关键词: 电性源, Cole-Cole模型, 有理逼近, 时域有限差分, 极化效应

Abstract: The time-domain electrical source electromagnetic detection method is an effective and fast method for detecting mineral resources. The polarization effect can lead to rapid attenuation of the electromagnetic response and even a symbol reversal phenomenon. In this paper, the Cole-Cole model is used to describe the polarization effect, and arbitrary fractional Cole-Cole models are rationalized by using the integer order rational approximation algorithm. Yee’s grid is used to divide the simulation area, and the three-dimensional numerical simulation of induction-polarization effect of electrical sources is realized based on the finite difference time domain (FDTD) method. The electromagnetic responses of three typical models, namely uniform half-space model, polarized half-space model and three-dimensional polarized body model, are numerically simulated. The results show that the electromagnetic response of  uniform half-space model is basically consistent with the analytical solution, and the relative error is less than 10%, which proves the feasibility of the three-dimensional numerical simulation method. The electromagnetic responses of  polarized half-space model and three-dimensional polarized body model both have negative responses in the late stage, which is consistent with the polarization theoretical results. 

Key words: electrical source, Cole-Cole model, rational approximation, finite-difference time-domain, induced polarization