Rheology of distorted nematic liquid crystals

TL;DR

This paper uses lattice Boltzmann simulations to study how nematic liquid crystals with boundary anchoring distortions respond to shear and flow, revealing non-Newtonian behaviors and asymmetries near phase transitions.

Contribution

It provides the first detailed simulation-based analysis of nematic liquid crystal rheology in hybrid aligned cells under flow conditions.

Findings

Velocity profiles are strongly non-Newtonian and asymmetric due to backflow effects.

As the isotropic transition is approached, elastic distortion effects weaken.

Heating above the transition introduces asymmetry in shear band formation dynamics.

Abstract

We use lattice Boltzmann simulations of the Beris--Edwards formulation of nematodynamics to probe the response of a nematic liquid crystal with conflicting anchoring at the boundaries under shear and Poiseuille flow. The geometry we focus on is that of the hybrid aligned nematic (HAN) cell, common in devices. In the nematic phase, backflow effects resulting from the elastic distortion in the director field render the velocity profile strongly non-Newtonian and asymmetric. As the transition to the isotropic phase is approached, these effects become progressively weaker. If the fluid is heated just above the transition point, however, another asymmetry appears, in the dynamics of shear band formation.