Three-objective optimization of a staggered herringbone micromixer

Shape optimization of a staggered herringbone micromixer (SHM) was performed using the three-dimensional numerical analysis of fluid flows and mixing of two fluids, surrogate modeling, and a multi-objective genetic algorithm. Two design variables related to dimensions of the grooves, i.e., depth and width, were chosen for optimization. Three performance parameters, i.e., the mixing index at the exit of the micromixer, overall friction factor, and mixing sensitivity, which is the mixing index at a specified axial location in upstream part of the micromixer, were employed as the objective functions. Surrogate modeling was performed for the objective functions using response surface approximation. Multi-objective genetic algorithm was used to find the Pareto-optimal solutions. Representative Pareto-optimal designs were analyzed using numerical analysis and a particle tracking method. The optimization results indicate that wide and deep grooves are desirable to promote faster mixing with a low pressure drop inside the SHM.