Droplet impact: Viscosity and wettability effects on splashing

被引:114
作者
Almohammadi, H. [1 ]
Amirfazli, A. [1 ]
机构
[1] York Univ, Dept Mech Engn, Toronto, ON M3J 1P3, Canada
基金
加拿大自然科学与工程研究理事会;
关键词
Droplet splashing; Surface wettability; Liquid viscosity; Droplet velocity; Liquid surface tension; COLLISIONS; THRESHOLD;
D O I
10.1016/j.jcis.2019.05.101
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Hypotheses: The wettability of a surface affects the splashing behavior of a droplet upon impact onto a surface only when surface exhibits either a very high or a very low contact angle. Viscosity affects the splashing threshold in a non-monotony way. Experiments: To examine the roles of drop viscosity and surface wettability on splashing, a wide range of liquid viscosities (1-100 cSt), surface wettabilities (from hydrophilic to hydrophobic), drop velocities (0.5-3.3 m/s), and liquid surface tensions (similar to 20 and 70 mN/m) were examined. High speed imaging was used. Findings: Wettability affects the splashing threshold at very extreme limits of the wettability i.e. at very high or very low contact angle values; however, the wettability effect is less prominent on spreading-splashing regime map. For drops of any surface tension impacting surfaces with any wettability, an increase in viscosity (up to similar to 5 cSt or Reynolds number of 2000) promotes splashing; whereas using liquids with viscosities larger than 5 cSt, suppress splashing. We explained such behaviors using evolution of the lamella rim, dynamic contact angle, and velocity of the expanding lamella. Finally, to predict the splashing, we developed a general empirical relationship which explains all of ours, and previously reported data. (C) 2019 Elsevier Inc. All rights reserved.
引用
收藏
页码:22 / 30
页数:9
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