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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。
Boundary reflection inevitably occurs in the numerical simulation of seismic wave field. Generally, absorbing boundary conditions are used to suppress artificial boundary reflection. The commonly used Split Perfect Matching Layer (PML) boundary conditions require special treatment at the boundaries, especially in the three-dimensional case, the variable needs to be split into three components, which increases the computational time and memory consumption of the numerical simulation. Compared with the splitting PML absorption boundary conditions, the hybrid absorption boundary conditions (HABC) are easy to implement, the calculation is small and the absorption effect is good, which can improve the computational efficiency of the three-dimensional wave equation numerical simulation. In this paper, the mixed absorption boundary conditions based on the first-order Higdon one-way wave equation are developed from two-dimensional domain to three-dimensional. A hybrid absorption boundary condition suitable for three-dimensional elastic wave numerical simulation is proposed. The results of three-dimensional numerical simulation of uniform model and complex model show that the hybrid absorption boundary conditions have the advantages of high efficiency and good absorption effect compared with the traditional perfect matching boundary conditions.