A 3d-BEM for underwater propeller noise propagation in the ocean environment including hull scattering effects

Commercial ships and ocean vehicles could contribute significantly to underwater noise propagating in the marine environment, and propellers are considered to be a main source. International Organizations have issued guidelines for the reduction of shipping noise that has been identified as an important pollutant and is examined under Marine Strategy Framework (descriptor 11) in order to mitigate adverse impacts on marine life. In this work, we consider the propagation of noise generated by cavitating propellers arranged at the stern of ships and underwater vehicles including the hull scattering effects. The three-dimensional scattering problem is treated in the frequency domain by a Boundary Element Method (3 d-BEM), with excitation by monopole and dipole source terms of the Ffowcs Williams and Hawkings (FW-H) equation, taking into account the free-surface and bottom boundary effects. Numerical results are presented for selected cases illustrating that the hull geometry and the ocean acoustic properties, as well as the sea surface and seabed effects are important for the estimation of the acoustic field emitted from the above sources and the characteristic features of propeller noise propagation in the ocean environment.