Hybrid normal mode and energy flux model for an ideal oceanic wedge environment with radial sound speed front

TL;DR

This paper develops a three-dimensional hybrid acoustic propagation model combining normal modes and energy flux methods for an oceanic wedge with a radial sound speed front, enabling better analysis of complex underwater sound environments.

Contribution

It introduces the first 3D hybrid model using normal modes and energy flux for wedge environments with radial sound speed fronts, expanding the applicability of energy flux methods.

Findings

The hybrid model shows general agreement with normal mode models in caustic features.

Discrepancies observed may be due to differences in model derivations.

This work advances toward a more general 3D energy flux model.

Abstract

Energy flux is an acoustic propagation model that calculates the locally-averaged intensity without computing explicit eigenvalues or tracing rays. The energy flux method has so far only been used for two-dimensional problems that have collapsed the third dimension by rotational or translational symmetry. This report outlines the derivation and implementation of a three-dimensional ocean acoustic propagation model using a combination of normal modes and the energy flux method. This model is specifically derived for a wedge environment with a radial sound speed front at some distance from the shoreline. The hybrid energy flux model's output is compared to that of another propagation model for this environment that is built on normal modes alone. General agreement in the shape, location, and amplitude of caustic features is observed with some discrepancies that may be attributable to inherent differences in the model derivations. This work serves as a stepping-stone toward developing a more generalized three-dimensional energy flux model.