Flow regimes and repose angle in a rotating drum filled with highly concave particles

Area of Science:

• Granular physics
• Complex systems
• Material science

Background:

• Understanding granular material flow is crucial in various industrial processes.
• Particle shape and interactions significantly influence bulk behavior.
• Limited research exists on highly concave particle packings in dynamic systems.

Purpose of the Study:

• To investigate the flow regimes and repose angles of highly concave particle packings in a rotating drum.
• To determine how particle geometry, friction, and rotation speed affect granular flow dynamics.
• To establish phase diagrams for different flow behaviors.

Main Methods:

• Experimental setup involving a rotating drum with controlled particle shapes and properties.
• Systematic variation of grain geometry (spherical to nonconvex), frictional properties, and particle branch number.
• Analysis of flow regimes (rolling and slumping) using quantitative criteria like repose angle difference and area ratio.

Main Results:

• Identification of two distinct flow regimes: rolling (solid-like near walls, liquid-like at free surface) and slumping (cyclic avalanches, solid body rotation).
• Demonstration that particle concavity, friction, and drum speed are key factors influencing flow behavior.
• Construction of phase diagrams illustrating the transitions between identified flow regimes.

Conclusions:

• Particle concavity and friction play a critical role in dictating granular flow patterns.
• The study provides new insights into the mechanical behavior of metagranular matter.
• Findings contribute to a better understanding of granular material dynamics in complex geometries.