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Vertical ordering of rods under vertical vibration.
M Ramaioli1, L Pournin, Th M Liebling
1Mathematics Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland. marco.ramaioli@epfl.ch
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 13, 2007
Summary
Vertical vibration causes elongated particles in granular media to self-order. An energy barrier model explains this ordering, considering particle length and vibration intensity.
Area of Science:
- Physics of granular materials
- Complex systems dynamics
Background:
- Granular media with elongated particles exhibit vertical ordering under vibration.
- The role of confinement and particle shape in self-organization is not fully understood.
Purpose of the Study:
- To investigate the self-ordering of elongated particles in granular media under vertical vibration.
- To explore the influence of particle shape and vibration parameters on ordering.
- To develop a theoretical framework explaining the observed phenomena.
Main Methods:
- Pseudo-two-dimensional discrete element model (DEM) simulations.
- Quantitative analysis of void formation and particle rearrangement.
- Development of an energetic barrier model.
Main Results:
- Vertical ordering of elongated particles occurs even without side walls.
- Void filling explains why shorter rods order less effectively than longer ones.
- An optimal vibration acceleration exists for vertical ordering, dependent on particle length.
Conclusions:
- A void-filling mechanism partially explains vertical ordering and particle length dependence.
- An energetic barrier model successfully reconciles ordering with vibration acceleration and particle length.
- The model identifies three distinct regimes of particle behavior under vibration.
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