Conserved dynamics and interface roughening in spontaneous imbibition: A critical overview

Imbibition phenomena have been widely used experimentally and theoretically to study the kinetic roughening of interfaces. We critically discuss the e xisting experiments and some associated theoretical approaches on the scali ng properties of the imbibition front, with particular attention to the con servation law associated to the fluid, to problems arising from the actual structure of the embedding medium, and to external influences such as evapo ration and gravity. Our main conclusion is that the scaling of moving inter faces includes many crossover phenomena, with competition between the avera ge capillary pressure gradient and its fluctuations setting the maximal len gthscale for roughening. We discuss the physics of both pinned and moving i nterfaces and the ability of the existing models to account for their prope rties.