Turbulent-like dynamics of slow imbibition fronts
5 February 2016
French National Centre for Scientific Research
Laboratoire de Physique, ENS-Lyon, France
I will present an experimental study of the dynamics of a viscous fluid interface forced to invade a disordered medium at constant flow rate.
A multi-scale analysis of the spatially averaged velocity Vl (t) of those imbibition fronts measured at scale l reveals that the slow front dynamics is intermittent: the distributions of the velocity increments ΔVl (τ) = Vl (t+ τ) - Vl (t) evolve continuously through time scales τ, from heavy-tailed to Gaussian—reached at a time lag τC, set by the extent of the medium heterogeneities. Intermittency results from capillary bursts triggered from the smallest scale of the disorder up to the scale lC at which viscous dissipation becomes dominant. The effective number of degrees of freedom of the front l = lC controls its intensity.