Numerical investigation of sequential water entry for two projectiles at varied entry angles

Abstract

In this paper, the effect of the water entry angle on the sequential water entry process of two projectiles was investigated numerically. A numerical method is established based on the STAR-CCM+ fluid simulation software, which employs the finite volume method, the volume of fluid multiphase flow model, and overlapping grid technology. The validity of the numerical method was confirmed by comparing the simulation results with experimental data. The sequential water entry processes are simulated at angles of 90°, 75°, 60°, 45°, and 30°, respectively. The flow field characteristics, motion stability, and drag reduction of both projectiles are analyzed. The results show that projectile 1 generates a series of air bubbles shedding from its cavity's tail, which distorts projectile 2's cavity. This air bubble reduces the wet area at projectile 2's head, enhancing its drag reduction capability. Projectile 1's motion remains unaffected by projectile 2 under varying water entry angles, while distinct motion characteristics are observed in projectile 2 due to significant interference from projectile 1. These results provide valuable theoretical insights for further research on sequentially launched trans-media weapons.