ACOUSTIC POINT-SOURCE SCATTERING BY A SPHERICAL ELASTIC SHELL SUBMERGED BENEATH A FREE-SURFACE

The scattering of incident acoustic plane waves by a submerged spheric al elastic shell near a free surface has previously been analyzed in d etail using an exact, classical separation of variables solution. The problem is studied here again for cases where the incident waves are e mitted from point sources at arbitrary positions in space. The result demonstrates that for a nearby point source, the scattered wave field is signifcantly different from that due to a plane incident wave, and that when the distance from the point source to the shell is more than 20 shell radii, the backscattered echo can be closely approximated by that of a plane incident wave. The scattered field due to an array of point sources can also be obtained by linear superpositions of the so lution developed here.