基于系统迭代法的线源瞬变电磁近区正演模拟

Transient electromagnetic forward modeling for near region of a line source based on the method of system iterative

积分方程法求解大型稀疏矩阵制约线源近区三维瞬变电磁正演模拟的速度,采用系统迭代法,把整个异常体区域看成一个系统,每个块状异常体在各自区域内形成子系统,单独处理各个异常体,并建立子系统间的关系,从而得到整个系统的值,这样不仅节省了内存和计算时间,而且降低了离散矩阵的条件数,提高计算速度和精度。通过与解析解的对比证明了该方法的正确性,简单和复杂三维体的二次水平电场和垂直磁场瞬态响应计算结果表明:①二次水平电场值反映了三维异常体的电性特征,同时其极值对应异常体的左右边界;②垂直磁场响应反映了异常体的纵向分辨率,曲线随偏移距增加而变缓。

The integral equation method for solving large sparse matrix controls 3D transient electromagnetic forward modeling for near region of a line source in speed.It is not only saving memory and computing time,but also reducing the discrete matrix condition number for improving the calculation speed and accuracy by the method of system iterative that we take the anomaly structure as a whole system,the substructure from subsystems within themselves and solve the various abnormal body alone to establish the relationship between the subsystem,thus get the whole system.This method is correct by comparison with the analytical solution.The secondary horizontal electric field and vertical magnetic field transient response calculation results of the simple and complex three-dimensional body show that：the secondary horizontal electric field value reflects the electrical char-acteristics of three-dimensional abnormal body,its extremun corresponding to left and right boundary of the abnormal body ;vertical magnetic field response reflects the longitudinal resolution of abnormal body,curves increasing with offset slowly.