A coupled mode model for omnidirectional three-dimensional underwater sound propagation

Author Posting. © Acoustical Society of America, 2020. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 148(1), (2020): 51-62, doi:10.1121/10.0001517.A fully three-dimensional (3D) omnidirectional numerical coupled mode model of acoustic propagation is detailed. A combination of normal mode and finite element computational methods is applied to produce the numerical results. The technique is tested in a strongly range-dependent ocean environment modeled after the Hudson Canyon. Modeled sound from three source locations selected over different bathymetric depths is examined to determine capabilities and difficulties associated with varying numbers of propagating vertical modes across the horizontal domain, and variable amounts of mode coupling. Model results are compared to those from a unidirectional Cartesian 3D parabolic equation simulation, and from adiabatic (uncoupled) simulations to illustrate the capabilities of the techniques to study the influences of coupling, strong refraction, and reflection.This work was supported by the Office of Naval Research under a grant to Woods Hole Oceanographic Institution [Grant No. N00014-18-1-2172 which is a Postdoctoral Fellowship for B.J.DeC.]. T.F.D. acknowledges ONR Ocean Acoustics Program Grant No. N00014-17-1-2624.2021-01-0