outlet concentration to 0. The effective diffusivity is determined by solving Fick's law with the flow rate determined from the Fickian diffusion simulation. The effective diffusion coefficient determined through the simulation is then used to calculate the tortuosity factor of the pore phase. Twopoint correlations can be measured by counting pair-wise occurrences of two phases and dividing by an expected random distribution. However, iterating over the entire microstructure using this process is computationally expensive. It is known that the power spectrum of a density distribution can be derived from the Fourier transform of its two-point correlation function . Hence, in this implementation the fact that the autocorrelation of a density distribution can be computed as an FFT is used to obtain an accurate estimation of the power spectrum. The power spectrum is then mathematically inverted to obtain the two point correlation function of the phases of interest . This