The perfectly matched layer for elastic waves in poroelastic media

Abstract

The perfectly matched layer (PML) as a material absorbing boundary condition (ABC) was first introduced by Berenger for electromagnetic waves, and later developed by Chew and Liu for elastic waves. In the continuous limit, an interface between a regular medium and a fictitious, lossy PML medium can be made perfectly matched so that there is no reflection from the PML to the regular medium. This property is independent of the incidence angle and the frequency of the incoming waves. Consequently, the PML provides an ideal ABC for the truncation of the computational domain in numerical methods such as the finite-difference, finite-element, and pseudospectral time-domain methods. Numerical experiments show that this ABC can reduce the reflection to several orders of magnitude below the level of the previous ABCs. In this work, the PML is further extended to elastic waves in poroelastic media through the approach of complex coordinates for Biot’s equations. This nonphysical material is used as an ABC at the computational edge of a finite-difference algorithm to truncate unbounded media. Numerical results show that the PML ABC attenuates the outgoing waves effectively.