Whether it be in a pipe or a silo, clogging is generally unpleasant and may border on the nightmare in the worst cases. This phenomenon is due to the formation of stable arches or vaults that span a constriction and prevent further flow. A natural solution to alleviate it is to shake the setup. Indeed, gentle vertical vibrations were known to be able to induce an unclogging transition, whereby clogs are destroyed by the shaking, although this may take anomalously long times.
The possibility of such an unclogging transition under vertical vibrations is questioned in our recent paper, published in Physical Review Letters with colleagues from the eminent Granular Lab at the University of Navarra (Spain). In this work, stable arches or vaults are likened to energy wells that trap the system, and a simple trap model inspired from the physics of glasses is put forward to describe both the statistics of unclogging under vibrations and some features of clogging under no vibrations. Thus, it is suggested that these two phenomena (clogging and unclogging), which were thought to be of distinct natures, may have a common physical underpinning.
