Optimal damping ratios of multi-axial perfectly matched layers for elastic-wave modeling in general anisotropic media

TL;DR

This paper introduces a quantitative method to determine optimal damping ratios for multi-axial PMLs, enhancing stability and reducing artificial reflections in elastic-wave simulations in complex anisotropic media.

Contribution

A novel quantitative approach for calculating damping ratios in MPMLs that improves stability and minimizes reflections in elastic-wave modeling of anisotropic media.

Findings

Effective stabilization of PMLs in anisotropic media

Reduction of artificial reflections in simulations

Applicable to 2D and 3D elastic-wave models

Abstract

The conventional Perfectly Matched Layer (PML) is unstable for certain kinds of anisotropic media. This instability is intrinsic and independent of PML formulation or implementation. The Multi-axial PML (MPML) removes such instability using a nonzero damping coefficient in the direction parallel with the interface between a PML and the investigated domain. The damping ratio of MPML is the ratio between the damping coefficients along the directions parallel with and perpendicular to the interface between a PML and the investigated domain. No quantitative approach is available for obtaining these damping ratios for general anisotropic media. We develop a quantitative approach to determining optimal damping ratios to not only stabilize PMLs, but also minimize the artificial reflections from MPMLs. Numerical tests based on finite-difference method show that our new method can effectively provide a set of optimal MPML damping ratios for elastic-wave propagation in 2D and 3D general anisotropic media.