Acoustic radiation and scattering from shells of revolution using finite element and boundary element methods.

Abstract

The use of modal methods to determine acoustic transient and harmonic radiation and scattering from fluid loaded shells of revolution will be reviewed. Using such methods the velocity field of a fluid loaded shell is first expressed as an invacuo modal vector expansion where the modes are determined either analytically for simple structures or via finite element methods for more complex structures. Boundary element or other methods are subsequently used to evaluate mode-dependent acoustic radiation impedances and impulse responses which account for the coupling of the fluid. In contrast to the harmonic problem which results in sets of algebraic equations for the coefficients of the modal expansion, the transient problem results in sets of coupled time-dependent convolution integral equations for the time-dependent coefficients. Our experience in solving both two- and three-dimensional radiation and scattering problems using modal methods will be reviewed. Numerical results for a wide variety of two- and three-dimensional radiation and scattering problems will be presented. In particular results will be presented and discussed for cylindrical, spherical, and spheroidal shells.