Water flow and slip on NAPL-wetted surfaces of a parallel-walled fracture

摘要

The effects of various wetting conditions and aperture sizes on water flow and slip in a parallel-walled fracture were investigated. Water flow experiments showed that a larger slip occurred as the surface became more hydrophobic. For a creosote-wetted surface of the fracture with an aperture of 508 mm, the increase in the water flow rate due to the slip was as much as 10.0% compared to that in a water-wetted surface. Similarly to a water-wetted surface, no slip took place at a gasoline-wetted surface, which was weakly hydrophobic. The slip lengths, a notional distance from the wall to a point inside the wall where fluid velocity extrapolates to zero, for light oil- and creosote-wetted surfaces were constant over a range of flow velocities in the laminar flow regime. The study indicates that no slip boundary condition-based equations are not adequate for quantifying water flow through NAPL-wetted fractures.