Yeganehdoust Firoozeh, Amer Adham, Sharifi Navid, Karimfazli Ida, Dolatabadi Ali
Department of Mechanical, Industrial, and Aerospace Engineering, Concordia University, Montreal, Quebec H3G 1M8, Canada.
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada.
Langmuir. 2021 May 25;37(20):6278-6291. doi: 10.1021/acs.langmuir.1c00726. Epub 2021 May 12.
The focus of this study is to investigate and compare the behavior of a droplet on superhydrophobic (SHS) and slippery lubricant impregnated (SLIPS) surfaces under the effect of air shear flow. In this regard, both experimental and numerical analyses have been conducted to compare their performance on droplet mobility under different air speeds. Two different lubricants have been utilized to scrutinize their effect on droplet movement. The numerical simulations have been performed based on the volume of fluid method coupled with the large eddy simulation turbulent model in conjunction with the dynamic contact angle method in addition to a model that can represent the effect of lubricants on slippery surfaces. The numerical simulations are compared with the experimental study in order to shed light on the underlying mechanisms. The results showed that under the same conditions, the critical velocity for droplet movement on the superhydrophobic surfaces is lower than that on the slippery lubricant impregnated surfaces due to the smaller droplet base diameter and the larger contact angle. The hydrodynamics of droplet mobility on superhydrophobic surfaces exhibits a rolling behavior while for the slippery lubricant impregnated surfaces a combination of rolling and sliding is observed. Beyond the critical airflow speed, a complete droplet shedding on all surfaces occurs. The wetting length and position of the droplet on superhydrophobic and slippery surfaces have been measured. On slippery surfaces, the speed of droplets is greatly affected by the lubricant properties while similar behavior in the wetting lengths is observed.
本研究的重点是研究和比较在空气剪切流作用下，液滴在超疏水（SHS）表面和光滑润滑剂浸渍（SLIPS）表面上的行为。在这方面，已经进行了实验和数值分析，以比较它们在不同风速下对液滴迁移率的性能。使用了两种不同的润滑剂来研究它们对液滴运动的影响。除了一个可以表示润滑剂对光滑表面影响的模型外，还基于流体体积法结合大涡模拟湍流模型以及动态接触角法进行了数值模拟。将数值模拟与实验研究进行比较，以阐明潜在的机制。结果表明，在相同条件下，由于液滴底部直径较小和接触角较大，超疏水表面上液滴运动的临界速度低于光滑润滑剂浸渍表面上的临界速度。超疏水表面上液滴迁移的流体动力学表现出滚动行为，而对于光滑润滑剂浸渍表面，则观察到滚动和滑动的组合。超过临界气流速度后，所有表面上都会发生完全的液滴脱落。已经测量了超疏水和光滑表面上液滴的润湿长度和位置。在光滑表面上，液滴的速度受润滑剂性能的影响很大，而在润湿长度方面观察到类似的行为。
