Comparisons between the hybrid ABC and the PML method for 2D high‐order finite‐difference acoustic modeling

Abstract

Absorbing boundary conditions (ABCs) are usually employed to absorb artificial reflections from model boundaries in numerical solution of wave equations. We compare a hybrid ABC that combines one way wave equation and damping, with the perfectly matched layer (PML) for 2D high‐order finite‐difference (FD) acoustic modeling. The 2nd‐order one‐way wave equations (OWWEs) based hybrid ABC provides better absorption effects than the 1st‐order OWWEs based one. Nearly perfect absorptions can be obtained by using the same‐order FD in the PML, overlap and inner areas. Both the 2nd‐order OWWEs based hybrid ABC and the PML ABC with high‐order FD in the PML area significantly absorb boundary reflections. They obtain nearly the same absorption effects for waves of approximately normal incidence. The PML ABC has better absorptions than the hybrid ABC for waves far from normal incidence but is more complicated and more expensive computationally. One possible way to improve absorption effects of the hybrid ABC further is to use high‐order OWWEs or high‐accuracy prediction formulations.