Abstract:

It is difficult to deal with the irregular boundary using finite-difference method in the DC electric field numerical modeling including surface topography. To solve this problem, we introduce a coordinate transformation idea that transforms curved surface into horizontal topography and realize a new finite-difference method basing on the transform. We firstly transform the basic equations and boundary conditions of DC electric field from physical space to computation space, and then resolve the DC fields in computation space using finitedifference method. Finally, we retransform the computation results from computation space into physical space by coordinate mapping. Accuracy analysis and numerical tests show that the computation error congregates around the source, and the average relative error is less than 1% if the source is close enough to the irregular surface. Therefore, the new method has high accuracy, and the computation results can reveal the distribution characteristics of DC electric field and apparent resistivity including surface topography.

Key words: surface topography, DC electric field, coordinate transformation, finite-difference