Numerical simulation of seismic waves in transversely isotropic media based on orthogonal body-fitted grids
Liu Zhi-qiang,*, Li Gang-zhu, Huang Lei, Niu Xing-guo, Zhang Xiao-meng, Gao Cheng
1. Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Inner Mongolia Key Laboratory of Ecohydrology and High Effi cient Utilization of Water Resources, Hohhot 010018, China;
2. Autonomous Region Collaborative Innovation Center for Integrated Management of Water Resources and Water
Environment in the Inner Mongolia Reaches of the Yellow River, Hohhot 010018, China;
3. Inner Mongolia Nonferrous Geology and Mining (Group) Geophysical Exploration Co., Ltd., Hohhot 010010, China;
4. School of Resources and Environmental Engineering, Inner Mongolia University of Technology, Hohhot 010010, China
Abstract：
In conventional finite difference numerical simulation of seismic waves, regular grids in Cartesian coordinates are used to divide the calculated region. When simulating seismic wave fi elds under an irregular surface, such grids are unsuitable to realize the free boundary condition. They also easily generate false scattered waves at the corners of the grids owing to the approximation of the stepped grids. These issues affect the simulation accuracy. This study introduces an orthogonal body-fitted grid generation technique in computational fluid dynamics for generating grids in transversely isotropic (TI) media under an irregular surface. The first–order velocity–stress equation in curvilinear coordinates is calculated using the optimized nonstaggered grids finite difference method. The point oscillation generated by the nonstaggered grids difference is eliminated by selective filtering. The orthogonal body-fitted grids can accurately describe the irregular surface. Further, the orthogonality of the grids allows the implementation of free boundary conditions without complicated coordinate transformation and interpolation operations. Numerical examples show that the numerical solutions obtained by this method agree well with the analytical solutions. By comparing the simulation results of the proposed method with those of the regular grid difference method, the proposed method can eff ectively eliminate the false scattered waves caused by the stepped grids under the condition of the same grid spacing. Thus, the accuracy of the numerical simulation is improved. In addition, the simulation results of the three-layer TI media model on an irregular surface show that the proposed method is also suitable for complex models.
作者简介: Liu Zhi-qiang, Lecturer, graduated from Jilin University with a PhD in Earth Exploration and Information Technology. He is currently a lecturer in the Water Conservancy and Civil Engineering in Inner Mongolia Agricultural University. His mian interests are theory and technique of forward and inversion of seismic wave fi eld and microtremor exploration.
. Numerical simulation of seismic waves in transversely isotropic media based on orthogonal body-fitted grids[J]. APPLIED GEOPHYSICS, 2025, 22(2): 408-421.
2025, Vol. 22 
