Finite-element modeling of long range, range-dependent acoustic propagation in shallow water

Abstract

The current methods of modeling long range, low frequency acoustic propagation in shallow water environments include ray methods, wave number integration, parabolic equations, and normal mode theory. Finite-element (FE) models have also been considered in the past, but computing power and algorithm cost have limited their application. Recent advances in computing power coupled with the advent of low cost, user-friendly, all-purpose finite-element codes have provided new opportunities for the application of FE modeling. We present both time and frequency domain solutions to canonical acoustic problems (scattering from a corrugated surface and propagation in a Pekeris waveguide), and to two-way, range-dependent problems, such as waveguides with surface and bottom roughness. For the latter environment, reverberation time series produced by Fourier synthesis of the FE model output can potentially provide benchmark solutions that no other currently available solution method can provide. [Work supported by ARL IR&D.]