Flow rule of dense granular flows down a rough incline

Area of Science:

• Physics
• Geophysics
• Materials Science

Background:

• Granular flows on inclined planes are common in nature and industry.
• Understanding their flow behavior is crucial for predicting phenomena like landslides and designing material transport systems.

Purpose of the Study:

• To experimentally investigate and refine the flow rules for granular materials on rough inclined planes.
• To evaluate existing and propose new scaling laws for granular flow dynamics.

Main Methods:

• Experiments were conducted using sand, glass beads, and copper particles of varying sizes and shapes on inclined planes.
• Measurements included flow thickness (h) at which flow subsides (hs) as a function of plane inclination (theta) and surface velocity (u) as a function of flow thickness (h).

Main Results:

• The Pouliquen flow rule provided reasonable but imperfect collapse of velocity-thickness data for sand and glass beads.
• An improved scaling law, incorporating the divergence angle (theta1) of hs(theta) curves, yielded better data collapse for sand and glass beads.
• A systematic increase in the flow parameter (beta) was observed with increasing theta1 for sand and glass beads.
• Copper particles with different shapes did not conform well to the tested flow rules.

Conclusions:

• The proposed scaling law offers a more accurate description of granular flow dynamics for spherical particles like sand and glass beads.
• Particle shape significantly influences flow behavior, indicating limitations of current models for non-spherical granular materials.
• Further research is needed to develop flow rules applicable to a wider range of granular material shapes.