Directional droplet bouncing on a moving superhydrophobic surface

作者：Meng Wang, Yan-Zhao Shi, Shun Wang, Huanlin Xu, Hui Zhang, Min Wei, Xiaopeng Wang, Wanxi Peng, Hang Ding, Meirong Song · 发表于：iScience · 年份：2023 · DOI：10.1016/j.isci.2023.106389 · 被引用次数：18 · 研究领域：Surface Modification and Superhydrophobicity、Fluid Dynamics and Heat Transfer、Fluid Dynamics Simulations and Interactions

Droplets directionally bouncing off moving superhydrophobic solid surfaces are universal in nature and are crucial in many biological, sustainable, environmental, and engineering applications. However, their underlying physics and regulation strategies remain relatively unknown. This paper demonstrates that the maximum directional acceleration of a post-impact droplet mainly occurs in the spreading stage and that the orientational velocity of the droplet mainly originates in the early impingement process. Furthermore, it clarifies the underlying physics based on momentum transfer process imposed by the boundary layer of impacts and proposes a strategy for regulating the directional droplet velocity using a comprehensive formula. Finally, it shows that directional bouncing reduces the flight momentum of a small flying device by 10%-22%, and the experimental values agree closely with the predicted values. This study reveals the droplet bounce orientation mechanism imposed by moving substrates, provides manipulation methods, and makes positive and meaningful discussions of practical applications.