Three-dimensional acoustic propagation model for shallow waters based on an indirect boundary element method

This work has a two-fold purpose. On the one hand, the theoretical formulation of a three-dimensional (3D) acoustic propagation model for shallow waters with a constant sound speed is presented, based on the boundary element method (BEM), which uses a half-space Green function instead of the more conventional free-space Green function. On the other hand, a numerical implementation is illustrated to explore the formulation in simple idealized cases, controlled by a few parameters, which provides necessary tests for the accuracy and performance of the model. The half-space Green’s function, which has been previously used in scattering and diffraction, adds terms to the usual expressions of the integral operators without altering their continuity properties. Verifications against the wavenumber integration solution of the Pekeris waveguide suggest that the model allows an adequate prediction for the acoustic field. Likewise, numerical experiments in relation to the necessary mesh size for the description of the water-marine sediment interface lead to the conclusion that a transmission loss prediction with acceptable accuracy can be obtained with the use of a limited mesh around the desired evaluation region.