title: Pinning and avalanches in hydrophobic microchannels.
abstract: Rare events appear in a wide variety of phenomena such as rainfall, floods, earthquakes, and risk. We demonstrate that the stochastic behavior induced by the natural roughening present in standard microchannels is so important that the dynamics for the advancement of a water front displacing air has plenty of rare events. We observe that for low pressure differences the hydrophobic interactions of the water front with the walls of the microchannel put the front close to the pinning point. This causes a burstlike dynamics, characterized by series of pinning and avalanches, that leads to an extreme-value Gumbel distribution for the velocity fluctuations and a nonclassical time exponent for the advancement of the mean front position as low as 0.38.
authors.affiliation: Departament ECM, Facultat de Física, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Queralt-Martín
authors.forename: M
authors.initials: M
authors.lastname: Pradas
authors.forename: R
authors.initials: R
authors.lastname: Rodríguez-Trujillo
authors.forename: M
authors.initials: M
authors.lastname: Arundell
authors.forename: E
authors.initials: E
authors.lastname: Corvera Poiré
authors.forename: A
authors.initials: A
authors.lastname: Hernández-Machado