Three-dimensional magnetotelluric forward modeling using structural-point EFGM and FEM coupling method

In this paper, the authors propose a method of three-dimensional (3D) magnetotelluric (MT) forward modeling algorithm based on the meshfree and finite element coupling method. The model is discretized by regular nodes in the central area, and the radial point interpolation method (RPIM) based on the global weakness is utilized to construct the meshfree shape function. The Governing equations in each background gird are solved by Gaussian integration. In the extended area where the points are sparsely distributed, to avoid the instability of the meshfree method, finite element method (FEM) with regular grids is used to solve the governing equation. Finally, the meshfree and finite element governing equations are coupled by the continuity of the field at the interfaces, and the direct solution technique is used to realize the 3D MT forward modeling. Numerical experiments of several typical electrical models are used to verify the effectiveness of the method.