Open Access

ARTICLE

Numerical Simulation of Droplet Generation in Coaxial Microchannels

Zongjun Yin^*, Rong Su, Hui Xu

School of Mechanical Engineering, Anhui Institute of Information Technology, Wuhu, 241100, China

* Corresponding Author: Zongjun Yin. Email:

Fluid Dynamics & Materials Processing 2024, 20(3), 487-504. https://doi.org/10.32604/fdmp.2023.042631

Received 06 June 2023; Accepted 05 September 2023; Issue published 12 January 2024

Abstract

In this study, numerical simulations of the pinching-off phenomena displayed by the dispersed phase in a continuous phase have been conducted using COMSOL Multiphysics (level-set method). Four flow patterns, namely “drop flow”, “jet flow”, “squeeze flow”, and “co-flow”, have been obtained for different flow velocity ratios, channel diameter ratios, density ratios, viscosity ratios, and surface tension. The flow pattern map of two-phase flow in coaxial microchannels has been obtained accordingly, and the associated droplet generation process has been critically discussed considering the related frequency, diameter, and pinch-off length. In particular, it is shown that the larger the flow velocity ratio, the smaller the diameter of generated droplets and the shorter the pinch-off length. The pinch-off length of a droplet is influenced by the channel diameter ratio and density ratio. The changes in viscosity ratio have a negligible influence on the droplet generation pinching frequency. With an increase in surface tension, the frequency of generation and pinch-off length of droplets decrease, but for small surface tension the generation diameter of droplet increases.

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Graphical Abstract

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Keywords

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