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

Abstract

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.

Underwater Sound Propagation Modeling in a Complex Shallow Water Environment

“…The application of normal mode theory in underwater acoustics goes back to the 1940s (Pekeris, 1948). Since the early 1990s several 3D underwater propagation models based on the normal mode theory have been proposed (e.g., Porter, 1992;Luo and Schmidt, 2009;Ballard et al, 2015;DeCourcy and Duda, 2020). In normal mode models, the 2D horizontal refraction equation can be handled by several different techniques, including rays (e.g., Weinberg and Burridge, 1974), Gaussian beams (Porter, 1992), and also PEs (e.g., Petrov et al, 2020).…”

“…Unlike another software Field used for 2D environments, Field3D does not have the modecoupling option, and the sound pressure field in Kraken3D is calculated with an adiabatic (uncoupled) mode assumption. Although the adiabatic approach has many advantages, it is not expected to always provide accurate solutions for some frequencies and environments as shown by DeCourcy and Duda (2020). Kraken3D is often run in the azimuth independent (Nx2D) mode, but can consider horizontal refraction using the beam tracing method (Porter, 1992).…”

“…Examples include the assessment of underwater noise induced by offshore wind farms (Dahl and Dall'Osto, 2017;Lin et al, 2019) and the influence of estuarine salt wedges on sound propagation (Reeder and Lin, 2019). A number of 3D ocean acoustic propagation models have been developed over the past decades (e.g., Jones et al, 1986;Lee et al, 1992;Porter, 1992, Porter, 2016Bucker, 1994;Smith, 1999;Luo and Schmidt, 2009;Heaney and Campbell, 2016;Lin, 2019;DeCourcy and Duda, 2020). Still, simulating underwater sound propagation accurately for fully 3D environments involves significant scientific challenges and can demand high computational costs (e.g., Jensen et al, 2011;Lin et al, 2019).…”

“…Still, simulating underwater sound propagation accurately for fully 3D environments involves significant scientific challenges and can demand high computational costs (e.g., Jensen et al, 2011;Lin et al, 2019). According to their governing equations and numerical schemes, 3D underwater acoustic models can be divided into three main groups: parabolic equation (PE) models (e.g., Lin and Duda, 2012;Heaney and Campbell, 2016), normal mode models (e.g., Porter, 1992;DeCourcy and Duda, 2020), and ray and beam tracing models (e.g., Porter, 2016;Calazan and Rodríguez, 2018).…”

A 3D acoustic propagation model for shallow waters based on an indirect Boundary Element Method

“…A great variety of models have been developed to estimate underwater sound propagation in 3D scenarios that, according to their governing equations and numerical approaches, can be categorized into three main groups [4], namely, (a) extended parabolic equation (PE) models, such as the efficient marching solution based on the parabolic equation proposed by [12] that is applied to a local and to a global ocean environment by [6] and [5], respectively; (b) normal mode models [7,8,9]; and (c) ray and beam tracing models [10,11]. However, modelling acoustic propagation for 3D environments is still a significant two-fold challenge due to both the difficulties associated with a thorough comprehension of the physical phenomenon and the high computational time costs.…”