Hybrid absorbing boundary condition for threedimensional elastic wave modeling

三维弹性波正演模拟中的混合吸收边界条件（英文）

Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer （PML） boundary condition requires special treatment for the absorbing zone, and in three-dimensional （3D） modeling, it has to split each variable into three corresponding variables, which increases the computing time and memory storage. In contrast, the hybrid absorbing boundary condition （HABC） has the advantages such as ease of implementation, less computation time, and near-perfect absorption; it is thus able to enhance the computational efficiency of 3D elastic wave modeling. In this study, a HABC is developed from two-dimensional （2D） modeling into 3D modeling based on the I st Higdon one way wave equations, and a HABC is proposed that is suitable for a 3D elastic wave numerical simulation. Numerical simulation results for a homogenous model and a complex model indicate that the proposed HABC method is more effective and has better absorption than the traditional PML method.

地震波场数值模拟中不可避免地会出现边界反射,一般采用吸收边界条件以压制人工边界反射。目前常用的分裂式完全匹配层(PML)边界条件需要在边界处进行特殊处理,尤其是在三维情况下需要将变量分裂为三个分量,增加了数值模拟的计算时间和内存占用量。与分裂式PML吸收边界条件相比,混合吸收边界条件(HABC)具有易于实现、计算量小和吸收效果好等优点,可以提高三维波动方程数值模拟的计算效率。本文将基于一阶Higdon单程波方程的混合吸收边界条件从二维计算域发展到三维,提出了适用于三维弹性波数值模拟的混合吸收边界条件。均匀模型以及复杂模型的三维数值模拟结果表明,混合吸收边界条件与传统的完全匹配层边界条件相比,具有效率高、吸收效果好的优势。