A perfectly matched layer for fluid-solid problems: Application to ocean-acoustics simulations with solid ocean...

Area of Science:

• Computational physics
• Ocean acoustics
• Numerical methods

Background:

• Ocean acoustics simulations require accurate modeling of coupled fluid-solid interactions.
• Handling unbounded domains and shear wave propagation in the seabed presents significant challenges.
• Existing methods often struggle with complex geometries and efficient wave absorption.

Purpose of the Study:

• To develop a time-domain spectral-element method for full-wave simulation of ocean acoustics.
• To introduce a novel fluid-solid complex-frequency-shifted unsplit perfectly matched layer (PML) for efficient wave absorption.
• To rigorously incorporate complex coordinate stretching into the PML formulation for improved accuracy.

Main Methods:

• A time-domain Legendre spectral-element method is employed.
• A fluid-solid complex-frequency-shifted unsplit PML is introduced, based on complex coordinate stretching.
• Two implementations are presented: convolutional and auxiliary differential equation (ADE) formulations.
• The ADE formulation facilitates high-order time-stepping schemes to minimize numerical dispersion and dissipation.

Main Results:

• The method accurately simulates coupled fluid-solid problems in unbounded domains.
• It effectively handles range- and depth-dependent properties and steep topography.
• The novel PML demonstrates superior absorption of body and interface waves compared to paraxial methods.
• Numerical simulations show long-time stability for 2D and 3D models.

Conclusions:

• The developed time-domain spectral-element method provides an accurate and stable approach for ocean acoustics.
• The novel fluid-solid PML offers significant advantages in wave absorption efficiency.
• This technique is particularly beneficial for long-range ocean acoustics simulations with complex features.