一种新的弹性波数值模拟吸收边界条件

A new numeric simulating absorbing boundary condition of elastic wave

在弹性波方程有限差分波场数值模拟中,由于计算模型的限制,不可避免地导致很强的人为边界反射的出现。为了使计算得到的边界波场值更接近真实的边界波场值,在波场数值模拟中人们利用边界条件来减少来自计算区域边界的人为反射能量。与声波吸收边界条件相比,弹性波边界条件要复杂得多,到目前为止弹性波边界条件算法研究仍然是该领域的一个重要课题。本文借鉴Clayton等处理吸收边界反射的思想,从弹性波波动方程出发,提出了一种新的在各向同性介质中进行有限差分弹性波场数值模拟的吸收边界条件。波场计算表明:该方法计算量小、应用简单、能有效地减少来自模型边界的反射波场,其计算效率与Clayton等处理吸收边界条件所花费的时间相当。

In finite difference numeric simulation of wavefield for elastic wave equation,limited in computational model,appearing the man-made boundary reflection is inevitable. In order that the com-puted boundary wavefield more approaches thetrue boundary wavefield,the boundary conditions are often used to reduce the man-made reflection energy coming from computational boundary in numeric simulation of wavefield. In comparison with acoustic absorbing boundary condition,the elastic wave boundary condition is more complicated and the study on algorithm of elastic wave boundary condition has been still an important subject in the field until now. In the aid of the Clayton's idea processing absorbing boundary reflections and starting from elastic wave equation,the paper presented a new absorbing boundary condition of finite-difference numeric simulating the elastic wavefield in homogeneous medium. The wavefield computation showed that the algorithm is characterized by small computational effort,simple application and being able to effectively reduce the reflection wavefield from model condition,in which the computational efficiency is equivalent to the time consumed in processing absorbing boundary condition by Clayton et al.