P. Ustohal et al., MEASUREMENT AND MODELING OF HYDRAULIC CHARACTERISTICS OF UNSATURATED POROUS-MEDIA WITH MIXED WETTABILITY, Journal of contaminant hydrology, 33(1-2), 1998, pp. 5-37
Citations number
41
Categorie Soggetti
Water Resources","Environmental Sciences","Geosciences, Interdisciplinary
The spatial distribution of the solid grain's wettability strongly inf
luences the phase-interconnection, phase-flow and solute transport in
unsaturated porous media. Non-uniform wetting conditions can arise in
soils and aquifers from natural or anthropogenic impacts. In this stud
y, a water-air system in porous media consisting of several types of g
ranular materials is considered. A conceptual model for pressure-wise
estimation of water saturation and relative unsaturated hydraulic cond
uctivity of such materials is proposed. The model uses the boundary wa
ter retention curves and corresponding wetting angles of the pure comp
onents of the mixture as the input parameters. The approach is based o
n simplified statistical and geometrical assumptions for describing th
e mixed porous material and its capillary behavior. In the experimenta
l part of this study, three materials with different wetting angles (q
uartz sand, silanized quartz and teflon grains) were used both as pure
and as homogeneously mixed packings to conduct experiments with a wat
er-air system in short columns under well-controlled laboratory condit
ions. The hydraulic characteristics were determined for packings with
various mixing ratios. The non-uniform matrix wettability was found to
strongly influence the water retention behavior of the packings, wher
eas its impact on the water-saturation-dependent hydraulic conductivit
y was weak. The measured data are compared to model predictions. The r
esults show that the model is capable of providing good qualitative es
timates of both the boundary water retention curves and the curves of
the relative hydraulic conductivity for all investigated materials. (C
) 1998 Elsevier Science B.V. All rights reserved.