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Subharmonic instability of a self-organized granular jet
1Institute for Multiscale Simulation, Universität Erlangen-Nürnberg, Erlangen, Germany.
Scientific Reports
|March 23, 2016
Summary
Granular matter flows can form self-organized jets. Experiments show these jets exhibit subharmonic responses to agitation, not direct frequency following.
Area of Science:
- Physics
- Fluid Dynamics
- Granular Mechanics
Background:
- Granular flows in confined geometries can exhibit complex emergent behaviors.
- Understanding self-organization in granular matter is crucial for various industrial and geophysical processes.
Purpose of the Study:
- To investigate the dynamics of self-organized jets formed by downhill granular flows.
- To analyze the frequency response of emergent jets to external sinusoidal agitation.
Main Methods:
- A quasi two-dimensional experimental setup was employed.
- Fine-grained sand was flowed within a vertically sinusoidally agitated cylinder.
Main Results:
- The emergent jet (sheet of ejecta) did not directly follow the agitation frequency.
- A subharmonic response was observed in the jet's behavior.
- The order of subharmonics depended complexly on the driving parameters.
Conclusions:
- Downhill granular flows can lead to self-organized jetting phenomena.
- The system exhibits non-linear dynamics with subharmonic frequency response.
- Further research is needed to fully characterize the complex relationship between driving parameters and subharmonic order.
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