HR: 1330h
AN: H32A-0529    [PDF]
TI: Generating Reproducible Heterogeneity for Laboratory Flow and Transport Experiments
AU: * Griffith, B C
EM: cgrffith@bellsouth.net
AF: The University of Mississippi, Dept. of Geology and Geological Engineering 118 Carrier Hall, University, MS 38677 United States
AU: Holt, R M
EM: rmholt@olemiss.edu
AF: The University of Mississippi, Dept. of Geology and Geological Engineering 118 Carrier Hall, University, MS 38677 United States
AU: Glass, R J
EM: rjglass@sandia.gov
AF: Flow Visualization and Processes Laboratory, Sandia National Laboratories, Albuquerque, NM 87185-0735 United States
AB: To understand the impact of heterogeneity on unsaturated flow and transport processes, many researchers have begun to conduct flow and transport experiments in laboratory analogues to heterogeneous geologic materials. Most of these experiments are conducted in macroheterogeneous media where homogeneous units are arranged to represent large-scale heterogeneity. However, most sedimentary media displays heterogeneity at a hierarchy of scales, the smallest of which is a stratum that is graded. Such stratification can lead to complicated wetted-phase structures that influence moisture retention, unsaturated hydraulic conductivity, access to surface area for reaction, and non-ideal transport. Because of the difficulty in reproducing "geologically realistic" microheterogeneity, the impact of small-scale stratification on flow and transport is difficult to evaluate using current laboratory constructed analogues. We have developed and evaluated a new approach for constructing reproducible, "geologically realistic" heterogeneity for laboratory flow and transport experiments. Using an apparatus with a computer-controlled arm, mixtures of sand are deposited in an experimental chamber through a tube. Mechanical grading processes within the tube and the chamber lead to stratification that mimics that produced by sedimentary processes. By varying the arm speed, stratum thickness and angle can be controlled. By using different sand mixtures, the grain size at the top and bottom of a stratum can be varied. Through the use of carefully designed computer programs, a variety of reproducible micro/macroheterogeneous structures can be produced.
DE: 1832 Groundwater transport
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2003 Fall Meeting