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Self-Induced Rayleigh-Taylor Instability in Segregating Dry Granular Flows
Umberto D'Ortona1, Nathalie Thomas2
1Aix Marseille Univ., CNRS, Centrale Marseille, M2P2, Marseille, France.
Physical Review Letters
|May 16, 2020
Summary
Granular materials on inclines can develop self-induced Rayleigh-Taylor (RT) instability, forming convection cells. Particle segregation drives this instability, unlike stable fluid layers.
Area of Science:
- Physics of granular materials
- Fluid dynamics
- Instability phenomena
Background:
- Granular materials flowing on inclines can exhibit complex behaviors.
- Rayleigh-Taylor (RT) instability is a known phenomenon in fluid dynamics.
- Particle size and density differences influence granular flow dynamics.
Purpose of the Study:
- To investigate the self-induced Rayleigh-Taylor (RT) instability in dry granular flows.
- To analyze the formation of convection cells from granular segregation.
- To compare RT instability in two-layer and homogeneous granular flows.
Main Methods:
- Conducted experiments with dry-granular materials on rough inclines.
- Utilized simulations to model granular flow dynamics and instability.
- Analyzed particle segregation and density gradients during flow.
Main Results:
- Observed self-induced RT instability and convection cell emergence in granular flows.
- Demonstrated that particle segregation creates unstable density gradients.
- Found that granular flows evolve into alternating bands, similar to Rayleigh-Bénard convection.
Conclusions:
- Granular segregation can spontaneously induce RT instability and sustained convection.
- Unlike fluids, granular flows form dynamic recirculation cells instead of stable layers.
- Particle segregation is the key mechanism sustaining convective motion in these granular systems.
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