Ramos Gabriel, Varas Germán, Géminard Jean-Christophe, Vidal Valérie
Instituto de Fisica, Pontificia Universidad Católica de Valparaiso, Av. Universidad 330, Valparaiso, Chile.
Laboratoire de Physique, École Normale Supérieure de Lyon, Université de Lyon, CNRS UMR5672, 46 Allée d'Italie, 69364 Lyon Cedex 7, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Dec;92(6):062210. doi: 10.1103/PhysRevE.92.062210. Epub 2015 Dec 30.
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.
液体饱和砂中的气体侵入呈现出不同的形态和动力学。对于移动床，气体反复穿过砂层上升会导致流化区域的生长，该区域会达到一个稳定的形状。在此，我们展示了实验结果，这些结果表征了流化区域随气体流速和颗粒尺寸的演变。我们引入了一个新的可观测参数——流动密度，它量化了系统中颗粒的运动。流化区域的生长通过时空分析来表征，时空分析给出了稳定时间τ(s)。在稳定状态下，我们报告了流化区域运动的两个主要因素：中心气体上升和对流颗粒运动。有趣的是，一个具有固定多孔网络的静态模型能够解释侵入区域的最终形状。我们提出一种解释，即初始气体侵入会削弱系统，并从早期就固定流化区域的形态。
