Perfectly matched layers for acoustic waves in viscous media: Applications to underwater acoustics

Berenger’s perfectly matched layer (PML) has recently been proved to exist for elastodynamic equations [Chew and Liu, Schlumberger‐Doll‐Res. Rep. (1995)]. This fictitious material absorbs all waves with an arbitrary incident angle and an arbitrary frequency without giving rise to any reflections. Therefore, when used as an absorbing boundary condition (ABC) at the computational edge in a finite‐difference method, the PML provides orders of magnitude higher absorption than other existing ABCs. In this work, the PML is further extended as an ABC for a finite‐difference simulation of acoustic waves in viscous media. For such attenuative media, an additional term involving the time‐integrated wavefield is introduced to account for the coupling between the attenuation from the PML and the normal viscous attenuation. This ABC is highly effective in absorbing outgoing waves at the computational edge even when a dipping interface intersects the outer boundary. This new material ABC is ideal for parallelization on...