Research progress of droplet impact on dry curve surfaces

Abstract

The impact of liquid droplet on solid surfaces or liquid films occurs frequently in nature and industrial fields. Scholars have carried out many experimental and numerical simulation researches on the droplet impact phenomena, especially on the dynamic processes of the impact on the flat. The droplet impact on curve surfaces has special characteristics due to the shape differences between flats and curve surfaces. The research progress of the droplet impact on curve surfaces is summarized and the influence of the droplet impact velocity, surface wettability, curvature ratio, and impact angle on the dynamic characteristics is analyzed in this paper. The conclusions indicate that droplet impact process commonly includes the spread, retract, rebound and breakup or splash. If the droplet diameter is greater than the diameter of the curve surface, the spread process would turn into a coating process due to gravity. The rebound happens easily when a droplet impacts hydrophobic or superhydrophobic surfaces. The Splash happens more easily when the droplet has small surface tension or the surface has large roughness. Unsymmetrical spread occurs when a droplet obliquely impacts a curve surface, and the droplet would slide from one side or divide into two different parts. The study of the droplet impact on special curve surfaces, such as groove and dentate structures, is also summarized. The results indicate that the droplet tend to rebound on these special curve surfaces. Critical Weber number or critical dimensionless parameter K (K=Ren·Wem) is commonly used to describe the appearance of splashes.