线源二维时间域电磁响应的有限差分解

FINITE DIFFERENCE CALCULATIONS OF TRANSIENT TIME DOMAIN ELECTROMAGNETIC FIELD OF A TWO DIMENSIONAL EARTH FOR A LINE SOURCE OF CURRENT EXCITATION

本文以ＫｕｏａｎｄＣｈｏ（１９８０）和ＯｒｉｓｔａｇｌｉｏａｎｄＨｏｈｍａｎｎ（１９８３）工作为基础，对时间域中直接求解无限长电流源激发下任意二维电阻率分布的麦克斯韦方程的有限差分方法进行了重新研究，提出了一种改进方法，这种方法的独特之处在于用变化方向法把二维问题化为一系列一维问题来求解，并保留了前人在地－空边界使用地表向上延拓的边界条件以避免求空气中的场的处理技术，从而节省了计算机内存、简化了计算方法和提高了运算速度。文章计算了多个模型的数值解。

According to the works of Kuo and Cho (1980) and Oristaglio and Hohmann (1984), a modified finite difference approach technique was presented in this paper for solving time stepping Maxwell's equations of an arbitrary two dimension earth excited by an infinite line of current located on the surface. In this method, two dimension was reduced to a series of one dimension by the methodology of transfering direction, and the previous technique was retained in which the boundary condition of an upward continuation at the earth air interface was applied to avoid finding the solutions of the air layer in the grid. Thus the computer' memory was saved, calculating method was simplified and calculation can speed up. Solutions of various models showed that this method has great calculation precision.