Investigation of nano-droplet wetting states on array micro-structured surfaces with different gravity

B Xu and CC Zhang and ZQ Chen and Y Yang and Q Cao, COMPUTERS & FLUIDS, 222, 104936 (2021).

DOI: 10.1016/j.compfluid.2021.104936

In order to obtain the influence law and microscale mechanism of droplet wetting state in microgravity, the model of nano-droplet on array micro- structured surface with different wettability and gravity was built and simulated by molecular dynamics. In conditions of no gravity, it was found that critical point of wetting state transition was closer to weak wettability surface with the decrease of low range micro-column height. What's more, the droplet contact angle increased first and then decreased with larger micro-column height when h* < 1.5. Under the action of gravity, the droplet Cassie state basically did not appear. The greater gravity made the droplet wetting state transition (from Cassie to Wenzel-Cassie to Wenzel) need lower requirements for surface wettability and micro-column height. Moreover, micro-gravity environment was conducive to droplets transition from Wenzel to Wenzel-Cassie or Cassie state, which promoting droplet drainage. Finally, a simple, effective and reliable method was put forward to judge the droplets wetting state under different gravity, with the aim of providing a technical support for controlling droplet to be in Wenzel-Cassie state under gravity. (C) 2021 Elsevier Ltd. All rights reserved.

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