Colloids in liquid crystals: a lattice Boltzmann study

TL;DR

This paper introduces a hybrid lattice Boltzmann method to simulate colloids in liquid crystals, validating it with nematic studies and exploring defect configurations in cholesterics for potential material control.

Contribution

A novel hybrid lattice Boltzmann algorithm for simulating colloids in liquid crystals, enabling detailed analysis of defect structures and hydrodynamics.

Findings

Drag force in nematics is highly anisotropic.

Defect configurations can be controlled by particle size and cholesteric pitch.

Stable figure-of-eight and twisted defect loops are achievable.

Abstract

We propose a hybrid lattice Boltzmann algorithm to simulate the hydrodynamics of colloidal particles inside a liquid crystalline host. To validate our algorithm, we study the static and the microrheology of a colloid in a nematic, with tangential anchoring of the director field at the particle surface, and we confirm theories and experiments showing that the drag force in a nematic is markedly anisotropic. We then apply our method to consider the case of a colloid inside a cholesteric, and with normal anchoring at the surface. We show that by tuning the ratio between particle size and cholesteric pitch it is possible to control the defect configuration around the particle, and to stabilise novel figure-of-eight or highly twisted loops close to the colloid surface.