An element for the analysis of transient exterior fluid-structure interaction problems using the FEM

Abstract

A finite element-based procedure is presented for the solution directly in the time domain of transient problems involving structures submerged in an infinite acoustic fluid. A central component of the methodology employed herein, and presented in greater detail elsewhere, is a novel element that arises upon discretization of a high-order absorbing boundary condition introduced in the formulation of the fluid-structure interaction problem in order to render the computational domain finite. The new element is local in both time and space and is completely defined by a pair of symmetric stiffness and damping matrices. The familiar form of the discritized equations of motion for the structure is retained with its symmetry and sparseness intact. Standard temporal integration techniques can then be used for the solution of the equations. In this paper we present the methodology in a two-dimensional setting, together with numerical examples involving both circular and non-circular shells. Although the focus is on the time domain, the methodology is equally applicable in the frequency domain, thus providing a unified and efficient tool for the treatment of the exterior structural acoustics problem.