Geometrical properties of fractured basalt and sandstone surfaces are studied by measuring the length distribution of shadows appearing under grazing illumination. For self-affine surfaces, the distribution is predicted to follow a power law of the shadow length with an exponent depending only...

Gravity driven instabilities in model porous packings of 1mm diameter spheres are studied by comparing the broadening of the displacement front between fluids of slightly different densities in stable and unstable configurations. Water, water–glycerol and water–polymer solutions are used to...