完全匹配层吸收条件下的交错网格弹性波模拟

Staggered grid elastic wave simulation with perfectly matched layer absorbing condition

弹性波既包含纵波,又包含横波,同声波相比其与地震波更为相近,所以利用弹性波进行数值模拟更接近实际。本文基于速度-应力弹性波动方程进行有限差分数值模拟,采用交错网格的差分格式,将速度和应力分布于两套网格上。根据需要采用不同阶数的时间和空间差分精度,在保证结果精度的前提上,提高计算效率。为了排除虚假反射的影响,采用完全匹配层吸收条件,建立垂直阶梯模型进行数值模拟,得到对应的波场快照和单炮记录。数值结果分析表明,完全匹配层也可以很好地吸收人工边界产生的虚反射现象。综合利用这两者可以更好地探究弹性波的传播规律,有利于进行精确的数值模拟。

Elastic wave contains both compressional and shear waves,compared with sound waves with the seismic wave is more similar,So using elastic wave numerical simulation is more realistic. This article is based on speed- stress elastic wave equation finite difference numerical simulation,using staggered grid finite difference format,makes the velocity and stress distribution on the two sets of grid. According to the need to adopt different order number of time and space difference accuracy,on the premise of ensure accuracy of the results,improve the efficiency of calculation. In order to eliminate the effects of false reflection using perfectly matched layer absorbing condition,establishing numerical simulation of vertical ladder model,get the corresponding wave field snapshots and single shot records. Numerical results show that perfectly matched layer can well absorb the artificial boundary of ghost phenomenon. Comprehensive utilization of the two can better into elastic wave propagation law,is helpful to precise numerical simulation.