Yun Sungchan
Department of Mechanical Engineering, Korea National University of Transportation, Chungju 27469, Republic of Korea.
Langmuir. 2020 Dec 8;36(48):14864-14871. doi: 10.1021/acs.langmuir.0c02898. Epub 2020 Nov 24.
Reducing the residence time of drops on solids has been attracting much attention in a wide range of industrial methods, such as self-cleaning and anti-icing. Classical drop dynamics is generally confined to circular symmetry and a theoretical limit of the bouncing time. In this study, we investigate the bouncing dynamics of ellipsoidal drops on cylindrical surfaces. Experimental and numerical results show that, compared with spherical ones, ellipsoidal shapes create the synergy effect of a preferential flow along the curved side, thereby leading to a significant reduction in the residence time when the drop's major axis coincides with the cylinder's axial direction. The effects of the drop ellipticity and surface curvature on the bouncing dynamics are investigated for several Weber numbers and discussed through momentum analyses. The proposed concave/convex decorated models demonstrate the feasibility of the further reduced residence time by enhancing the asymmetry in the mass and momentum distributions. This study can provide a new perspective to shape-dependent impact dynamics by emphasizing the importance of the geometric configuration between ellipsoidal drops and anisotropic surfaces in determining the extent to which the dynamics are asymmetric.
减少液滴在固体表面的停留时间在自清洁和防冰等广泛的工业方法中备受关注。经典的液滴动力学通常局限于圆对称性和弹跳时间的理论极限。在本研究中，我们研究了椭球形液滴在圆柱表面上的弹跳动力学。实验和数值结果表明，与球形液滴相比，椭球形会产生沿曲面优先流动的协同效应，从而当液滴的长轴与圆柱的轴向一致时，导致停留时间显著减少。针对几个韦伯数，研究了液滴椭圆率和表面曲率对弹跳动力学的影响，并通过动量分析进行了讨论。所提出的凹凸装饰模型证明了通过增强质量和动量分布的不对称性进一步减少停留时间的可行性。本研究通过强调椭球形液滴与各向异性表面之间的几何构型在确定动力学不对称程度方面的重要性，可为形状依赖的碰撞动力学提供新的视角。
