Macroscopic liquid-state molecular hydrodynamics

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Molecular hydrodynamics in liquids are challenging to study directly at the molecular scale.
• Granular materials offer potential as macroscopic analogs for molecular systems.
• Previous models have not fully bridged granular dynamics with molecular hydrodynamics.

Purpose of the Study:

• To establish granular materials as experimental analogs for liquid-state molecular hydrodynamics.
• To develop new macroscopic statistical mechanics models for granular systems.
• To connect observable granular dynamics to fundamental hydrodynamic processes.

Main Methods:

• Experimental studies of confined, high-restitution granular piles under low-amplitude vibration.
• Theoretical modeling recasting microscale statistical mechanics into a self-consistent macroscale form.
• Derivation of continuum equations for viscous, liquid-like granular flow from the new models.

Main Results:

• Observed granular dynamics (single-grain and collective) that mimic molecular liquid behaviors.
• Demonstrated hydrodynamic organization on near-collision time scales.
• Showcased long-time scale excitation of collective modes and emergence of viscous flow.

Conclusions:

• Vibrated granular systems provide accessible analogs for studying liquid hydrodynamics.
• Novel macroscopic models successfully link granular physics to molecular hydrodynamic principles.
• The derived continuum equations allow for physically consistent interpretation of granular flow.