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Shape matters: Competing mechanisms of particle shape segregation
D Hernández-Delfin1,2, D R Tunuguntla3, T Weinhart3
1Departamento de Física y Matemática Aplicada, Universidad de Navarra, P.O. Box. 177, E-31080 Navarra, Spain.
Physical Review. E
|December 23, 2022
Summary
Granular segregation in sheared mixtures is driven by two distinct mechanisms: kinetic and gravity. Particle shape (aspect ratio) influences their competition, leading to non-monotonic segregation intensity and reversals.
Area of Science:
- Physics
- Materials Science
- Engineering
Background:
- Granular mixtures segregate when sheared, a phenomenon attributed to multiple mechanisms.
- Previous research has proposed two primary segregation mechanisms, but their coexistence and relative importance remain debated.
Purpose of the Study:
- To investigate the existence and interplay of two distinct segregation mechanisms in bidisperse granular mixtures.
- To elucidate the role of particle shape (aspect ratio) in driving segregation phenomena.
Main Methods:
- Simulations of bidisperse mixtures of spheroids with equal volume in a rotating drum.
- Analysis of segregation driven by relative overstress, considering both kinetic and gravity mechanisms.
Main Results:
- Evidence supports two distinct segregation mechanisms driven by relative overstress.
- Particle aspect ratio (AR) significantly impacts segregation, causing non-monotonic intensity and direction reversals.
- The kinetic mechanism dominates for near-spherical particles, while the gravity mechanism becomes crucial for extreme aspect ratios.
Conclusions:
- Two distinct segregation mechanisms, kinetic and gravity, coexist and compete in sheared granular mixtures.
- Particle shape is a critical factor determining the dominance and direction of segregation.
- The findings explain previously observed segregation reversals and provide insights into granular flow dynamics.
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