Observation of splash generated immediately after the impact of a high-speed droplet in a low-pressure

Abstract

When a droplet impacts on a solid surface, splash can be often observed. Wide varieties of physical parameters must be considered for the splash generation. In this study, we investigate the effects of the impact velocity and surrounding gas pressure on the generation of splash. We experimentally observed high-speed droplet impact on a cover glass in a reduced-pressure chamber using the high-speed video camera with the frame rate up to one million f.p.s. We discovered a different type of splash from those previously reported in the high-speed droplet impact under a low-pressure. The ejection of this splash can be found when the impact velocity is greater than a threshold velocity regardless of the surrounding gas pressure and surrounding gas species.