Numerical investigation on the clogging-collapsing events in granular discharge

Granular flow in hoppers is widely encountered in industries and daily life. Despite its ubiquity, understanding on its basic flow behavior is still limited. Typically, the flow may be interrupted by the formation of arches and the phase transition ensues, and in general these arches may not collapse without external energy input such as vibration. However, in this study, the rare events of granular flow arrested by the formation of unstable arches and then restarted by their spontaneous collapsing, or the clogging-collapsing events, were observed in both lab experiments and numerical simulations in the discrete element method (DEM). It was demonstrated that the clogging may result from the coordinated evolution of the entire force chain system and the kinetic energy dissipated incompletely in bulk is mainly responsible for the collapsing. The evolution of the kinetic energy displays different modes in the clogging-collapsing , permanent clogging events, suggesting that the collapsing can be predicted by monitoring the variance of the kinetic energy.

Automated summary

This study observed rare events of granular flow being arrested by the formation of unstable arches and then restarted by their spontaneous collapsing, known as clogging-collapsing events. The research demonstrated that the coordinated evolution of the entire force chain system and the incomplete dissipation of kinetic energy are the main factors responsible for the collapsing.