Investigation of cavity and jet evolution mechanisms during porous plate water entry under different velocities

Water entry is a complex process in marine engineering, marked by highly dynamic and intricate flow behavior. This study investigates the dynamic characteristics of cavity evolution during the water entry of a porous plate through experimental and numerical methods. A numerical model based on the smoothed particle hydrodynamics (SPH) method was developed and validated against experimental data under various velocities. The results indicate that the model accurately captures key stages of cavity evolution, showing good agreement with experiments across different velocity values. Detailed analysis of cavity and jet evolution reveals distinct mechanisms of jets driven by pressure distribution, along with corresponding energy dissipation patterns. Parametric studies indicate that cavity width, pinch-off time, and jet height all exhibit a linear positive correlation with water-entry velocity, with jet height being more sensitive to variations in velocity. The cavity and jet of the porous plate are smaller than those of the flat plate under the same conditions. Furthermore, post-pinch-off flow field evolution exhibits four typical dynamic zones, where interactions between upward and downward flows induce significant velocity fluctuations of the porous plate. These findings provide theoretical insights into the hydrodynamic behavior of porous structures during water entry and offer valuable guidance for modeling and optimizing impact problems in marine engineering applications.