title: Avalanches and non-Gaussian fluctuations of the global velocity of imbibition fronts.
abstract: We present an experimental study of the global velocity V(t) of a viscous fluid interface during forced-flow imbibition in a disordered medium. Our high resolution setup shows that the fronts display an intermittent behavior signature of a burstlike dynamics, with power-law distributed avalanches. When measured at scales comparable to the correlation length, velocity fluctuations follow an asymmetric non-Gaussian distribution, whose skewness increases with decreasing measuring window and/or injection flow rate, offering the effective number of degrees of freedom probed in our experiment.
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Planet
authors.forename: Stéphane
authors.initials: S
authors.lastname: Santucci
authors.forename: Jordi
authors.initials: J
authors.lastname: Ortín