Numerical Simulation of Cavity Dynamics and Motion Characteristics for Water Entry of a Hydrophobic Sphere at Various Speeds and Angles

Abstract

Water entry is a complex transient process involving free interface, and the physical mechanism of the cavity dynamics and kinematic characteristics under various initial motion states still are not clear. In this study, the unsteady characteristics of water entry of a hydrophobic sphere were investigated numerically and experimentally, focusing on the effects of various entry speeds and angles. A three-dimensional numerical method with six degrees of freedom was developed for the sphere water-entry process using the shear stress transport (SST) turbulence model based on volume of fluid (VOF) and overlapping grid technology, in conjunction with the corresponding experiments to provide the validation data. The results show that the variation in the entry speeds and angles affects not only the closure mode of the cavity but also the shape evolution and typical moments of the cavitation shape and jet, as well as the changes in force and motion characteristics.