Triggering avalanches by transverse perturbations in a rotating drum

Area of Science:

• Physics
• Complex Systems
• Nonlinear Dynamics

Background:

• Avalanches in granular materials are often studied in rotating drum systems.
• The stick-slip regime in such systems is characterized by intermittent motion.
• Understanding the triggers for avalanche onset is crucial for granular flow dynamics.

Purpose of the Study:

• To investigate the role of small-scale perturbations in initiating avalanches.
• To identify the appropriate order parameter for describing the system's behavior.
• To determine the governing parameter for avalanche onset under specific conditions.

Main Methods:

• Utilizing a rotating drum system operating in the stick-slip regime.
• Applying small-amplitude vibrations along the axis of rotation.
• Analyzing the system's dynamics using kinetic energy as the order parameter.
• Developing a theoretical model based on supercritical Hopf bifurcation.

Main Results:

• Kinetic energy is identified as the order parameter describing the system.
• Avalanche onset is governed by oscillation amplitude at high frequencies, challenging previous findings.
• A theoretical model successfully explains the transition between continuous and discrete avalanche regimes.

Conclusions:

• Small-scale vibrations, specifically oscillation amplitude at high frequencies, are critical for triggering avalanches.
• The system's behavior transitions between continuous and discrete regimes via a supercritical Hopf bifurcation.
• This research provides new insights into granular flow control and predictability.