非结构化网格有限元弹性波数值模拟

Finite-element numerical modeling of elastic wave on unstructured meshes

使用时域有限元法进行复杂地质构造下的弹性波数值模拟时,采用非结构化网格比结构化网格能更灵活地适应对复杂几何区域的空间离散。根据弹性波动力学模拟中的空间数值频散条件和显式时间更新稳定条件,本文对有限元网格的划分进行了专门优化,使网格单元尺寸随模拟区域的介质速度变化而变化。对双层介质模型的计算证明有限元网格尺寸随速度值变化能够同时保证计算效率和计算精度,对复杂构造模型的计算表明非结构化网格下的有限元方法能够适应复杂地质构造的地震波模拟。

When using finite-element time-domain method for the numerical modeling of complex geological structures,the unstructured meshes can be more efficiently adapted to the space-discretization for the complex geometries.In this paper,a specific optimization for the finite-element gridding is presented according to the numerical dispersion condition in space and the stability condition in explicit time-marching scheme,making the grid size varied versus the media speed of the simulation region.The calculation for two-layer model demonstrates that the variation of grid size versus velocity can guarantee the computational efficiency and precision contemporaneously.And the calculation for complex structure model demonstrates that the finite-element scheme with unstructured meshes can be adapted to the seismic wave modeling of complex geological structures.