Hysteretic transition between avalanches and continuous flow in rotated granular systems

Area of Science:

• Physics of granular materials
• Nonlinear dynamics
• Statistical physics

Background:

• Rotating granular systems exhibit a hysteretic transition between discrete avalanches and continuous flow when rotation rates change adiabatically.
• This phenomenon has been observed in experimental setups like rotating drums or cylinders.

Purpose of the Study:

• To explain the observed hysteresis in granular flow using a minimal model.
• To investigate the role of global fluctuations in this hysteretic behavior.
• To reconcile experimental findings with molecular dynamics simulations.

Main Methods:

• Utilizing a recently proposed minimal model for surface flow along granular piles.
• Incorporating global Langevin-type fluctuations into the model.
• Analyzing the impact of varying fluctuation magnitudes on the system's behavior.

Main Results:

• The hysteresis in the transition from discrete avalanches to continuous flow is explained by global Langevin-type fluctuations.
• For large fluctuation magnitudes, corresponding to nearly elastic grains, the hysteresis vanishes.
• The presence of hysteresis is dependent on the magnitude of these fluctuations.

Conclusions:

• Global Langevin fluctuations are key to understanding the hysteretic transition in rotating granular systems.
• The vanishing of hysteresis at high fluctuation levels may explain why molecular dynamics simulations have not detected it.
• The minimal model provides a framework for further investigation into granular flow dynamics.