HR: 1340h
AN: H33A-1362    [Abstracts]
TI: On the Determination of Transverse Dispersivity: Experiments and Simulations in a Helix and a Cochlea
AU: * Benekos, I
EM: ybenekos@stanford.edu
AF: Stanford University, 380 Panama Mall, Terman Engineering Center, room M13, Stanford, CA 94305 United States
AU: Kitanidis, P
EM: peterk@stanford.edu
AF: Stanford University, 380 Panama Mall, Terman Engineering Center, room M13, Stanford, CA 94305 United States
AB: Transverse dispersion in porous media has been identified as a key parameter in a variety of subsurface processes. It controls the dissolution rate of contaminant sources, the dilution of conservative solutes, the mixing of reacting solutes, and plays a decisive role in the decay of concentration fluctuations. Estimating the transverse dispersivity, a property of the porous medium, is necessary for assessing the hydrodynamic part of the transverse dispersion. This work presents a methodology and tracer experiments to measure the transverse dispersivity of homogeneous isotropic media using a cochlea, a spiral shaped cavity looking like a nautilus shell, and a helix. The incentive is that the transport of a conservative tracer in a device with spiral flow motion results in a concentration breakthrough curve that is inversely related to the transverse dispersion parameters. The smaller the transverse dispersivity is the larger is the spread of the breakthrough curves and vice versa. By performing conservative tracer experiments in a helix and a cochlea we can obtain experimental breakthrough curves. The flow field in the helix is complex and it is solved numerically. In the cochlea the flow field is simpler and is solved analytically. The solution of the flow field is applied to particle-tracking random-walk simulations of solute transport which is used as forward model in a non-linear optimization method to determine the transverse dispersivity of the device filling. Estimates of the transverse dispersivity are obtained for each experiment. The relative advantages of each device are discussed.
DE: 1832 Groundwater transport
DE: 1839 Hydrologic scaling
DE: 1847 Modeling
DE: 1894 Instruments and techniques: modeling
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: Fall Meeting 2005