关键词: 复频移PML, 吸收边界条件, 弹性波, 数值模拟, 递推卷积方法

Abstract:

The perfectly matched layer (PML) absorbing boundary condition has proven to be a very efficient method for the numerical forward modeling of elastic wave equation to absorb both body waves and surface waves. But in some cases such as grazing incidence and the free surface in narrow domain the classical discrete PML method suffers from some serious problems. The complex frequency-shifted PML which uses the complex frequency-shifted stretch function in the coordinate transformation can efficiently improve the PML absorbing performance. We derived a recursive convolution method for implementing complex frequency-shifted PML and carried out the numerical simulation employing the staggered-grid higher-order finite-difference method based on the first-order partial differential wave equation. The results show that the complex frequency-shifted PML based on recursive convolution method can largely improve the absorbing effects in difficult cases. And its implementation is convenient because of the un-split variable. The cost of the calculation is not increase because of the recursion when convolution is computed. The memory storage is also similar to that of the classical PML.

Key words: complex frequency-shifted PML, absorbing boundary condition, elastic wave, numerical forward modeling, recursive convolution method