Gravity-driven fingering in unsaturated fractures
Gravity-driven wetting-front instability is known to occur in both porous media and Hele-Shaw cells. A systematic investigative procedure for studying gravity-driven fingering in unsaturated, rough-walled fractures is described. As a first step toward understanding this system, experiments were performed in an analogue fracture consisting of two roughened glass plates held in close contact. Results from preliminary experiments in both initially dry and wet analogue fractures are presented, including measurements taken from individual fingers within a fully unstable flow field. For initially dry fractures, increasing the volume of fluid contained in the front leads to increases in both finger width and velocity. Finger velocity also was observed to increase with gravitational gradient. Once a finger structure develops in an initially dry fracture, the structure persists in subsequent infiltration events. In uniformly wet fractures, fingers are found to be more numerous and thinner and to have higher velocity than fingers formed in initially dry fractures.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10116073
- Report Number(s):
- SAND--91-1985C; CONF-920430--45; ON: DE92006799
- Country of Publication:
- United States
- Language:
- English
Similar Records
Small-scale behavior of single gravity-driven fingers in an initially dry fracture
Modeling gravity-driven fingering in rough-walled fractures using modified percolation theory