Pattern transition, microstructure, and dynamics in a two-dimensional vibrofluidized granular bed

Area of Science:

• Granular physics
• Nonlinear dynamics
• Statistical mechanics

Background:

• Understanding granular material behavior under vibration is crucial for industrial processes.
• Previous studies have identified distinct states but lacked detailed transition dynamics.

Purpose of the Study:

• To investigate the transition scenarios and microstructural dynamics of granular materials in a 2D vibrofluidized bed.
• To characterize the evolution from solid to gas-like states under varying vibration parameters.

Main Methods:

• Experiments conducted in a 2D monolayer vibrofluidized bed of glass beads.
• Systematic variation of shaking intensity (Γ) and amplitude (A/d).
• Analysis of particle microstructure and dynamics using density, temperature profiles, and pair correlation functions.

Main Results:

• Observed a transition sequence: solid bed (SB) → bouncing bed (BB) → Leidenfrost state (LS) → 2-roll convection → 1-roll convection → granular gas.
• Identified multiroll transition and subsequent transition to granular gas.
• BB state exhibits hexagonal packing; LS state shows liquid-like clustering.
• Discovered sinusoidal oscillations in LS and BB states, matching external shaking frequency.

Conclusions:

• The BB→LS transition critical intensity follows a power-law dependence on particle loading and shaking amplitude.
• The granular Leidenfrost state is a period-1 wave, similar to the bouncing bed state.
• This work provides insights into pattern formation and phase transitions in vibrated granular systems.