CFD based mini- vs. micro-system delineation in elongated bubble flow regime |
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| Institution: | 1. Laboratory of Experimentation and Numerical Simulation in Heat and Mass Transfer, LEMA, Dept. of Mechanical Engineering and Energy, Instituto Politécnico, IPRJ/UERJ, Rua Bonfim, 25, Nova Friburgo, RJ CEP 28624-570, Brazil;2. Laboratory of Nano- and Microfluidics and Microsystems, LabMEMS, Laboratory of Transmission and Technology of Heat, LTTC, Mechanical Engineering Dept. & Nanoengineering Dept. – POLI&COPPE, UFRJ, Universidade Federal do Rio de Janeiro, Cidade Universitária, Cx. Postal 68503, Rio de Janeiro, RJ CEP 21945-970, Brazil;1. Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada;2. Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada;1. Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People''s Republic of China;2. Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People''s Republic of China |
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| Abstract: | Delineation of mini- and micro-scale channels with respect to two-phase flow has been the subject of many research papers. There is no consensus on when the small channel can be characterized as a mini-channel or micro-channel. The idea proposed by this paper is to use the normalized bubble nose radius, liquid film thickness top over bottom ratio, and bubble shape contour, which are found under normal gravity conditions in slug flow through a horizontal adiabatic channel, as the delineation criteria. The input parameters are bubble nose radius and bubble nose velocity as the characteristic length scale and characteristic velocity scale respectively. 3D numerical simulation with ANSYS FLUENT was used to obtain the necessary data. Following CFD practice, a mesh independence study and a numerical model validation against published experimental data were both conducted. Analysis of the numerical simulation results showed that channels with D ⩽ 100 μm can be characterized as a micro-system, while channels with D ⩾ 400 μm belong to mini-systems. The region 200 μm ⩽ D ⩽ 300 μm represents a transition from the micro-scale to mini-scale. |
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| Keywords: | Two-phase flow Mini- vs micro-channel Elongated bubble Liquid film thickness CFD |
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