Predicting underwater sound radiation and directivity pattern of vibrating structures in deep and shallow water

Noise and vibration simulation using classical methods such as Finite Element Method (FEM), Boundary Element Method (BEM) and Statistical Energy Analysis (SEA) are well integrated into standard design processes in the automotive, aerospace and train industry. In the marine industry, simulation starts to occupy a key role in product design as vibro-acoustics and environmental requirements are becoming increasingly demanding. This paper discusses new advances in marine vibro-acoustic predictions and in particular the effect of water loading of hull panels and underwater sound radiation. A newly developed wavelet based sound radiation formulation is used to load hull panels with sea water which allows for the computation of the ship's water loaded natural frequencies and modal damping. This allows proper vibration level predictions on the hull panels for a wide range of frequencies. This paper also presents an innovative use of Fast Multipole Boundary Element Method (FMM-BEM) to predict underwater sound radiation of vibrating structures in deep or shallow waters. Several application examples using a 70 m luxury yacht model are also described.