论文详情
弹性波数值模拟中分裂格式的完全匹配层吸收边界(SPML)难以吸收与边界接近平行传播的地震波,并会产生数值噪声,降低了地震波模拟的精度。针对此问题,提出了复合吸收边界条件,将SPML边界条件与海绵吸收边界条件组合成边界的内外层,实现了对与边界接近平行传播地震波的有效吸收。针对数值噪声沿边界传播的特点,对复合边界中的海绵边界吸收系数进行了改进,提高了海绵边界对平行于边界方向传播的地震波的衰减能力,进一步提高了对入射至边界处地震波的吸收效果。数值测试结果显示,不论对简单速度模型还是复杂速度模型,复合吸收边界对地震波的吸收效果优于常规SPML边界的吸收效果,且不会产生明显的数值噪声。
In pseudo-spectral elastic wave modeling,the conventional split perfectly matched layer (SPML) is less effective in attenuating seismic waves that propagate almost parallel to the boundary and generates numerical noise,reducing the numerical simulation accuracy.Here,we propose a composite absorbing boundary (CAB) by adding a sponge-absorbing boundary layer outside the SPML absorbing boundary to attenuate the unabsorbed seismic waves through the SPML boundary.We modified the sponge boundary absorption coefficient in the CAB to avoid numerical noise generation.The numerical experiments show that the CAB has a higher attenuation capability than the conventional SPML for seismic waves traveling parallel to the boundary,and no significant noise is generated around the boundary.Since the proposed CAB adds an absorption layer outside the original PML and does not introduce additional complex mathematical transformations,it can be easily applied to other types of numerical simulations of seismic waves,such as finite difference and finite element methods.
国家科技重大专项(2016ZX05006002-001)、国家自然科学基金重点项目(41230318)、山东省自然科学基金(ZR2014DM006)和教育部留学回国人员科研启动基金(教外司留［2015］1098号)共同资助。