Cavity dynamics following the vertical entry of different-density spheres into a stratified system of viscous liquid floating on water

Abstract

This paper explores the physical phenomena of different-density spheres passing vertically through a stratified liquid containing high-viscosity dimethicone on the water surface. High-speed photography to monitor the cavity evolution and a hydrophone used to record the acoustic features. The results show that the thickness of the dimethicone layer and the density of the sphere have a significant impact on the shape of the splash crown, especially regarding the form of surface sealing and the time at which it occurs. As the thickness of the dimethicone layer increases and the density of the sphere decreases, the shrinkage time of the splash crown of the water layer is delayed, and the number of surface sealing events tends to decrease. Furthermore, the thickness of the dimethicone layer has a significant effect on the deep pinch-off phenomenon for high-density spheres and exhibits a weaker influence on low-density spheres. Moreover, examination of the acoustic signals indicates that the cavity evolution is closely related to acoustic properties, and the thickness of the dimethicone layer presents different effects at different stages of the entering process. These results indicate that the dimethicone layer and the density of the spheres have a considerable influence on cavity development and acoustic features in the wake of water entry.