LOW RAYLEIGH NUMBER CONJUGATE CONVECTION IN STRAIGHT INCLINED FRACTURES IN ROCK

Abstract

This investigation explores the natural convection in a water-filled straight inclined fracture in rock subject to a uniform background temperature increasing with depth. The numerical solutions cover aspect ratios from 2 to 50, with Rayleigh numbers of magnitude 1, 10, and 100. The inclination angle ranges from 0° to 90° to the horizontal. The results demonstrate that a straight inclined fracture experiences a gradient-driven convection flow whose strength is strongly dependent on aspect ratio. The flow increases as the fracture angle changes from either purely horizontal or purely vertical, with a maximum at 45°. It is observed that fractures with an aspect ratio as low as 10 exhibit average velocities at the midplane of nearly 90% of the values calculated from the analytical solution for the infinite aspect ratio limit.

Additional information

Notes on contributors

Edward J. Shaughnessy

The authors gratefully acknowledge the support of this research provided by the North Carolina Supercomputer Center through the award of computer time on the Center's Cray Y-MP.