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Bouncing, rolling, energy flows, and cluster formation in a two-dimensional vibrated granular gas
Gabriel Pérez-Ángel1, Yuri Nahmad-Molinari
1Departamento de Física Aplicada, CINVESTAV del IPN, Apartado Postal 73 Cordemex, 97310 Mérida, Yucatán, México.
Granular gases spontaneously form crystalline clusters by segregating into "bouncers" and "rollers." The dominant group forms clusters, compressed by the other, enabling controlled cluster formation.
Area of Science:
- Physics
- Materials Science
- Complex Systems
Background:
- Granular materials exhibit complex behaviors under external stimuli.
- Understanding pattern formation in vibrated granular systems is crucial for materials science.
Purpose of the Study:
- Investigate the formation of crystalline clusters in a 2D vibrated granular gas using 3D simulations.
- Identify the underlying mechanisms driving cluster formation and segregation.
Main Methods:
- Utilized fully 3D simulations for a 2D sinusoidally vibrated granular gas.
- Analyzed grain dynamics, categorizing them into 'bouncers' and 'rollers'.
- Monitored clustering using coordination number and hexatic order parameter ψ(6).
Main Results:
- Observed spontaneous segregation into 'bouncers' and 'rollers' dynamical modes.
- The majority dynamical mode forms clusters, compressed by the minority mode acting as a higher pressure gas.
- Controlled formation of either roller or bouncer clusters is possible.
- Single-mode gases show weak density fluctuations; mixed modes lead to segregation and dual clustering.
- Roller-bouncer collisions increase horizontal kinetic energy; other collisions decrease it.
Conclusions:
- Spontaneous segregation into distinct dynamical modes drives crystalline cluster formation in vibrated granular gases.
- The interplay between 'bouncers' and 'rollers' allows for tunable cluster formation.
- Friction with the substrate is identified as the primary sink for horizontal energy in these systems.
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