Phase separation and state oscillation of active inertial particles

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Active matter systems exhibit complex collective behaviors not seen in equilibrium systems.
• Active Brownian particles (ABPs) show clustering and motility-induced phase separation in the overdamped limit.
• The role of inertia in these collective behaviors remains less explored.

Purpose of the Study:

• Investigate the impact of inertia on active matter collective behavior.
• Analyze phase separation and emergent dynamics in an Active Inertial Particle (AIP) model.
• Compare underdamped AIP behavior to overdamped ABP systems.

Main Methods:

• Simulations of the Active Inertial Particle (AIP) model.
• Focus on the underdamped regime, incorporating inertial effects.
• Analysis of particle motility, phase separation, and oscillatory dynamics.

Main Results:

• Inertia suppresses phase separation by reducing motility and increasing time delays after collisions.
• Observed oscillatory behavior between phase-separated and homogeneous states due to inertia-induced collective motion.
• Oscillations arise from momentum transfer within active clusters, similar to shape-anisotropic ABP systems.
• Power spectral density exhibits a power law with an exponent near -2.5 at high frequencies.

Conclusions:

• Particle inertia significantly alters collective dynamics in active matter systems.
• Inertia leads to novel oscillatory behaviors not present in the overdamped limit.
• The findings highlight the importance of considering inertial effects for a complete understanding of active matter.