Application of 2-D random generators to the study of solute transport in fractures

Two fields with random aperture distribution and different spatial structures are taken as models to study solute transport in fractures. One network has non-vaunishing long range correlations and represents a fractal pattern. The other one has a finite correlation length and an exponential covariance function. Based on these fields, two physical fracture models were produced and used to record the movement of a coloured solute by means of a CCD camera. The pictures obtained were analyzed with image processing methods. A front tracking algorithm shows that the growth law of the frontal variance is a power law of time with the exponent depending on the Hut-st coefficient of the aperture distribution in the case of the fractal pattern, while it is a linear function of time for the case of the finite correlation length.