各向异性介质中二阶弹性波方程模拟PML吸收边界条件

SIMULATION OF PML ABSORBING BOUNDARY CONDITION WITH SECOND-ORDER ELASTIC WAVE EQUATION IN ANISOTROPIC MEDIA

提出了基于弹性波动方程的二阶双曲系统的一种新的弹性波动方程模拟的最佳匹配层(PML)吸收边界条件。对于二阶系统方程,PML吸收边界条件模型通常是以四分裂位移参量来构建的,这种方法需要求解时间的三阶导数,且占用较多的计算空间;作为另一种选择,非分裂的PML算法可以扩展到二阶系统中,但它需要求解二重时间积分。新方法可克服或简化上述问题。用交错网格有限差分方法加最佳匹配层边界条件新算法的模拟方法用数值模型作了试验,结果证实了此方法的有效性。

A new alternative perfectly matched layer （PML） absorbing boundary condition is developed to attenuate the artificial boundary reflections generated in numerical simulation of the second-order elastic wave equation. The second-order equation can be described by displacement, which is more appropriate than the first-order one. Its PML condition conventionally needs to split the displacement into four parts, which occupies a large a- mount of memory and requires solving a third-order differential equation in time. As for the other choice, non-splitting PML method may be applied to the second-order equation, but it requires solving the dual integral in time. The new method can solve or simplity the above problems. Finally, a staggered-grid finite difference method with this PML condition is used to simulate an anisotropic media model and the results show that the method is efficient.