A numerical study on water entry of cylindrical projectiles

Abstract

A series of numerical experiments carried out on the water entry of circular cylinders are presented in this study. A cylinder was entering into the water with a prescribed inclined angle and velocity. The interface between water and air is tracked by the piecewise linear interface calculation schemes in conjunction with the volume of fluid method. Overset meshes, which have been widely used for problems with relative motions, are applied to handle the moving cylinder. The numerical model is built on the framework of OpenFOAM, which is an open-source C++ toolbox. The results of the numerical model, such as the transient positions and inclined angles of the moving circular cylinder, have been validated with experimental data in the literature. The fluid physics of the oblique water entry problem has been examined. The formation and development of the air entrapment have been explored. Parametric studies on the hydrodynamics of the water entry problem have been performed. It has been revealed that the head geometry, entry impact velocity, entry inclined angle, liquid density, and object density are of considerable significance for the penetration depth and inclination of the diving cylinder. Surface wetness, which affects the detachment of the air channel, has also been studied.