Numerical Investigation on a Chaotic Passive Micromixer Based on Square Chambers Connected with Different Channel Shapes for Enhancing the Mixing Process

In this work, passive micromixers that consist of square mixing chambers symmetrically placed along the length of the mixer are investigated for the mixing of miscible fluids. The governing equation of Navier–Stokes and the convection–diffusion equation were resolved using the finite element approach, which is implemented in the COMSOL 6.1 software to simulate and evaluate the effectiveness of the mixers. Different design configurations of micromixers are evaluated using three key performance parameters, including the mixing index, pressure drop, and mixing energy cost, to analyze three distinct channel types of curved, square-wave, and zigzag across a wide range of Reynolds numbers, between 0.1 and 45. The study also investigated the behavior of diffusion and chaotic advection, the results showed as Reynolds numbers increase, the mixing index exhibits an initial decrease followed by an increase. Remarkably, all micromixers reach a great mixing performance of 99% at a low Reynolds number of 45. This complete mixing is accompanied by variations in pressure drop values, where the SCC mixer has a smaller pressure drop compared to the SCS-W and SCZ mixers, with decreases of 74.26 and 30.70%, respectively. Comparing the suggested mixer to previously published micromixers, it also has a more compact design and an easier manufacturing procedure.