Study of the cavity and hydrodynamic characteristics of water entry for projectiles with different wave parameters

Waves are a common phenomenon, and studying the influence of waves on water entry is more relevant in complex ocean environments. On the basis of the VOF model, Schnerr–Sauer cavitation model, and velocity boundary wave generation method, this paper numerically simulates the water entry process of projectiles considering various wave heights, wave directions, and positions, with a water entry angle of 60°. The effects of waves on the evolution of water entry cavities and hydrodynamic characteristics are analysed, and the accuracy of the numerical method is validated through experiments. These findings indicate that higher wave heights promote cavity expansion and increase the peak impact pressure during water entry. When the wave height is 1.3 m, the impact pressure peak increases by 30.9% compared with that in a hydrostatic environment. Additionally, the wave direction has little effect on cavity evolution but significantly affects hydrodynamic characteristics. Upstream water entry results in greater impact loads. Furthermore, water entry at the wave crest provides better stability but significantly increases the impact load. Water entry at the wave trough suppresses cavity expansion, resulting in faster cavity closure and the shallowest pinch-off position. This work provides a reference for enhancing the motion stability and structural safety of projectiles during water entry under complex ocean conditions.