In this work, a method named Nearly Perfectly Matched Layer (NPML) using a Complex Frequency Shift (CFS) stretched-coordinate metrics is presented to extend the Perfectly Matched Layer (PML) to simulate elastic wave propagation in solid media. This non-physical layer is used at the computational edge of a Discontinuous Galerkin Finite Element Method (DG-FEM) algorithm and a Pseudo-Spectral (PS) algorithm in time domain, as an Absorbing Boundary Condition (ABC) to truncate unbounded media. The main advantages of NPML is linked to the facts that (a) the obtained system of equations has the same form exactly as the original system of equations and so strongly hyperbolic, and (b) the introduced NPML variables are updated by Ordinary Differential Equations (ODE) in place of Partial Differential Equations (PDE) in classical PML implementation. Numerical results show that the NPML has the same ability of energy absorption as the Convolutional Perfectly Matched Layer (CPML) for attenuating the outgoing waves, moreover, it facilitates implementation in the DG-FEM scheme than CPML and preserves the highly parallelisable capabilities of this numerical scheme.
The Journal of the Acoustical Society of America 04/2012; 131(4):3443. DOI:10.1121/1.4708932 · 1.65 Impact Factor