1. College of Information and Electronic Engineering, Hunan City University, Yiyang, Hunan 413002, China; 2. School of Geosciences and Info-Physics, Central South University, Changsha, Hunan 410083, China; 3. Key Laboratory of Computing and Stochastic Mathe-matics(School of Mathematics and Statistics, Hunan Normal University), Changsha, Hunan 410081, China; 4. State Key Laboratory of Nuclear Resources and Environment(East China University of Technology), Nanchang, Jiangxi 330013, China
Abstract:Traditional 3D CSAMT forward modeling has disadvantages such as source singularity and infinite boundaries. This paper proposes a 3D CSAMT forward modeling algorithm based on an equivalent source. It is fast and accurate for forward modeling of electric dipole sources. Firstly, accurately simulate the horizontal electric dipole source by calculating the electromagnetic field at the grid nodes in a certain range near the source. Secondly, replace the traditional cut-off boundaries with infinite elements, and implement finite element-infinite element coupling and paralleling to directly get fast and accurate 3D CSAMT solutions on an equivalent field source. The algorithm has been proved correct on a uniform half-space model. Finally, the optimal range of source equivalent simulation was studied based on the skin depth formula. Numerical results show that the best equivalent range of source shouldn't be less than 1.5 times of the skin depth.
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