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近年来,国内外学者对瞬变电磁法2.5维有限单元正演模拟进行了大量的研究.在前人研究的基础上给出了矩形回线源瞬变电磁法2.5维有限差分正演模拟算法.从磁场垂直分量满足的扩散方程入手,推导了瞬变电磁法2.5维有限差分正演计算的差分方程;通过正余弦变换、Gaver-Stehfest变换、反傅氏变换等数值方法求解了均匀半空间矩形回线源激发的波数域瞬变场,作为初始条件;推导了波数域磁场向上延拓的公式,作为地空边界条件.最终建立了瞬变电磁法2.5维有限差分正演模拟算法.通过与解析解、有限元数值解的对比以及对典型模型的正演模拟,证明了算法的正确性与有效性.
In recent years, scholars at home and abroad have done a great deal of research on forward modeling of 2.5-D finite element of transient electromagnetic method.On the basis of previous studies, a 2.5-D finite difference forward modeling algorithm for rectangular loop source transient electromagnetic method Starting from the diffusion equation that the vertical component of the magnetic field satisfies, a differential equation of 2.5-D finite-difference forward modeling of the transient electromagnetic method is deduced. Numerical methods such as cosine transform, Gaver-Stehfest transform and inverse Fourier transform are used to solve the problem of uniform half-space Rectangular wave source excited wave number domain transient field, as the initial conditions; derived wave number domain upward magnetic field expansion formula as a ground-air boundary conditions.Finally established a transient electromagnetic 2.5-D finite difference forward modeling algorithm by Compared with analytic solution, numerical solution of finite element method and forward modeling of typical model, the correctness and validity of the algorithm are proved.