Scattering by spheres buried in sediment

Abstract

In this report the scattering of acoustic energy by an elastic sphere buried in sediment is examined. The geoacoustic model consists of two homogeneous fluid halfspaces separated by an intermediate layer. The source field is generated by either a point source or a vertical line array placed in the upper halfspace. The spherical shell is placed in the lower fluid halfspace

and the scattered field is computed at an observation point placed at various locations in the upper halfspace. The scattered field is computed with a modified T-matrix based approach. We examine how the physical parameters of the sediment (attenuation, density and velocity) and geometrical parameters such as the burial depth and the insonification angle, affect the backscattered field amplitude. The numerical results presented in this report are for an evacuated, steel shell that has a thickness of 3% of the outer radius.