Generalized drift velocity of a cholesteric texture in a temperature gradient

Area of Science:

• Liquid crystal physics
• Soft matter science
• Thermodynamics

Background:

• Cholesteric liquid crystals exhibit complex textures.
• Temperature gradients can induce material flow and texture dynamics.
• Understanding drift velocity is crucial for predicting texture behavior.

Purpose of the Study:

• To develop a general method for calculating drift velocity in cholesteric textures subjected to temperature gradients.
• To differentiate drift mechanisms for Translationally Invariant Configurations (TICs) and localized structures (droplets, fingers).
• To identify the contributions of thermomechanical coupling and temperature-dependent material properties to drift.

Main Methods:

• Theoretical calculation of drift velocity without backflow effects.
• Analysis of cholesteric textures including TICs, droplets, and fingers.
• Incorporation of Leslie's thermomechanical coupling and Akopyan-Zel'dovich terms.
• Investigation of temperature variations in elastic constants and transverse gradients.

Main Results:

• Drift velocity calculation for TICs and localized cholesteric structures under thermal gradients.
• TICs and droplets exhibit rotational drift, while fingers show translational drift.
• For TICs, drift arises from Leslie and Akopyan-Zel'dovich terms.
• Localized structures show additional drift due to temperature-dependent elastic constants and transverse gradients.

Conclusions:

• A unified method is established for calculating drift velocity in cholesteric textures under thermal stress.
• The study elucidates distinct drift behaviors (rotational vs. translational) based on texture type.
• Both classical thermomechanical coupling and novel mechanisms contribute to drift, offering deeper insights into cholesteric dynamics.