Motion transition of active filaments: rotation without hydrodynamic interactions

Area of Science:

• Soft matter physics
• Active matter dynamics
• Filamentous systems

Background:

• Active semiflexible filaments are crucial in biological systems.
• Understanding their dynamics requires considering flexibility, active forces, and interactions.
• Hydrodynamic interactions (HI) play a complex role in these systems.

Purpose of the Study:

• To investigate the dynamics of active semiflexible filaments using a bead-rod model.
• To analyze the influence of hydrodynamic interactions, active force, flexibility, and drag on filament motion.
• To elucidate the mechanisms behind different motion types and collective structure formation.

Main Methods:

• Utilized a bead-rod model to simulate filament dynamics.
• Incorporated hydrodynamic interactions (HI), active force, filament flexibility, and viscous drag.
• Analyzed transitions between translation, snaking, and rotation based on parameter variations.

Main Results:

• Identified three distinct motion types: translation, snaking, and rotation.
• Found continuous transition from translation to snaking via transverse instability.
• Observed a first-order-like transition from snaking to rotation due to symmetry breaking.
• Demonstrated that HI is not essential for snaking/rotation but expands their parameter space.
• Showed HI is essential for collective vortex emergence when maintaining rotation curvature.

Conclusions:

• Active semiflexible filaments display rich dynamics governed by flexibility and active forces.
• Hydrodynamic interactions play a subtle but crucial role in enabling collective behaviors.
• Findings offer insights into self-organization and pattern formation in active matter systems.