A Traveltime-based Absorbing Boundary Condition and Fourth-order Implicit Procedures for the Simulation of Acoustics

For the simulation of waves in a bounded domain, the absorbing boundary condition (ABC) must be set appropriately to suppress the wave reflection on the boundary. This article introduces a new traveltime-based ABC which can significantly reduce the boundary reflection. Also the article considers a new fourth-order implicit time-stepping scheme, which incorporates a locally one-dimensional procedure for an efficient simulation. Its stability and accuracy are analyzed and compared with those of the standard explicit fourth-order scheme. It has been observed from various experiments that the new ABC can reduce the boundary reflection by one order, compared with the conventional first-order ABC, and the implicit procedure produces less dispersive solutions than the explicit scheme in heterogeneous media. Key-Words: Acoustic wave, absorbing boundary condition (ABC), high-order method, locally one-dimensional (LOD) method, numerical dispersion.