Multi-objective optimization of expansion-contraction micromixer using response surface methodology: A comprehensive study

This study provides a comprehensive analysis of the optimization of micromixers, highlighting their critical role in improving the effectiveness of chemical reactions and fluid mixing processes at a small scale. Employing OpenFOAM, we optimized the geometry of a micromixer comprised of multiple expansion-contraction segments across a Reynolds number range from 0.1 to 100. We established three design variables, P1, P2, and P3, to modify the geometry of each contraction-expansion segment to maximize the overall performance of the micromixer. Our experimental design utilized the optimal space-filling method, followed by the application of the genetic aggregation method to the generated sample to yield response surfaces. Two distinct optimization strategies were implemented following the verification of the response surfaces' accuracy. The first focused on maximizing the mixing index, while the second aimed to increase the mixing index and reduce the pressure difference simultaneously. A subsequent sensitivity analysis revealed significant relationships between the design variables and objective parameters. Key findings include achieving maximum MI increases of 26.26 % and 23.06 % at Re values of 10 and 100, respectively, and the role of recirculation zones and chaotic convection in enhancing mixing, especially at Re = 100. Furthermore, a comparative analysis with other micromixer optimization studies demonstrated the superiority of the present study, particularly in reducing pressure difference, thereby enhancing overall mixer performance.