Finite Element Modeling Of 2.5D TEM With A Central Loop Using Unstructured Meshes

Transient Electromagnetic Method (referred to as TEM) belong to the time domain electromagnetic method,it's a new geophysical exploration method developed in recent years. Currently, TEM is low levels of data interpretation, basically stuck in one-dimensional stage, two-dimensional and three-dimensional inversion interpretation techniques for the real practical use is still a considerable distance. In geophysics, forward modeling is the basis of data processing and data inversion, we need to first study the forward problem.2.5-dimensional numerical simulation of transient electromagnetic method that is one of difficult problems in geophysical calculation and not yet properly solved, but is valuable in practical.This article from the Maxwell equations and deduced transient electromagnetic anomaly field in the 2.5-dimensional problem set solutions of partial differential of the problem, boundary conditions, functional extrema, etc.; and focus on implementation of several key Question that's have a major impact on the program:Laplace inverse transform, inverse Fourier transform and the calculation of non-direction component. Language using program matlab accomplish 2.5 dimensional finite element program, and examined the algorithm through horizontal layered models' numerical simulation, the paper calculated the rectangular back to the line in the horizontal surface layer geoelectric model of the transient electromagnetic response of incentives, analysis and comparison of the layered structure of several anomaly field of media and the total transient electromagnetic field response characteristics.For the previous use structured mesh's shortcomings in the transient electromagnetic 2.5-D problem forward, this strategy adopted unstructured mesh to achieve the meshing. Unstructured mesh generation by using the commonly used method of Delaunay triangulation method, and realized the subdivision of complex geological model, the range of applications of existing 2.5-D transient electromagnetic forward algorithm has been expanded. With traditional structured mesh generation as compared to the unstructured grid used in this paper partition means to achieve the same accuracy in the case of the grid, the number of nodes and cells were significantly reduced, to reduce the unnecessary computation nodes.