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.