Beam tracing for two- and three-dimensional problems in ocean acoustics

Abstract

Beam tracing is an extension of ray tracing that constructs beams around the central rays radiating from a source. Typically, a fan of such beams is used to represent a point source and the field at any given location is computed by coherently summing all contributing beams. On a slightly superficial level, one points to the following key benefits: (1) improved accuracy because the beams smooth out singularities of the ray-theoretic field, and (2) algorithmic advantages because eigenrays precisely connecting the source and the receiver do not need to be identified. One may argue about these considerations; however, beam tracing methods have emerged as a very important class of methods for computing ocean acoustic fields. Interestingly, the published literature has not kept up with the numerous advances in beam tracing, including algorithmic developments that are important to efficient and robust implementations. Furthermore, there are quite a few variants of beam tracing algorithms with very different characteristics. This article discusses these variants, significant advances in practical implementation, and performance characteristics.

Channel Modeling for Underwater Acoustic Network Simulation

“…see [26]- [32]. BELLHOP is a beam/ray tracing model for predicting acoustic pressure fields in the underwater environment [17] [18], which is publicly available as part of the Acoustics Toolbox [33], originally developed by M. Porter and currently maintained by the Woods Hole Oceanographic Institute. Beam/ray tracing is based on ray theory which approximates the propagation of acoustic waves as rays travelling along particular spatial paths from the source to the receiver [34].…”

“…based on ray/beam tracing or normal mode calculations [15]. A popular open source platform for this is BELLHOP [17] [18], which employs beam tracing to predict acoustic pressure fields in specified underwater environments. There are multiple extensions to BELL-HOP that enable the researchers to adopt it in their studies, e.g.…”

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

“…The relative difference is computed as diff ¼ 2ð log 10 jR n j À log 10 jR ð0Þ n jÞ= ð log 10 jR n j þ log 10 jR ð0Þ n jÞ, similar to the relative difference calculation in Eq. (9). At points where both À20 log 10 jR n j > 120 and À20 log 10 jR ð0Þ n j > 120, the relative difference calculation is forced to be zero, with the intention of deemphasizing the difference at locations where both the adiabatic and coupled mode amplitudes exhibit high energy loss.…”

“…[5][6][7] To avoid the difficulties inherent in handling mode coupling and to make higher source frequency computations easier, ray theory 8 and beam-tracing have been used. 9 The ray and beam methodologies inherently include omnidirectional wave propagation in three dimensions which is a strength of these methods, but their applicability is limited in cases of low frequency or instances with surface ducts. 9 Another popular acoustic calculation approach is the Parabolic Equation (PE) method.…”

“…9 The ray and beam methodologies inherently include omnidirectional wave propagation in three dimensions which is a strength of these methods, but their applicability is limited in cases of low frequency or instances with surface ducts. 9 Another popular acoustic calculation approach is the Parabolic Equation (PE) method. 10,11 The fundamental PE approach increases numerical efficiency by including only the forwardpropagating portion of the acoustic field, clearly excluding many propagation and scattering effects.…”