Wave-induced hydroelastic vibration and underwater radiated noise of partially submerged marine panels

Wave-induced hydroelastic vibration of hull panels contributes to underwater noise from marine structures operating near the free surface. This study employs a coupled multiphase fluid–structure interaction framework with a modal structural representation and a Ffowcs Williams–Hawkings acoustic formulation to resolve the radiation mechanisms of partially submerged panels subjected to regular waves. Broadband sound pressure levels indicate that dipole radiation from hydrodynamic loading dominates the overall averaged response. Spectral decomposition reveals two dynamically distinct regimes. In the low-frequency band, radiation is loading-controlled, reflecting the harmonic structure of the incident wave field. At higher frequencies, the response becomes deformation-controlled, governed by hydroelastic modal behavior, where radiation associated with surface-normal structural motion reflects the intrinsic modal organization of the panel. Increasing immersion modifies the coupled eigenstructure through added-mass effects, compressing modal spacing and redistributing modal energy from a unimodal state toward multimodal participation, transforming the acoustic signature from narrowband tonal radiation to broadband behavior. When evaluated using sound exposure level, this modal redistribution produces systematic shifts in the spectral energy distribution across frequency bands. The results show that immersion changes hydroelastic modal participation and, through free-surface interference, modifies the underwater acoustic spectrum, guiding structural noise control in near-surface marine panels.