Prediction of Acoustic Wave Propagation in the Vicinity of a Wedge Costal Region Using an Efficient Numerical Model

Abstract

Different boundary-only numerical frequency domain formulations are here developed and applied to simulate the two-dimensional (2D) acoustic wave propagation in the vicinity of a underwater configuration. This configuration combines two sub-regions, one of them being a wedge with rigid bottom and free surface, and the second one being a waveguide with a rigid flat bottom and a free flat surface. Both the Boundary Element Method (BEM) and the Method of Fundamental Solutions (MFS) are used to solve this problem. In either cases, Green’s functions that take into account the presence of flat rigid and free surfaces of the waveguide and of a wedge are used. A sub-region technique is used to connect the two parts of the domain, enforcing continuity of the relevant quantities. The Green’s functions are defined using two approaches: the image source method is used to model the rigid flat bottom and free flat interface, whereas the response provided by the wedge sub-region is based on a normal mode solution. A third boundary element formulation is also considered, which makes use of Green’s functions for a perfect waveguide (using the image source method), therefore requiring the discretization of the sloping rigid bottom of the wedge. The
presented formulations are discussed, both in what concerns accuracy and computational effort. The results obtained by the authors indicate that the MFS has a significantly lower computational cost and is very stable, therefore being adequate for the analysis of acoustic wave propagation in the studied configurations.