Induced Polarization of Metal Grains: Simulations of Three‐Dimensional Electric Fields

Abstract

Induced polarization (IP) method is one of the geophysical methods that utilizes polarization of subsurface materials. This method is very sensitive to the presence of (semi) conducting materials. Previous studies revealed the underlying mechanisms of metal polarization in simple geometry. However, there is a gap between such studies and the conditions in geological materials. To fill the gap, I have established the simulation method for studying the polarization of metal grains in a three‐dimensional field using the open‐source computational‐fluid‐dynamic software OpenFOAM. The three‐dimensional view of the surface potential distribution on a metal grain clarified how polarization is induced while varying geometrical constrictions. I varied the channel size, the orientation of the anisotropic grain, the elongation of the grain, and the distance of two grains. The results include: (a) a less decay of imaginary potential over distance for shorter or narrower channel, enhanced polarization in narrower channel and reduced polarization in shorter channel, (b) shift of the position of maximum imaginary potential over frequency on the surface of the oriented anisotropic grains, (c) higher peak frequency and larger polarization locally at the edge of the grains for elongated grains, and (d) enhancement of polarization by interaction of nearby grains. The underlying mechanisms were examined for each case. In addition, relationships between each scenario in my simulation and the subsurface environment were discussed. My successful implementation of the simulation for metal grains may be applied to improve the modeling, interpretation, and laboratory experimental setup.