可控源电磁三维频率域有限元模拟

Controlled source electromagnetic 3-D modeling in frequency domain by finite element method

本文采用电磁场的磁矢量位和电标量势,将Maxwell方程组化为位势的类似于Helmholtz型方程,并引入罚项及稳定化方法克服了电磁三维有限元算法中的伪解及数值不稳定性;采用人工边界把计算区域局域化,将均匀半空间中水平电偶极子源产生的位势值作为人工边界上的第一类边界条件以表示源的作用,减少了实际的计算区域.理论模型和复杂模型的计算结果均表明,可控源电磁三维有限元数值模拟给出了稳定、可靠的电磁场分布.

Magnetic vector potential and electric scalar potential of electromagnetic field are employed in this paper and the Maxwell＇s equations can be transformed into partial differential equation of the potential, which is akin to Helmholtz equation. A penalty term is added to eliminate the spurious solution and a stabilization method is used to overcome the numerical instability in 3-D electromagnetic finite element （FE） simulation. An artificial boundary delimiting a relatively small area is adopted to reduce computation consumption. The first-kind boundary condition is employed at the artificial boundary, which is the value of potential excited by a horizontal dipole source in homogeneous half space. Our results show that 3-D controlled source electromagnetic FE simulations for theoretical and complicate models in this paper give stable and trustworthy solutions of electromagnetic field.