Effects of wave diffraction around rigid walls with typical geometries on cavitation loads induced by underwater explosions

Abstract

Wave diffraction around rigid walls of varying geometries critically affects cavitation and collapse-induced loading during underwater explosions. This study develops a numerical framework integrating Runge–Kutta discontinuous Galerkin discretization, Level Set interface tracking, the ghost fluid method, and an isentropic cavitation model. Validation against representative one- and two-dimensional benchmarks confirms the framework's accuracy and robustness in capturing shock propagation, interface evolution, and cavitation inception, growth, and collapse. The validated model is used to examine the effects of wall thickness, length, and configuration, stand-off distance, and charge depth on cavitation evolution and wall loading. The results show that interactions among incident, reflected, and edge-diffracted waves govern the cyclic inception, expansion, collapse, and regeneration of near-wall cavitation. Increasing wall thickness enhances near-wall confinement, producing more concentrated cavities and higher initial collapse loads, whereas increasing wall length prolongs the low-pressure state, enlarges the cavitation region, and intensifies collapse loading at the wall center. Increasing stand-off distance weakens and delays cavitation, while increasing charge depth suppresses cavity growth and accelerates collapse through elevated hydrostatic pressure. Wall configuration also strongly influences cavitation morphology and loading. The upright conical wall delays collapse but produces a central collapse load comparable to that of the cylindrical wall, whereas the inverted conical wall promotes oblique shock reflection and radial energy dispersion, substantially reducing cavitation severity and concentrated wall loading. These findings elucidate the mechanisms governing near-wall cavitation loads and provide a theoretical basis for the blast-resistant design of typical underwater structures.