Directional clogging and phase separation for disk flow through periodic and diluted obstacle arrays

Area of Science:

• Physics
• Materials Science
• Statistical Mechanics

Background:

• Understanding granular flow and jamming phenomena is crucial in various scientific and industrial applications.
• Collective behavior in disordered systems often exhibits complex emergent properties.

Purpose of the Study:

• To investigate the phenomenon of collective disk flow through an obstacle array.
• To analyze the influence of driving direction, disk density, obstacle size, and dilution on flow dynamics and clogging.
• To characterize the nature of clogged states and their transitions.

Main Methods:

• Computer simulations modeling disk flow through a square obstacle array.
• Systematic variation of parameters including disk density, driving angle, obstacle size, and obstacle dilution.
• Analysis of average disk velocity, clogging formation, and depinning transitions.

Main Results:

• At low densities, flow is unobstructed; at higher densities, flow velocity decreases and becomes angle-dependent.
• Heterogeneous clogged states (dense regions coexisting with empty ones) form at specific driving angles, reducing or halting flow.
• Clogged states are dynamic and can be broken by altering the driving angle; uniform clogging observed for large obstacles.
• Depinning transitions and intermittent motion occur within clogged phases as driving force increases.
• Clogging is robust to obstacle dilution, forming system-spanning clusters until a critical dilution level is reached.

Conclusions:

• Collective disk flow exhibits density-dependent clogging, sensitive to driving direction and obstacle geometry.
• Fragile, heterogeneous clogged states can be controlled by external parameters like driving angle.
• The study reveals distinct clogging regimes based on obstacle size and highlights the robustness and limits of clogging under dilution.