Influence of centrifugal forces on phase structure in partially saturated media

Abstract

[1] Centrifugal methods are gaining increased attention for use in hydrologic experiments within partially saturated media. Through use of a Modified Invasion Percolation (MIP) model, we examine the influence of a stabilizing centrifugal (buoyancy) force on the invasion of a light nonwetting fluid (e.g., air) into a heterogeneous porous media initially saturated with a denser, wetting fluid (e.g., water). Results show that while capillary heterogeneity controls phase structure outside of a centrifugal field, the influence of capillary heterogeneity varies with angular velocity in a centrifugal field. As the angular velocity is increased, the invasion processes and phase structure become increasingly insensitive to heterogeneity, regardless of its style or orientation. Because phase structure critically influences flow processes and petrophysical properties (pressuresaturation, relative permeability, electrical resistivity, etc.), the design of centrifugal experiments must carefully consider this interplay between capillary heterogeneity and centrifugal force.

Effect of Topographic Characteristics on Compound Topographic Index for Identification of Gully Channel Initiation Locations

“…The effect of terrain characteristics and DEM resolution on CTI values and distribution was investigated through the use of probabilistic random functions (Holt et al, 2003). Two-dimensional regularly spaced grids (1024 rows × 1024 columns) were populated with simulated elevation residual values (deviations from local mean elevation) randomly generated using spectral and fast Fourier transform (FFT) methods ( fig.…”

Development of slender transport pathways in unsaturated fractured rock: Simulation with modified invasion percolation

“…Invasion Percolation (IP) is a simple growth algorithm that generates phase structure through the operation of local rules that embody the physics of immiscible displacement within a network of pores. First introduced by Wilkinson and Willemsen [1983], IP has been modified (MIP) in many ways such as to bring in gravity [ Meakin et al , 1992; Glass and Yarrington , 1996; Ioannidis et al , 1996], centrifugal forces [ Holt et al , 2003], viscous forces [ Xu et al , 1998], as well as capillary smoothing mechanisms in porous media [ Blunt and Scher , 1995; Glass and Yarrington , 1996] and fractures [ Glass et al , 1998]. Recently, MIP has been applied to the movement of DNAPL within a fracture network under conditions of ambient groundwater flow [ Ji et al , 2003] and further modified to simulate pulsation or dripping as occurs in many buoyant‐gravity destabilized flows [ Glass and Yarrington , 2003].…”

From invasion percolation to flow in rock fracture networks

“…In this work, physical modifications to the model are proposed to study the gas-water displacement process in the DFNs. IP has been modified (MIP) in many ways in the past to incorporate more geometrical and physical details of the network like force fields such as gravity [12][13][14][15], centrifugal forces [16], viscous forces [17], as well as capillary smoothing mechanisms in porous media [13,18] and inside single fractures [19]. In this work, we have modified the IP model to a more realistic description of the invading progress.…”