Computational experiments on three-dimensional molecular diffusion in porous media

Estimations of apparent diffusion coefficients usually consist of curve-fitting the output of 1-D models to experimental laboratory-measured data from porous aggregates shaped in different forms. In this research, a computational exploration is presented on the alternative use of three-dimensional models for the same purpose. The outputs of the 3-D models were compared to results generated by one-dimensional formulations. The comparison showed that there are significant discrepancies in the concentration values output by the models. Percent differences ranging from 30 to 90% were calculated. Those different estimations suggest that different values of the apparent diffusion coefficient may be obtained if the threedimensional solution of the diffusion equation would be used to match experimental results.