大地电磁二次函数插值的有限元法正演模拟

在矩形网格剖分情况下,讨论单元内采用二次函数插值的大地电磁二维有限元正演问题,推导出相应的计算公式,在解线性方程组求取各节点处的场值后,计算地表的电阻率和阻抗相位.通过与理论解析解及线性插值有限元法的计算结果的对比,证实了本文方法在网格剖分稀疏时,仍有高的计算精度,与线性插值法相比,采用放稀一倍的网格仍具有较高的计算精度,而两者的计算时间相差不多.

FINITE ELEMENT METHD USING QUADRATIC ELEMENT IN MT FORWARD MODELING

On the performance 0f the fihite element boniques in MT, linear ~ar elementhas already bo commonly utal' But it is difficult to achieve aanrate nUmerical solutionsbeause of the fast deCline 0f eleCtromagnehc wave with dePth and the wide freqUency sPcotrum. Band on the finite element method, however, we use quadratic interpolahon in a~gUlar element to solve 2-D magnet0telluric forward problem and an appropriatealgorithm is given here' By calculahng a few models set up t0 tal the method andcomParing the soluhon with the analyhcal soluh0n and the linear eleInen soluhon,we find that our method has many advantages over the llnear fort methd' Two mostprondnent advantageS of this mcthod are l' rngh aanracy' The resultS of 0ur method aremUC more accuratC than that of llnear method when we caculate the same model withsame mesh nodes. We ge reahve error of apparant resishvity less than O'l%, Whereaslinear one is more than l%' 2' bos caiculahng hme' To achieve the same amiracy, ourmethod is fastCf than linear method bouse we can use less meses'