A coupling procedure for modeling acoustic problems using finite elements and boundary elements

Abstract
Finite element (FEM) and boundary element (BEM) methods have been used for a long time for the numerical simulation of acoustic problems. The development presented in this paper deals with a general procedure for coupling acoustic finite elements with acoustic boundary elements in order to solve efficiently acoustic problems involving non homogeneous fluids. Emphasis is made on problems where finite elements are used for a confined (bounded) fluid while boundary elements are selected for an external (unbounded) fluid. The discrete sets of equations related to the two models are first summarized. An elimination procedure is then proposed for solving the coupled problem. This procedure enables to take care of the sparseness of the finite element matrix and leads to solve an updated boundary element system. The solution sequence allows for the treatment of multiple load cases (velocity boundary conditions) in order to generate mutual impedance coefficients.