HR: 1340h
AN: H33A-1367    [Abstracts]
TI: Estimating Film Flow Behavior in a Crushed Volcanic Tuff
AU: * Jansik, D P
EM: jansikd@onid.orst.edu
AF: Oregon State University, Department of Geoscience, 104 Wilkinson Hall, Corvallis, OR 97331 United States
AU: Wildenschild, D
EM: wildend@geo.oregonstate.edu
AF: Oregon State University, Department of Geosciences and Department of Civil, Construction and Environmental Engineering, 104 Wilkinson Hall, Corvallis, OR 97331
AB: Current understanding of interfacial areas and flow in unsaturated soil does generally not account for liquid films that form on subsurface porous media at low saturations. According to Tuller and Or [1999] the presence and size of liquid films are controlled by molecular, electrostatic, structural and adsorptive forces, the sum of which is equated to the disjoining pressure. Because the behavior of these films is complex and difficult to measure, they are often ignored. A thorough understanding of the influence of these films on available interfacial area, meniscus curvature development, and permeability is vital for addressing flow and transport problems that take place in the low saturation range such as those encountered in irrigated agriculture, enhanced oil recovery, and environmental problems in arid settings. Using a two dimensional pore-scale flow cell containing crushed Yucca Mountain tuff, a digital microscope, and theory from Tuller and Or [1999] we have attempted to quantify the saturation and capillary pressure at which water changes from being controlled by van der Waals forces to being held by capillarity, i.e, where films condense and become pendular rings. The tuff is known (from BET analysis) to have a high surface area as well as intra-granular porosity and therefore is likely to absorb relatively thick water films before forming pendular rings. By introducing humid air into a two dimensional cell we observed the growth and distribution of films followed by the formation of pendular rings. Using relative humidity measurements, image analysis, and the Kelvin and Young-Laplace Equations we determined saturation and capillary pressures where the transition from films to pendular rings occurs.
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005