Ergodicity breaking dynamics of arch collapse

Abstract

Gravity driven flows such as in hoppers and silos are susceptible to clogging due to the formation of arches at the exit whose failure is the key to re-initiation of flow. In vibrated hoppers, clog durations exhibit a broad distribution, which poses a challenge for devising efficient unclogging protocols. Using numerical simulations, we demonstrate that the dynamics of arch shapes preceding failure can be modeled as a continuous time random walk (CTRW) with a broad distribution of waiting times, which breaks ergodicity. Treating arch failure as a first passage process of this random walk, we argue that the distribution of unclogging times is determined by this waiting time distribution. We hypothesize that this is a generic feature of unclogging, and that specific characteristics, such as hopper geometry, and mechanical properties of the grains modify the waiting time distribution.

5 pages, 5 figures, +Supplementary Information

References in corpus (5)

• Random Time-Scale Invariant Diffusion and Transport Coefficients
• Fraction of clogging configurations sampled by granular hopper flow
• Role of vibrations in the jamming and unjamming of grains discharging from a silo
• Invited review: Clogging of granular materials in bottlenecks
• Ergodic properties of continuous-time random walks: finite-size effects and ensemble dependences

Cited by in corpus (5)

• A Trap Model for Clogging and Unclogging in Granular Hopper Flows
• Granular flow from silos with rotating orifice
• Discharge of elongated grains in silos under rotational shear
• Pressure dynamics in the bottleneck flow of self-propelled particles
• Particle flow rate in silos under rotational shear