Correlation functions for inhomogeneous magnetic field in random media with application to a dense random pack of spheres

In porous media subject to applied magnetic field, the internal field arises out of susceptibility contrast of the constituents. We have examined the spatial inhomogeneity of the internal fields in a random pack of spheres using numerical computation. We find that the pair-correlation function of the internal field (K₂) is a close approximation to the structure factor of the material, thus K₂ can be used to characterize pore geometry. The magnetic length scale Λ_M exhibited in K₂ is shown to be related to the fluid transport in the medium.