Flow enhancement of a rough fracture

We study experimentally and numerically the permeability of a rough fracture at laboratory scale when viscous forces are dominating (low Reynolds number). The experimental setup includes a granite fracture surface (10 × 10 cm²) opened in mode I. It allows a continuous opening of the fracture parallel to its mean plane. The fracture roughness is measured and characterized in terms of self‐affine heterogeneities. Its isotropy is checked. The departure from the cubic law is measured as a function of the aperture opening (for mean separations between 4.0 and 10.3 mm) and the pressure drop orientation by rotating the fracture by 90 degrees. A strongly anisotropic hydraulic behavior is observed and results from the geometrical heterogeneities that exist up to the fracture macro‐scale.