An axisymmetric time-domain spectral-element method for full-wave simulations: Application to ocean acoustics

TL;DR

This paper introduces an axisymmetric time-domain spectral-element method for simulating acoustic waves in complex 3D media, enabling efficient and accurate modeling of ocean acoustics phenomena with reduced computational costs.

Contribution

It presents a novel axisymmetric spectral-element approach for full-wave simulations in heterogeneous media, validated and applied to ocean acoustics scenarios.

Findings

Method accurately models backscattered waves.

Enables study of 3D configurations at moderate computational cost.

Explains transmission loss discrepancies in ocean acoustics.

Abstract

The numerical simulation of acoustic waves in complex 3D media is a key topic in many branches of science, from exploration geophysics to non-destructive testing and medical imaging. With the drastic increase in computing capabilities this field has dramatically grown in the last twenty years. However many 3D computations, especially at high frequency and/or long range, are still far beyond current reach and force researchers to resort to approximations, for example by working in 2D (plane strain) or by using a paraxial approximation. This article presents and validates a numerical technique based on an axisymmetric formulation of a spectral finite-element method in the time domain for heterogeneous fluid-solid media. Taking advantage of axisymmetry enables the study of relevant 3D configurations at a very moderate computational cost. The axisymmetric spectral-element formulation is first introduced, and validation tests are then performed. A typical application of interest in ocean acoustics showing upslope propagation above a dipping viscoelastic ocean bottom is then presented. The method correctly models backscattered waves and explains the transmission losses discrepancies pointed out in Jensen et al. (2007). Finally, a realistic application to a double seamount problem is considered.