Flow enhancement of a rough fracture

We study experimentally and numerically the permeability of a rough fractur e at laboratory scale when viscous forces are dominating (low Reynolds numb er). The experimental setup includes a granite fracture surface (10 x 10 cm (2)) opened in mode I. It allows a continuous opening of the fracture paral lel to its mean plane. The fracture roughness is measured and characterized in terms of self-affine heterogeneities. Its isotropy is checked. The depa rture 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 orient ation by rotating the fracture by 90 degrees. A strongly anisotropic hydrau lic behavior is observed and results from the geometrical heterogeneities t hat exist up to the fracture macro-scale.