≥ 30 in all cases of aspect ratio and it is highest compared to triangular obstacle-based and teardrop obstacle-based micromixers. Further, in respect of pressure drop, teardrop obstacle-based micromixer showed less pressure drop. Both mixing index and pressure drop increase with increase in aspect ratio of the obstacle. The proposed micromixers are simple in design which make them best candidates for environmental and clinical analysis or diagnostic systems.