Optimization of passive grooved micromixers based on genetic algorithm and graph theory

Abstract

This paper proposes a novel approach for fluid topology optimization using genetic algorithm. In this study, the enhancement of mixing in the passive micromixers is considered. The efficient mixing is achieved by the grooves attached on the bottom of the microchannel and the optimal configuration of grooves is investigated. The grooves are represented based on the graph theory. The mixing performance is analyzed by a CFD solver and the exploration by genetic algorithm is assisted by the Kriging model to reduce the computational cost. The characteristics of the convex and the concave grooves are compared. To balance the global exploration and the reasonable computational cost, this paper investigates three cases with the convex grooves subject to constraint that differs in handling of design variables. In each case, genetic algorithm finds several local optima since the objective function is a multi-modal function, and these optima reveal the specific characteristic for efficient mixing. Moreover, this paper optimizes the micromixer with the concave grooves and reveals the different properties of the mixing. Finally, to guarantee the obtained solutions competitive, the sensitivity analysis is performed to the best solution in each case.

Multi-objective Bayesian topology optimization of a lattice-structured heat sink in natural convection

“…The present topology optimization treats each effective entry of the adjacent matrix as the ith design variable x i ( i = 1, 2, … , 68 ). Each design variable is defined in the range of 0 ≤ x i ≤ 1 , such that the corresponding edge is absent if 0 ≤ x i ≤ 0.2 and present if 0.2 < x i ≤ 1 according to Yoshimura et al (2019), who used the graph theory to optimize the groove structure of a flow micromixer. The present design variables need to be continuous for a surrogate model used in Bayesian optimization.…”

Optimal Combination of Mixing Units Using the Design of Experiments Method

“…For example, Hossain et al [ 19 ] optimized a micromixer with staggered herringbone grooves on the top and bottom walls using the mixing index and friction factor as objective functions. Yoshimura et al [ 20 ] used a topology optimization method with a surrogate-assisted genetic algorithm and applied it to a staggered herringbone micromixer. They evaluated how the combination of grooves with different geometric aspects and the number of grooves affected the mixing performance.…”

Effect of Channel Aspect Ratio and Inclination Angle on Flow and Mixing Performance of a Microdevice—A CFD Study

“…Based on the driving force for mixing, the micromixers can be of an active or a passive type. The advantages of passive type mixers are that their fabrication is relatively simple and they do not require any external means for moving or agitating the fluids [6,10,11]. In passive mixers, laminar flow conditions usually prevail and the molecular diffusion, in addition to the mass convection, is an important mechanism that governs mixing.…”