Non-Fickian tracer transport in porous media

Diffusion processes have traditionally been modeled using the classical diffusion equation. However, as in the case of tracer transport in porous media, significant discrepancies between experimental results and numerical simulations have been reported in the literature. Therefore, in order to describe such anomalous behavior known as non-Fickian diffusion, some authors have replaced the parabolic model by continuous random walk models, which have been shown to be very effective. Integro-differential models have been also proposed to describe non-Fickian diffusion in porous media. The aim of this paper is to compare the ability of these classes of models to capture the dynamics of tracer transport in porous media