title: Gas-induced fluidization of mobile liquid-saturated grains.
abstract: Gas invasion in liquid-saturated sands exhibits different morphologies and dynamics. For mobile beds, the repeated rise of gas through the layer leads to the growth of a fluidized zone, which reaches a stationary shape. Here, we present experimental results characterizing the evolution of the fluidized region as a function of the gas-flow rate and grain size. We introduce a new observable, the flow density, which quantifies the motion of the grains in the system. The growth of the fluidized zone is characterized by a spatiotemporal analysis, which provides the stabilization time, τ(s). In the stationary regime, we report two main contributions to motion in the fluidized region: the central gas rise and a convective granular motion. Interestingly, a static model with a fixed porous network accounts for the final shape of the invasion zone. We propose an explanation where the initial gas invasion weakens the system and fixes since the early stage the morphology of the fluidized zone.
authors.affiliation: Instituto de Fisica, Pontificia Universidad Católica de Valparaiso, Av. Universidad 330, Valparaiso, Chile.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Ramos
authors.affiliation: Instituto de Fisica, Pontificia Universidad Católica de Valparaiso, Av. Universidad 330, Valparaiso, Chile.
authors.forename: Germán
authors.initials: G
authors.lastname: Varas
authors.affiliation: Laboratoire de Physique, École Normale Supérieure de Lyon, Université de Lyon, CNRS UMR5672, 46 Allée d'Italie, 69364 Lyon Cedex 7, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Géminard
authors.affiliation: Laboratoire de Physique, École Normale Supérieure de Lyon, Université de Lyon, CNRS UMR5672, 46 Allée d'Italie, 69364 Lyon Cedex 7, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Vidal