We have developed an overset-grid algorithm to simplify the difficulty of curvilinear grid (CG) generation and increase the computational efficiency for seismic wavefield modeling by using the finite-difference method in areas with complex surface topography. The overset grid comprises a Cartesian grid block and an approximately orthogonal CG block. The Cartesian grid covers most of the simulation domain, whereas the CG discretizes the near-surface topography. The Cartesian grid and the CG overlap each other arbitrarily. We use sixth-order explicit Lagrangian interpolation to exchange data between the Cartesian grid and the CG, which is shown to be sufficiently accurate. We also find that spatially smoothing the source term is important for reducing strong artificial reflections when the source is near the overlapping zone. Finally, numerical tests are performed to verify that the proposed overset grid is well suited for effective numerical simulation of seismic wave propagation.

中文翻译：

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一种模拟复杂自由表面形貌介质中弹性波传播的重叠网格有限差分算法

我们开发了一种重叠网格算法，通过在具有复杂表面地形的地区使用有限差分方法来简化曲线网格 (CG) 生成的难度并提高地震波场建模的计算效率。重叠网格包括笛卡尔网格块和近似正交的CG块。笛卡尔网格覆盖了大部分模拟域，而 CG 离散化了近地表地形。笛卡尔网格和CG任意重叠。我们使用六阶显式拉格朗日插值在笛卡尔网格和 CG 之间交换数据，这被证明是足够准确的。我们还发现，当源靠近重叠区域时，空间平滑源项对于减少强人工反射很重要。最后，