The effect of anchoring on nematic flow in channels

TL;DR

This study uses simulations to explore how anchoring boundary conditions influence nematic liquid crystal flow in channels, revealing non-linear flow behaviors and director profile transitions that could help quantify substrate anchoring.

Contribution

The paper introduces a hybrid lattice-Boltzmann simulation approach to analyze the impact of anchoring conditions on nematic flow and director configurations in microfluidic channels.

Findings

Flow rate deviates from linear Poiseuille behavior under different anchoring conditions.

A morphological transition in director profiles is identified and explained as an instability.

Changing anchoring type and strength significantly affects flow and director configurations.

Abstract

Understanding the flow of liquid crystals in microfluidic environments plays an important role in many fields, including device design and microbiology. We perform hybrid lattice-Boltzmann simulations of a nematic liquid crystal flowing under an applied pressure gradient in two-dimensional channels with various anchoring boundary conditions at the substrate walls. We investigate the relation between flow rate and pressure gradient and the corresponding profile of the nematic director, and find significant departures from the linear Poiseuille relation. We also identify a morphological transition in the director profile and explain this in terms of an instability in the dynamical equations. We examine the qualitative and quantitative effects of changing the type and strength of the anchoring. Understanding such effects may provide a useful means of quantifying the anchoring of a substrate by measuring its flow properties.