A rotated staggered grid fi-nite-difference with the ab-sorbing boundary condition of a perfectly matched layer  

作　　者：CHEN Hao WANG Xiuming ZHAO Haibo 

机构地区：[1]Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080 China [2]CSIRO Petroleum, ARRC, Technology Park, Bentley, WA 6102, Aus tralia

出　　处：《Chinese Science Bulletin》2006年第19期2304-2314,共11页

摘　　要：A rotated staggered grid finite-difference (FD) method with a perfectly matched layer (PML) method is proposed for numerically solving elastic wave equations in inhomogeneous elastic and poroe- lastic media. Compared with a standard staggered- grid FD, the former has the advantage over the latter in that its physical variables need only to be defined at two locations. In the rotated staggered grid, stress and strain components (or particle velocity and dis- placement components) are defined at elementary cell centers, and the velocity or displacement com- ponents (or the stress and strain components) are defined at vertexes. In this way, no elastic moduli need to be interpolated or averaged. Numerical re- sults from the proposed method have been compared with the standard staggered FD method. The results are in good agreement with each other. Our numeri- cal results show that the proposed algorithm can handle much stronger impedance contrast. This is especially true when simulating fractured medium filled with fluids such as water or gas without giving special treatment. On the other hand, the imple- mented PML absorbing boundary condition works well in efficiently reducing reflected waves from the artificial interfaces. It generates almost no reflection at artificial interfaces with a boundary of PML thick- ness of half a wavelength. Our theoretical analysis and numerical tests proved that the PML absorbing algorithm in the rotated staggered grid is almost identical to those in the standard staggered grid. In this paper, we also presented all of the formulations of the PML implementation and modeling examplesA rotated staggered grid finite-difference （FD） method with a perfectly matched layer （PML） method is proposed for numerically solving elastic wave equations in inhomogeneous elastic and poroelastic media. Compared with a standard staggeredgrid FD, the former has the advantage over the latter in that its physical variables need only to be defined at two locations. In the rotated staggered grid, stress and strain components （or particle velocity and displacement components） are defined at elementary cell centers, and the velocity or displacement components （or the stress and strain components） are defined at vertexes. In this way, no elastic moduli need to be interpolated or averaged. Numerical results from the proposed method have been compared with the standard staggered FD method. The results are in good agreement with each other. Our numerical results show that the proposed algorithm can handle much stronger impedance contrast. This is especially true when simulating fractured medium filled with fluids such as water or gas without giving special treatment. On the other hand, the implemented PML absorbing boundary condition works well in efficiently reducing reflected waves from the artificial interfaces. It generates almost no reflection at artificial interfaces with a boundary of PML thickness of half a wavelength. Our theoretical analysis and numerical tests proved that the PML absorbing algorithm in the rotated staggered grid is almost identical to those in the standard staggered grid. In this paper, we also presented all of the formulations of the PML implementation and modeling examples in elastic, poroelastic, and anisotropic media.

关 键 词：有限差 微电极测井 PML 完全匹配层 

分 类 号：P631.3[天文地球—地质矿产勘探]