A subtractive modelling approach for predicting the radiation of a cylindrical shell in a waveguide

Abstract

Numerical methods for predicting the underwater radiated noise of submerged structures are of paramount importance for ensuring high performance of systems for naval applications. When it comes to studying submerged structures in a shallow water environment, the influence of the sea surface and seabed cannot be neglected as strong coupling arises between the system and the environment boundaries. In this paper, the radiation from a cylindrical shell submerged in a perfect acoustic waveguide composed of an upper free surface and a rigid floor is investigated using a subtractive modelling approach based on the previously developed CTF (Condensed Transfer Function) and rCTF (reverse Condensed Transfer Function) methods. These methods enable prediction of the behavior of a system from the combination of the condensed transfer functions of the coupled and de-coupled subsystems which the original system is composed of. Following this principle, the radiation of the cylindrical shell in the waveguide can be investigated from the calculation of the condensed transfer functions of the waveguide, of the water volume occupied by the cylindrical shell, and of the uncoupled shell. Results from this approach are compared to a recently developed analytical procedure.