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

Yoshimura, Mitsuo; Shimoyama, Koji; Misaka, Takashi; Obayashi, Shigeru

doi:10.1007/s10404-019-2201-6

Cited by 28 publications

(7 citation statements)

References 60 publications

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“…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.…”

Section: Design Variables Via Graph Theorymentioning

confidence: 99%

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

Shimoyama¹,

Komiya²

2022

Struct Multidisc Optim

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Additive manufacturing (AM) has an affinity with topology optimization to think of various designs with complex structures. Hence, this paper aims to optimize the design of a lattice-structured heat sink, which can be manufactured by AM. The design objectives are to maximize the thermal performance of convective heat transfer in natural convection simulated by computational fluid dynamics (CFD) and to minimize the material cost required for AM process at the same time. The lattice structure is represented as a node/edge system via graph theory with a moderate number of design variables. Bayesian optimization, which employs the non-dominated sorting genetic algorithm II and the Kriging surrogate model, is conducted to search for better designs with the minimum CFD cost. The present topology optimization successfully finds better lattice-structured heat sink designs than a reference fin-structured design regarding thermal performance and material cost. Also, several optimized lattice-structured designs outperform reference pin-fin-structured designs regarding thermal performance though the pin-fin structure is still advantageous for a material cost-oriented design. This paper also discusses the flow mechanism observed in the heat sink to explain how the optimized heat sink structure satisfies the competing design objectives simultaneously.

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Section: Design Variables Via Graph Theorymentioning

confidence: 99%

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

Shimoyama¹,

Komiya²

2022

Struct Multidisc Optim

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“…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.…”

Section: Introductionmentioning

confidence: 99%

Optimal Combination of Mixing Units Using the Design of Experiments Method

Juraeva

Kang

2021

Micromachines

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A passive micromixer was designed by combining two mixing units: the cross-channel split and recombined (CC-SAR) and a mixing cell with baffles (MC-B). The passive micromixer was comprised of eight mixing slots that corresponded to four combination units; two mixing slots were grouped as one combination unit. The combination of the two mixing units was based on four combination schemes: (A) first mixing unit, (B) first combination unit, (C) first combination module, and (D) second combination module. The statistical significance of the four combination schemes was analyzed using analysis of variance (ANOVA) in terms of the degree of mixing (DOM) and mixing energy cost (MEC). The DOM and MEC were simulated numerically for three Reynolds numbers (Re = 0.5, 2, and 50), representing three mixing regimes. The combination scheme (B), using different mixing units in the first two mixing slots, was significant for Re = 2 and 50. The four combination schemes had little effect on the mixing performance of a passive micromixer operating in the mixing regime of molecular dominance. The combination scheme (B) was generalized to arbitrary mixing slots, and its significance was analyzed for Re = 2 and 50. The general combination scheme meant two different mixing units in two consecutive mixing slots. The numerical simulation results showed that the general combination scheme was statistically significant in the first three combination units for Re = 2, and significant in the first two combination units for Re = 50. The combined micromixer based on the general combination scheme throughout the entire micromixer showed the best mixing performance over a wide range of Reynolds numbers, compared to other micromixers that did not adopt completely the general combination scheme. The most significant enhancement due to the general combination scheme was observed in the transition mixing scheme and was negligible in the molecular dominance scheme. The combination order was less significant after three combination units.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Fatima

Shakaib

Memon

2021

Theor Found Chem Eng

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This work includes a 3D computational fluid dynamics study on rectangular-shaped micromixers. Initially, T-shaped micromixer types are considered with various width/height ratios for the inlet and the outlet channels and the results are presented in terms of velocity profiles, mass fraction distribution, pressure drop, mixing efficiency and mixing effectiveness. The findings show that the mixers with an outlet channel aspect ratio (width to height ratio) of 2-2.5 yields better mixing performance. The flow separation at the entrance of the mixing channel leads to formation of recirculation zones which promotes mixing. The effect of confluence angle is also examined for a few aspect ratios. The comparison of mixing parameters indicates that large confluence angles are suitable for the micromixing devices.

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

Cited by 28 publications

References 60 publications

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

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

Optimal Combination of Mixing Units Using the Design of Experiments Method

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

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