Pressure dynamics in the bottleneck flow of self-propelled particles

Area of Science:

• Physics
• Soft Matter Physics
• Complex Systems

Background:

• Understanding the behavior of self-propelled particles is crucial in various fields, including robotics and biology.
• Flow dynamics through constrictions are fundamental to granular materials and active matter systems.
• Clogging phenomena in granular flow and active matter present complex challenges in predicting system behavior.

Purpose of the Study:

• To experimentally investigate pressure dynamics of self-propelled particles flowing through narrow passages.
• To differentiate pressure behavior during free flow versus clogging events.
• To correlate pressure evolution with particle exit times and system reorganization.

Main Methods:

• Experimental setup involving self-propelled particles and a narrow passage.
• Measurement of pressure fluctuations and particle exit times.
• Analysis of pressure dependence on crowd size during flow and clogging.

Main Results:

• Flowing particle ensembles exhibit pressure fluctuations independent of crowd size, indicating local orifice control.
• Clogged systems show increased pressure with larger crowd sizes, highlighting collective effects.
• Clog resolution leads to a sudden pressure drop followed by sustained growth with a square-root dependence, suggesting structural aging.

Conclusions:

• Pressure dynamics are governed by different mechanisms during free flow and clogging.
• Collective behavior significantly influences pressure in clogged systems.
• The observed pressure evolution post-clogging supports theories of structural aging in self-propelled particle systems.