Heterogeneous Anisotropic Elastic Finite Difference Method for Irregular Grid

By

Weitao Sun¹, Huizhu Yang¹

(1) Tsinghua University, Dept. of Engineering Mechanics, Beijing, China

 This paper presents a new finite-difference (FD) method for spatially irregular grids to simulate elastic wave propagation in heterogeneous anisotropic media. It is very simple and costs less computing time. Complicated geometrical structures like low-velocity thin layers, cased borehole and nonplanar interfaces are treated on a fine irregular grid. Unlike multi-grid scheme, this method has no interpolation between the fine and coarse grid and all grids are computed at the same spatial iteration. Planar or nonplanar surfaces, including underground cavities and cased borehole, are treated in a way similar to regular grid points but with different elastic parameters and density. The Higdon absorbing boundary condition is adopted to eliminate boundary reflections. Numerical simulations show that this method has satisfactory stability and accuracy. It is more efficient in simulating wave propagation in heterogeneous anisotropic media than conventional method using regular rectangular grid of equal accuracy. The method can be easily extended to unstructured grid and three dimension problems.