【摘要】 三维地震波数值模拟中的吸收边界如果采用镶边处理(如最佳匹配层吸收边界条件(PML)或阻尼吸收边界条件),会大幅度增加计算量和计算时间,若增加旁轴近似阶数,则会增加数值实现的复杂度,甚至会导致计算过程的不稳定。为解决上述问题,提出优化的三维声波旁轴近似吸收边界条件,并做了相应的理论推导和数值分析,只需合理地调节加权因子,就可拓宽边界处的完全吸收角度,且其反射系数误差很小。数值实例表明,该方法不增加计算空间,算法简单且易于实现,能够获得比常规旁轴近似吸收边界条件更好的边界吸收效果,是一种有效的三维地震波数值模拟吸收边界条件。更多还原

【Abstract】 Computational cost increase greatly in numerical simulation of 3-D seismic waves if padding processing such as PML or damping absorbing boundary condition is adopted in handling of absorbing boundary conditions.These algorithms of the simulation are complicated,even become instable if increasing the order of paraxial approximation.Optimized dual absorbing boundary condition was proposed and formulae were derived.Theoretical analysis showed that if proper weighting factor is used,the complete absorbing angle is enlarged at the boundary and the errors in reflectance are small.Numerical examples showed that the proposed method does not increase the computational cost.It is easy to implement and yields better results compared to conventional paraxial approximation.更多还原