Stable Variational Coupling Method for Fluid-Structure Interaction in Semi-Infinite Media

Abstract

An energy-based symmetric coupled finite element and boundary integral method valid for all frequencies has been developed recently by the authors (Zeng et al., 1990; Bielak et al., 1991), for analyzing scattering problems for an inhomogeneous deformable body immersed in an infinite acoustic medium. Here we extend the methodology to a halfspace with a free surface via the method of images. Numerical examples are presented for an infinitely long radially inhomogeneous elastic cylinder with its centroidal axis parallel to the free surface and subjected to an incident plane wave perpendicular to this axis, in order to illustrate the applicability of the new procedure; its accuracy at critical frequencies is assessed with a rigid cylinder.