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Segregation patterns in rotating cylinders determined by the size difference, density ratio, and cylinder diameter.
Kurumi Kondo1, Hiroyuki Ebata1, Shio Inagaki2
1Department of Physics, Kyushu University, Fukuoka, 819-0395, Japan.
Scientific Reports
|August 18, 2023
Summary
Granular materials in rotating cylinders segregate into bands, contrary to mixing expectations. New research identifies key parameters controlling this segregation, enabling prediction and scaling of band width.
Area of Science:
- Physics of granular materials
- Fluid dynamics and complex systems
Background:
- Granular materials often segregate under mechanical agitation, contrary to expected mixing.
- Bidisperse mixtures in rotating cylinders form alternating bands, with dynamic angle of repose previously thought to be the dominant factor.
Purpose of the Study:
- To clarify experimental conditions governing granular material segregation in rotating cylinders.
- To identify key dimensionless parameters influencing the segregated state.
Main Methods:
- Conducted an exhaustive parameter search using three dimensionless parameters: particle size difference, specific density ratio, and cylinder diameter to particle size ratio.
- Performed additional experiments to investigate the effect of cylinder rotational speed.
Main Results:
- Successfully predicted the segregated state of granular materials based on the identified parameters.
- Discovered that band width can be effectively scaled by combining the three key parameters.
Conclusions:
- The dynamic angle of repose is not always the sole determinant of granular segregation.
- A systematic approach using dimensionless parameters allows for prediction and scaling of segregation patterns in granular mixtures.
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