Coarsening dynamics of binary liquids with active rotation

Area of Science:

• Physics
• Soft Matter Physics
• Complex Systems

Background:

• Active matter systems exhibit emergent collective behaviors like pattern formation and phase separation.
• Collective behaviors of linearly self-propelled particles are well-studied, but active rotating particles are less understood.
• Previous simulations showed active rotation induces phase separation in counter-rotating particle mixtures.

Purpose of the Study:

• To investigate the influence of self-generated convective flows on the coarsening dynamics of actively rotating binary liquids.
• To explore new dynamical behaviors arising from active rotation and frictional interactions.
• To compare continuum model predictions with discrete particle-based simulations.

Main Methods:

• Utilized a phenomenological hydrodynamic model combining Cahn-Hilliard and Navier-Stokes equations.
• Introduced active rotation effects via an additional force in Navier-Stokes equations based on particle concentration gradients.
• Employed discrete, particle-based simulations to validate continuum model findings.

Main Results:

• Observed new dynamical behaviors including "active coarsening" driven by self-generated flows.
• Identified the emergence of self-propelled "vortex doublets" in actively rotating binary liquids.
• Confirmed qualitative agreement between continuum model predictions and particle-based simulations.

Conclusions:

• Active rotation in binary liquids leads to unique phase separation and coarsening dynamics distinct from linear active matter.
• Self-generated flows and vortex structures are key emergent phenomena in these systems.
• Findings offer insights into creating complex dissipative structures in distributedly actuated active materials.