Two-dimensional forward modeling of magnetotelluric field based on GLC polynomial spectral element method
The two dimensional forward modeling of magnetotelluric(MT)fields based on the Gauss-Lobatto-Chebyshev(GLC)basis function spectral element method is put forward to improve the accuracy and efficiency of the numerical simulation of magnetotelluric fields.Under the guidance of this method,we derive the 2D MT boundary value problem and then transform it into the integral weak form through Galerkin weighted residual method.At last,we discretize the global problem using GLC interpolation basis functions and obtain MT fields after solving the large-scale sparse linear equations system using the Pardiso solver,successfully numerically simulating it.To improve the computational efficiency of the numerical simulation,we adopt a variable density regular grid generation technique.This technique,by using finer grids in electrically complex areas and coarser grids in electrically homogeneous areas,can reduce computational time.In addition,parallel processing of mul-tiple frequencies is achieved using OpenMP programming.Numerical simulation results of a one-dimensional layered media model validate the correctness and accuracy of the proposed algorithm,showing a higher accuracy of the GLC polynomial spectral element method compared with GLL.Forward modeling based on the GLC polynomial spectral element method,finite difference method,and triangular mesh finite element method is con-ducted for the COMMEMI 2D-1 model and the terrain model,and the comparison results show that the GLC method has a higher accuracy and less grid dependence.
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