Experimental Evidence of Disorder Effects in Hydrodynamic Dispersion

Abstract

Thanks to an acoustic technique, we have measured the longitudinal dispersion of miscible fluids in three disordered porous media over a wide range of Péclet number. The hydrodynamic dispersion is always Gaussian whatever the flow rate, the sample, or the length of the sample is. The low-flow-rate regime gives the tortuosity of the medium. At higher flow rate, two media having the same permeability and tortuosity but very different pore-size distributions exhibit linear (glass beads) and nonlinear dispersion (foamlike fireproof brick) in accordance with recent numerical simulations.