Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02454, USA.
TIFR International Center for Theoretical Sciences, Shivakote, Bengaluru 560089, India.
Phys Rev E. 2018 Apr;97(4-1):040901. doi: 10.1103/PhysRevE.97.040901.
Flows in hoppers and silos are susceptible to clogging due to the formation of arches at the exit. The failure of these arches is the key to reinitiation of flow, yet the physical mechanism of failure is not well understood. Experiments on vibrated hoppers exhibit a broad distribution of the duration of clogs. Using numerical simulations of a hopper in two dimensions, we show that arches become trapped in locally stable shapes that are explored dynamically under vibrations. The shape dynamics, preceding failure, break ergodicity and can be modeled as a continuous-time random walk with a broad distribution of waiting, or trapping, times. We argue that arch failure occurs as a result of this random walk crossing a stability boundary, which is a first-passage process that naturally gives rise to a broad distribution of unclogging times.
料斗和料仓中的物料流动容易因出口处形成拱形而堵塞。这些拱形结构的破坏是重新开始流动的关键，但破坏的物理机制尚不清楚。对振动料斗的实验表明，堵塞的持续时间分布广泛。我们通过对二维料斗的数值模拟表明，拱形结构被困在局部稳定的形状中，这些形状在振动下会动态地被探索。在破坏之前，形状动力学会打破遍历性，并且可以建模为具有广泛等待时间或捕获时间分布的连续时间随机游走。我们认为，拱形结构的破坏是由于这种随机游走越过了稳定性边界，这是一个自然导致解堵时间分布广泛的首次通过过程。
