A numerical experiment on pore size, pore connectivity, water retention, permeability, and solute transport using network models

Network models are idealized geometrical representations of porous media. They allow the simulation of effective hydraulic properties and of solute transport for well-defined porous structures. In this paper, the relation between pore structure and effective properties is studied using a network model which can be adjusted to predefined pore-size distributions and pore topologies. I show that pore topology can be adjusted such that quite different pore-size distributions lead to essentially identical water retention curves. This puts into question the common interpretation of the retention curve as being indicative of the pore-size distribution. However, I also found that both the hydraulic conductivity and the dispersion of a solute depend on the water retention curve and not on the particular combination of pore-size distribution and topology which make it up. This corroborates the widely used approach of inferring relative permeabilities from water retention data.