Analysis of Transient Acoustic-Elastic Interaction in an Unbounded Structure

Abstract

Consider the wave propagation in a two-layered medium consisting of a homogeneous compressible air or fluid on top of a homogeneous isotropic elastic solid in three dimensions. The interface between the two layers is assumed to be an unbounded rough surface. This work presents the first mathematical analysis for the transient acoustic-elastic interaction problem in such an unbounded structure. Using an exact transparent boundary condition and suitable interface conditions, we study an initial boundary value problem for the coupling of the acoustic and elastic wave equations. The well-posedness and stability are established for the reduced problem. Moreover, a priori estimates with explicit dependence on the time are obtained for the acoustic pressure and the elastic displacement. The problem addressed is sufficiently general to have potential use in applications.