Scattering of acoustic waves by a scatterer in a layered medium.

Abstract

In this paper, the scattering of acoustic waves by a scatterer in a layered medium is considered. The crucial steps of the analyses are the application of direct boundary element formulation together with a suitable Green’s function solution. The needed Green’s function is constructed by a global matrix technique. The essence of the method is the use of pressure at each interface (including the outer surface) as basic unknowns. The continuity of pressure along the interfaces of the multilayered medium is then ensured automatically. These as yet undetermined interface pressures are finally determined from the boundary conditions at the outer surface of multilayered medium and the continuities of normal velocities along interfaces. The resulting linear system of equations is straightforward assembled and manifested in a global form. The sizes of the matrices are only N×N, which is only 1/4 of storage of the original global matrix formulation proposed by Schmidt. The complete scattering is then computed by boundary element and compared against the results obtained by PE. In the cases of acoustic scatterer, PE is presumed to work quite well, at least in the forward propagation portion. The effects of elastic scatterer are then discussed.