HR: 11:20h
AN: H42C-05    [Abstracts]
TI: Verification of Chaotic Advection Enhanced Mixing in Porous Media Using Real Time Imaging
AU: * Dathe, A
EM: adathe@sci.ccny.cuny.edu
AF: City College of New York, Department of Earth and Atmospheric Sciences, Convent Ave at 138th Street, 106 Marshak, New York, NY 10031, United States
AU: Zhang, P
EM: pzhang@sci.ccny.cuny.edu
AF: City College of New York, Department of Earth and Atmospheric Sciences, Convent Ave at 138th Street, 106 Marshak, New York, NY 10031, United States
AU: Bagtzoglou, A C
EM: acb@engr.uconn.edu
AF: University of Connecticut, Civil and Environmental Engineering, 261 Glenbrook Road, Storrs, CT 06269, United States
AB: Chaotic advection refers to the highly complicated particle trajectories observed in the Lagrangian frame of reference under simple well-behaved velocity fields. Recent theoretical work indicates that time-periodic oscillations in low Reynolds (laminar) regimes can cause laminar flows to exhibit very complicated particle trajectories and cause substantial mixing in porous media. If proved successful, the chaotic advection methodology would allow the processes of bioremediation to occur much faster by enhancing the mixing of nutrients and microorganisms. This work intends to verify the theoretical work using a newly developed light reflection imaging system that is capable of real time quantitative monitoring of low concentrations of fluorescent dye and colloids. A fluorescent dye is injected into a decimeter-scale flow chamber filled with clean quartz sand via a well-triplet located at the center of the chamber. Dye distributions within the flow chamber are imaged over time and converted to absolute concentrations based on calibration curves. Two flow schemes are used, a time- dependent oscillatory flow scheme and a constant flow scheme (control). To establish the oscillatory flow, one of the three wells is randomly assigned a pumping magnitude with realistic constrains and a direction (injection or withdrawal), and the magnitude is then randomly partitioned to the other wells, which are assigned the opposite flow direction of the first well. For the control experiment, one well is constantly injecting while the other two are both withdrawing at half the rate of the first well. Our results show that the dye plume produced by the oscillating flow is more contained than the dye plume from the control experiment, and the dye concentration is higher in the more contained plume. Dye concentrations at certain points around the wells show higher fluctuations over time for the chaotic advection experiment than those for the control experiment. Explanations on how the chaotic flow can better contain a plume while simultaneously increasing mixing within the plume will be discussed.
DE: 1828 Groundwater hydraulics
DE: 1832 Groundwater transport
DE: 4499 General or miscellaneous
SC: Hydrology [H]
MN: 2007 Fall Meeting