Sorptivity and liquid infiltration into dry soil

The sorptivity S quantifies the effect of capillarity on liquid movement in a porous material. For liquid infiltration into an initially dry material, S is a parameter that is contingent on both liquid and material properties as well as the maximum liquid content behind the infiltrating front, θm. Scaling analyses are used to derive a dimensionless, intrinsic sorptivity S∗ that is constant for different liquids, Miller-similar materials and different values of θm. The analyses confirm that S is dependent on β1/2, where β = cos ϕ is a measure of the wettability of the liquid. They also indicate a power law relationship between S and Se(av), the average liquid saturation behind the infiltrating front. Seventeen water and eleven Soltrol 220 horizontal infiltration experiments are reported in uniform, dry sand. Test results show that water is partially wetting in the sand. They also confirm that S∝Se(av)d, where d = 3.2 for the experimental conditions. The usefulness of a general, dimensionless Boltzmann variable is demonstrated to normalize infiltration profiles for the different liquids. An approximate method for sorptivity calculation is shown to provide an accurate estimate of S∗.