Intermittency between avalanche regimes on grain piles

Area of Science:

• Experimental physics
• Granular material dynamics
• Complex systems

Background:

• Granular avalanches exhibit complex behaviors, often studied in the context of self-organized criticality.
• Understanding intermittency and power-law distributions is crucial for predicting granular flow phenomena.

Purpose of the Study:

• To experimentally investigate discrete grain avalanches driven by a low inflow rate.
• To characterize the different regimes of avalanche behavior and their underlying mechanisms.
• To explore potential applications and theoretical connections to existing models of granular dynamics.

Main Methods:

• Experimental setup involving an erodible pile in a channel with a controlled low inflow rate.
• Observation and analysis of avalanche intermittency, periodicity, and size distributions.
• Development of a toy model to explain power-law size distributions in specific avalanche regimes.

Main Results:

• Observed two distinct avalanche regimes: quasiperiodic and system-spanning, versus irregular with power-law size distribution.
• Demonstrated that the pile's surface state dictates avalanche front propagation.
• Confirmed robustness of observations across different inflow rates and grain types without parameter tuning.

Conclusions:

• The study identifies key factors governing avalanche behavior in granular systems.
• Findings suggest potential applications in pharmaceutical and geophysical granular flows.
• Provides a framework for reconciling self-organized criticality with hysteretic behavior in granular avalanches.