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Dynamical Collective Memory in Fluidized Granular Materials
A Plati1, A Baldassarri2, A Gnoli2
1Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, 00185, Rome, Italy.
Physical Review Letters
|August 7, 2019
Summary
A simulation reveals a collective rotational mode in vibrated granular media, explaining probe superdiffusion at high densities and low temperatures. This persistent motion drives unexpected long-time behavior in granular systems.
Area of Science:
- Physics
- Soft Matter Physics
- Granular Materials
Background:
- Rotational diffusion of probes in vibrated granular media exhibits complex behaviors, including superdiffusion.
- Experimental limitations hinder detailed investigation of the host granular medium's properties.
Purpose of the Study:
- To quantitatively reproduce experimental observations of probe diffusion in granular media using simulations.
- To investigate the underlying properties of the host granular medium responsible for the observed phenomena.
Main Methods:
- Development of a simulation model to replicate experimental results.
- Analysis of granular medium properties, including collective rotational modes and dynamical heterogeneity.
Main Results:
- The simulation successfully reproduced experimental observations of probe diffusion, from dilute gas to dense liquid-like behavior.
- Discovery of a persistent collective rotational mode in the host granular medium at high densities and low granular temperatures.
- Identification of this collective rotation as the cause of the probe's superdiffusive behavior at large times.
Conclusions:
- A persistent collective rotational mode in granular media is responsible for probe superdiffusion.
- This mode emerges at high densities and low granular temperatures, involving slow, direction-switching rotations.
- The study highlights the interplay between collective motion, dynamical heterogeneity, and anomalous diffusion in granular systems.
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