"I'm caught in a dream
Sometimes it ain't what it seems
I'm all in a daze
Can't find my way out of this maze
I'm looking for clues
And wanting a change in the rules..."
From the song "Fractured Love" by Def Leppard
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The applicability of current conceptual models of unsaturated, fracture flow was explored by a comparison of laboratory tests and numerical simulations. An experimental domain of a simplified fracture/matrix system was constructed from twelve limestone bricks stacked four wide and three high, separated by analog “fractures” whose apertures averaged from 1.5 x 10-4 m (vertical fractures) to 1.7 x 10-8 m (horizontal fractures). Water was introduced to the top boundary at a rate of about 1 mL/min to each of the three vertically oriented fractures (for a total of 3 mL/min), and collected by fiberglass wicks at the bottom boundary. These laboratory tests were simulated using four different conceptual models (isotropic and anisotropic equivalent continuum, dual porosity, and discrete fracture models). Despite the simple and well-characterized nature of the experimental system, all of the conceptual models tested failed to reproduce critical aspects of the observed behavior. This comparison implies that important physical processes are lacking from current descriptions of fracture flow in unsaturated media, and casts doubt on the ability of contemporary models to make useful predictions of subsurface flow and transport. |
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The contrast between the behavior predicted by the models below and the experimental results above suggests that some critical physics is missing from current conceptual models of flow in unsaturated, fractured rock. Identifying and including the necessary processes is an active area of research at the University of Idaho, and the Idaho National Engineering and Environmental Laboratory.-Non-uniform wetting of the matrix blocks
-Focusing of flowpaths with increasing vertical distance from the injection points
-Matrix saturation lags fracture wetting front passage by a significant amount of time
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text...
I'm on the lookout for a
sharp graduate student or two, so if the above topics interest you give
me a call (208/885-9259), or E-mail me at jfairley@uidaho.edu.
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Archaeohydrology |