Numerical study of underwater acoustic radiation and propagation induced by structural vibration in ocean environments using FEM-BMSBM

Understanding underwater acoustic radiation and propagation induced by structural vibration in the ocean environment involves analyzing the interaction between the ocean acoustic field and the structure. For this reason, this paper proposes a novel hybrid scheme integrating the finite element method (FEM), singular boundary method (SBM) and Burton-Miller (BM) technique. The three-dimensional and axisymmetric calculation formulations of the hybrid scheme are presented. By leveraging the respective strengths, the FEM simulates structural free vibrations, the SBM analyzes underwater acoustics in various ocean environments, and the BM technique resolves irregular frequency issues. The accuracy and feasibility of the hybrid FEM-BMSBM are confirmed by comparisons with experimental and other numerical results. The numerical findings demonstrate that the hybrid FEM-BMSBM alleviates the high computational cost of the traditional FEM and the ill-posed problem of the wave superposition method (WSM), and successfully mitigates irregular frequency phenomena of underwater acoustic simulations in various ocean environments. Additionally, the influence of the ocean surface and sediment on the underwater sound field is studied. Numerical study shows that the reflection effects of the ocean surface and sediment cause fluctuations in the underwater sound pressure level curve, and the number of side lobes of the sound pressure level curve increases with the increase of the excitation frequency.