A new artificial boundary condition for numerical simulation of elastic waves

Abstract

Disposition of artificial boundary condition (ABC) is important in numerical analysis of elastic waves propagating in infinite medium. A variety of ABCs have been proposed targeting different applications. However, the relatively high complexity or unsatisfactory accuracy of some of the methods make it difficult to broadly apply those boundaries. In this paper, a new ABC called material damping layer boundary (MDLB) is proposed, which not only ensures high accuracy and is easy to implement but also has a wider range of applications. Firstly, based on the u-U formulation of Biot's theory and the Kelvin damping model, the MDLB suitable for saturated porous media is constructed by introducing monotonically increasing material damping into the constitutive equations. Secondly, the MDLBs suitable for both 1D and 2D problems in single-phased media are degenerated directly from that for saturated media by neglecting the porosity. The attenuation functions of MDLB are recommended and the effects of the parameters of the attenuation functions on the performance of MDLB are investigated. It is found that the proposed MDLB could produce tremendous absorbing ability. In addition, the region for choosing the parameters of the attenuation functions is quite large, which makes the use of MDLB very convenient in many practical numerical simulations. Finally, comparisons with other ABCs are conducted and the better performance of the proposed MDLB are demonstrated.