Reduction of Electromagnetic Reflections in 3D Airborne Transient Electromagnetic Modeling: Application of the CFSPML in Source-free Media
Reduction of Electromagnetic Reflections in 3D Airborne Transient Electromagnetic Modeling: Application of the CFSPML in Source-free Media
复制标题
3D 机载瞬态电磁建模中电磁反射的减少：CFSPML 在无源介质中的应用
DOI：
10.1155/2018/1846427
复制
发表时间：
2018
影响因子：
1.5
通讯作者：
Shanshan Guan
中科院分区：
文献类型：
--
作者：
Yanju Ji;Xuejiao Zhao;Jiayue Gu;Dongsheng Li;Shanshan Guan
为了解决有限差分时域（FDTD）网格终止引起的电磁反射问题，我们将复频移完美匹配层（CFS - PML）应用于无源介质中的机载瞬变电磁（ATEM）建模。为了实现CFS - PML，改进了两个重要方面。首先，我们的方法采用无源麦克斯韦方程组作为控制方程，并引入散度条件，从而推导出关于CFS - PML形式的麦克斯韦第三方程的离散形式。其次，由于我们的方法采用了非均匀时间步长，因此提出了基于非均匀时间步长的卷积项组成的递推公式。通过使用具有不同电导率的均匀半空间模型计算电磁响应，验证了所提出的方法。结果表明，CFS - PML可在后期降低60 dB的相对误差。此外，该方法也适用于三维异常模型；结果表明，该方法可以有效地减少反射，大大提高了对异常体的识别。因此，CFS - PML对无源介质中的ATEM建模具有很好的意义。
To solve the problem of electromagnetic reflections caused by the termination of finite‐difference time‐domain (FDTD) grids, we apply the complex frequency‐shifted perfectly matched layer (CFS‐PML) to airborne transient electromagnetic (ATEM) modeling in a source‐free medium. To implement the CFS‐PML, two important aspects are improved. First, our method adopts the source‐free Maxwell’s equations as the governing equations and introduces the divergence condition, consequently, the discrete form of Maxwell’s third equation is derived with regard to the CFS‐PML form. Second, because our method adopts an inhomogeneous time‐step, a recursive formula composed of convolution items based on a nonuniform time‐step is proposed. The proposed approach is verified via a calculation of the electromagnetic response using homogeneous half‐space models with different conductivities. The results show that the CFS‐PML can reduce a 60 dB relative errors in late times. Moreover, this approach is also applied to 3D anomalous models; the results indicate that the proposed method can reduce reflections and substantially improve the identification of anomalous bodies. Consequently, the CFS‐PML has good implications for ATEM modeling in a source‐free medium.