HR: 10:50h
AN: H42A-03    [Abstracts]
TI: Multiphase Flow in Micro-fracture Junctions
AU: * Basagaoglu, H
EM: basagaoh@geo.oregonstate.edu
AF: Department of Geosciences, 202B Wilkinson Hall Oregon State University, Corvallis, OR 97331 United States
AU: Meakin, P
EM: meakp@inel.gov
AF: Idaho National Laboratory, P.O. Box 1625, MS 2025 , Idaho Falls, ID 83415 United States
AU: Succi, S
EM: succi@iac.rm.cnr.it
AF: Instituto Applicazioni Calcolo, CNR-IAC Viale del Poloclinico 137, Rome, 00161 Italy
AU: Wildenschild, D
EM: wildend@geo.oregonstate.edu
AF: Dept. of Geosciences / Dept. of Civil, Construction, and Environmental Engineering , 255 Wilkinson Hall Oregon State University, Corvallis, OR 97331 United States
AB: A two-dimensional two-phase lattice-Boltzmann model was used to simulate immiscible fluid flow in four micro-fracture geometries closely related to geological fractured systems: (1) a fracture junction with fractal surfaces embedded in a non-porous matrix; (2) a fracture junction embedded in a heterogeneous porous matrix; (3) a heterogeneous porous medium overlying a fracture with fractal surfaces; and (4) a fracture network with fractal surfaces enclosed by a non-porous medium. The spatio-temporal distributions of fluids in fracture junctions were controlled by interplays between velocity-dependent contact angle dynamics, mediated by surface roughness, and pore-scale gravitational, viscous, and capillary forces. All simulations were conducted with actual physical units. Sensitivities of lateral and vertical spreads of fluids in the fracture junctions to the orientation of fracture junctions (tilted vs. vertical) and the wetting strength of fluids were analyzed via temporal moment analyses for the first two geometries. The simulation results revealed that the receding and advancing contact angles varied strongly with the transient fluid velocity. The patterns and distributions of thin films (continuous vs. discontinuous) on rough fracture walls were largely controlled by the wetting strength of the fluids. The spatio-temporal distributions of fluids were highly sensitive to the domain size and boundary conditions (periodic, no-flow, constant density, and flux-type). Single- and two-sided wetting of fracture aperture walls and long-term entrapment of a nonwetting less-dense fluid by a wetting dense fluid were observed in the simulations. These numerical results are useful for the design of experiments and for analyzing the relative strengths of pore-scale processes in more complex and realistic fracture systems such as those encountered at the Yucca Mountain and Idaho National Laboratory sites.
DE: 1832 Groundwater transport
DE: 1847 Modeling
SC: Hydrology [H]
MN: Fall Meeting 2005