Traveling waves at the surface of active liquid crystals

Area of Science:

• Soft Matter Physics
• Non-equilibrium Systems
• Liquid Crystal Dynamics

Background:

• Active liquid crystals are systems that consume energy to generate nonequilibrium stresses and dynamical steady states.
• Microtubule suspensions powered by kinesin motor proteins are a key example, exhibiting chaotic flows.
• Research is increasingly focused on the interfacial properties of active liquid crystals mixed with passive fluids.

Purpose of the Study:

• To derive a minimal model for the linear dynamics of the interface between an active liquid crystal and a passive fluid.
• To understand how bulk active flows influence interfacial dynamics.
• To provide a theoretical framework for connecting experimental observations with continuum theories.

Main Methods:

• Derivation of a minimal continuum model.
• Coupling of interface height and nematic director at the interface.
• Comparison of model predictions with numerical simulations and experimental data.

Main Results:

• The minimal model qualitatively captures the interface dynamics driven by bulk active flows.
• The model successfully reproduces the dynamical structure factor from numerical simulations.
• The model's predictions align with the qualitative form of the wave dispersion relation observed in experiments.

Conclusions:

• A minimal model effectively describes the linear dynamics of active/passive liquid crystal interfaces.
• Interfacial dynamics can be understood through coupled equations for interface height and nematic director.
• This model serves as a bridge between theoretical descriptions and experimental findings in active matter systems.