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Updated: Mar 3, 2026
11:51
Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions
Published on: February 22, 2018
9.2K
Gravity-Driven Flux of Particles through Apertures.
Ram Sudhir Sharma1, Alexandre Leonelli1, Kevin Zhao2
1University of California, Department of Mechanical Engineering, Santa Barbara, California 93106, USA.
Physical Review Letters
|March 1, 2026
Summary
Granular material discharge is explained by a new kinematic framework. This model separates velocity and packing effects, revealing a universal correction factor for flow deviations.
Area of Science:
- Granular physics
- Fluid dynamics
- Materials science
Background:
- Gravity-driven granular discharge is a fundamental problem.
- Classical descriptions rely on empirical laws with fitting parameters.
- Disentangling mass flux into velocity and packing is crucial.
Purpose of the Study:
- To develop a kinematic framework for granular discharge.
- To understand deviations from free-fall limits.
- To explain the universality of granular flow.
Main Methods:
- Combining three-dimensional experiments and simulations.
- Defining a dimensionless flux ratio.
- Analyzing spherical cohesionless grains.
Main Results:
- A dimensionless flux ratio captures confinement effects.
- Deviations from free-fall are described by an exponential correction factor.
- A characteristic length scale of 10-15 grain diameters modifies packing structure.
Conclusions:
- The proposed kinematic framework explains granular discharge universality.
- The framework moves beyond purely empirical descriptions.
- Understanding packing structure modification is key to flow behavior.
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