H Biroun Mehdi, Rahmati Mohammad, Tao Ran, Torun Hamdi, Jangi Mehdi, Fu Yongqing
Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, U.K.
Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
Langmuir. 2020 Sep 1;36(34):10175-10186. doi: 10.1021/acs.langmuir.0c01628. Epub 2020 Aug 21.
Droplet impact on arbitrary inclined surfaces is of great interest for applications such as antifreezing, self-cleaning, and anti-infection. Research has been focused on texturing the surfaces to alter the contact time and rebouncing angle upon droplet impact. In this paper, using propagating surface acoustic waves (SAWs) along the inclined surfaces, we present a novel technique to modify and control key droplet impact parameters, such as impact regime, contact time, and rebouncing direction. A high-fidelity finite volume method was developed to explore the mechanisms of droplet impact on the inclined surfaces assisted by SAWs. Numerical results revealed that applying SAWs modifies the energy budget inside the liquid medium, leading to different impact behaviors. We then systematically investigated the effects of inclination angle, droplet impact velocity, SAW propagation direction, and applied SAW power on the impact dynamics and showed that by using SAWs, droplet impact on the nontextured hydrophobic and inclined surface is effectively changed from deposition to complete rebound. Moreover, the maximum contact time reduction up to ∼50% can be achieved, along with an alteration of droplet spreading and movement along the inclined surfaces. Finally, we showed that the rebouncing angle along the inclined surface could be adjusted within a wide range.
液滴撞击任意倾斜表面在诸如防冻、自清洁和抗感染等应用中具有重大意义。研究一直聚焦于对表面进行纹理化处理，以改变液滴撞击时的接触时间和反弹角度。在本文中，我们利用沿倾斜表面传播的表面声波（SAW），提出了一种新颖的技术来修改和控制关键的液滴撞击参数，如撞击模式、接触时间和反弹方向。开发了一种高保真有限体积法来探究在表面声波辅助下液滴撞击倾斜表面的机理。数值结果表明，施加表面声波会改变液体介质内部的能量收支，从而导致不同的撞击行为。然后，我们系统地研究了倾斜角度、液滴撞击速度、表面声波传播方向和施加的表面声波功率对撞击动力学的影响，并表明通过使用表面声波，液滴在无纹理的疏水倾斜表面上的撞击有效地从沉积转变为完全反弹。此外，最大接触时间可减少约50%，同时液滴沿倾斜表面的铺展和移动也会发生改变。最后，我们表明沿倾斜表面的反弹角度可以在很宽的范围内进行调整。
