Impingement and mixing dynamics of micro-droplets on a solid surface

GN Yi and ZQ Cai and ZM Gao and JJ Derksen, CHINESE JOURNAL OF CHEMICAL ENGINEERING, 52, 66-77 (2022).

DOI: 10.1016/j.cjche.2021.11.001

The hydrodynamics and mixing during the nonaxisymmetry impingement of a micro-droplet and a ses-sile droplet of the same fluid are investigated by many-body dissipative particle dynamics (MDPD) sim-ulation. In this work, the range of the impingement angle (0i) between the impinging droplet and the sessile droplet is 0 degrees-60 degrees and the contact angle is set as 45 degrees or 124 degrees. The droplets impingement and mixing behavior is analyzed based on the droplet internal flow field, the concentration distribution and the time scale of the decay of the kinetic energy of the impinging droplet. The dimensionless total mixing time (rm) is calculated by a modified mixing function. With the Weber number (We) ranging from 5.65 to 22.7 and the Ohnesorge number (Oh) ranging from 0.136 to 0.214, we find rm hardly changes with We and Oh. Whereas, 0i and surface wettability are found to have a significant effect on rm. We find that 0i has no clear effect on rm on a hydrophobic surface, while on the hydrophilic surface, rm increase with the 0i. Thus, reducing the impinging angle is a valid method to shorten the rm.(c) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

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