Hydrodynamic model for a dynamical jammed-to-flowing transition in gravity driven granular media

Area of Science:

• Physics of granular materials
• Fluid dynamics
• Non-Newtonian flow

Background:

• Granular materials exhibit complex flow behaviors, often mimicking fluids under specific conditions.
• Understanding the transition from static (jammed) to dynamic (flowing) states is crucial for predicting material transport and behavior.
• Previous models often rely on solid friction to explain flow cessation, but this study explores alternative mechanisms.

Purpose of the Study:

• To investigate the physics governing granular chute flow down an inclined plane.
• To develop and apply a hydrodynamic model to predict the jammed-to-flowing transition.
• To identify the key parameters influencing flow behavior, such as inclination angle and layer thickness.

Main Methods:

• Utilized a hydrodynamic model previously validated for granular Couette flow.
• Simulated granular material flow on an inclined plane with varying inclination angles (theta).
• Analyzed the role of mean and fluctuating velocity coupling in driving the flow transition.

Main Results:

• The hydrodynamic model successfully predicts a transition from a jammed state to a flowing state as the inclination angle increases.
• Flow is predicted for granular layers thicker than a critical value, H(stop)(theta), which depends on the inclination angle.
• The model demonstrates that velocity coupling, not solid friction, can drive the jammed-to-flowing transition.

Conclusions:

• A hydrodynamic model without solid friction can accurately capture the jamming transition in granular chute flow.
• The critical layer thickness for flow cessation is angle-dependent and linked to velocity coupling dynamics.
• This study provides a new theoretical framework for understanding granular material flow on inclined surfaces.