ASA 124th Meeting New Orleans 1992 October

5pPA8. Scattering by an obstacle embedded in a plane-stratified, saturated, poro-elastic medium: Application to an obstacle in ocean sediments.

Raymond Lim

Code N1120, Coastal Systems Station, Panama City, FL 32407-5000

A transition matrix formalism for calculating the field scattered by a bounded, three-dimensional obstacle buried in a plane-stratified, saturated, poro-elastic environment is described. The formalism yields an exact solution of the vector Biot equations, obeying all boundary conditions prescribed on the layer and obstacle boundaries. This is obtained by combining the recently derived free-field transition matrix for an obstacle in a porous medium [Kargl and Lim, J. Acoust. Soc. Am. 90, 2371 (A) (1991)] with a generalization of existing acoustic waveguide formalisms [see, for example, Hackman and Sammelmann, J. Acoust. Soc. Am. 84, 1813--1825 (1988)]. The solution is numerically implemented for a spherical obstacle buried in a layered ocean sediment and insonified by an acoustic source in an overlying water half-space.