Active nematic gel with quenched disorder.

Area of Science:

• Soft Matter Physics
• Active Matter Systems
• Hydrodynamics

Background:

• Active nematics are systems of self-propelled particles with orientational order.
• Quenched disorder can significantly impact the ordering kinetics of such systems.
• Incompressible fluids introduce hydrodynamic interactions and fluctuations.

Purpose of the Study:

• To investigate the combined effects of quenched disorder and fluid environments on the ordering dynamics of two-dimensional active nematics.
• To understand how quenched disorder influences defect dynamics and system kinetics.
• To determine the relative importance of fluid fluctuations versus quenched disorder.

Main Methods:

• Development of coarse-grained hydrodynamic equations of motion for density, orientation, and flow fields.
• Numerical simulations to study defect dynamics and ordering kinetics.
• Systematic variation of quenched disorder strength.

Main Results:

• Finite quenched disorder was found to slow down the ordering process.
• The presence of an incompressible fluid induced significant fluctuations in the orientation field, further hindering ordering.
• Fluid-induced orientation fluctuations were dominant, reducing the impact of quenched disorder.
• The effect of disorder was similar for both contractile and extensile active stresses.

Conclusions:

• Fluid-induced fluctuations play a dominant role in active nematic systems, often overshadowing the effects of quenched disorder.
• Understanding these competing factors is crucial for predicting the behavior of active gels and similar soft matter systems.
• This research provides insights into the impact of quenched disorder on the ordering kinetics of active nematics in fluid environments.