Analysis and Optimization of Absorbing Boundary Methods for Acoustic Wave Modelling

Abstract

This paper presents numerical simulations obtained via a 10-4 (10th order in space and 4nd order in time) staggered-grid finite difference scheme applied to acoustic waves. Our goal is to enhance the classical absorbing boundary methods – namely Absorbing Boundary Condition (ABC), Damping Zone (DZ) and Perfect Matched Layer (PML) – in order to minimize the spurious reflections associated with, improving the quality of the numerical results and reducing its computational effort. ABC, PML and DZ methods are implemented and tested for different coefficients and varying absorbing layers and are also combined. It has been found that both optimizations increase the effectiveness of the absorbing layer, with better absorption efficiencies for the ABC and optimized Cerjan and PML methods. Those methods can reduce significantly the artificial reflections at the boundaries when compared to the conventional attenuation coefficients. Results also show that side effects are very sensitive to the number of grid points used in the absorbing layer, with better results found for larger discretization points.