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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
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Phase diagram for inertial granular flows.
E DeGiuli1,2, J N McElwaine3, M Wyart2
1New York University, Center for Soft Matter Research, 4 Washington Place, New York, New York 10003, USA.
Physical Review. E
|August 31, 2016
Summary
Flows of hard granular materials exhibit three distinct regimes based on interparticle friction and inertial number (I). These regimes, frictionless, frictional sliding, and rolling, are defined by energy dissipation mechanisms and impact flow behavior.
Area of Science:
- Physics of granular materials
- Rheology
- Statistical mechanics
Background:
- Granular material flow is governed by interparticle friction (μp) and inertial number (I).
- Understanding flow regimes is crucial for predicting jamming transitions and material behavior.
Purpose of the Study:
- To map the phase diagram of dense inertial flow for spherical particles.
- To identify and characterize distinct flow regimes based on energy dissipation.
Main Methods:
- Numerical simulations of hard granular materials.
- Analysis of energy dissipation mechanisms (collisional, sliding friction, rolling).
- Derivation of scaling relations and phase boundaries.
Main Results:
- Identified three flow regimes: frictionless, frictional sliding, and rolling, for 10⁻⁴≲I≲10⁻¹.
- Observed nonmonotonic behavior in velocity fluctuations and stress ratio with increasing μp.
- Found that macroscopic friction (μ(I)) increases with I in the frictional sliding regime due to enhanced collisional dissipation.
Conclusions:
- The phase diagram reveals distinct flow behaviors governed by energy dissipation.
- Velocity fluctuations and stress ratio exhibit transitions between regimes.
- Scaling relations connect microscopic properties to macroscopic flow behavior, particularly in the experimentally relevant frictional sliding regime.
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