Kinetic roughening and pinning of coupled precursor and impregnation fronts in porous media

In the paper wetting experiments at low evaporation rate, after a short Washburn regime the film flow of filtered water overtakes the main impregnation front. Accordingly, we study the kinetic roughening dynamics and pinning of two strongly coupled fronts moving in different papers. We find that the kinetic roughening dynamics of precursor and main fronts belongs to different universality classes, nevertheless, at the final stage the distance between the fronts decrease until both fronts are pinned in the same configuration zP(x,y), the scaling properties of which are determined by the long-range correlations in the pore network