Controllable particle migration in liquid crystal flows

TL;DR

This paper demonstrates controllable and faster colloidal particle migration in nematic liquid crystal flows, with multiple tunable equilibrium positions influenced by elastic, hydrodynamic, and defect interactions, contrasting classical isotropic fluid behavior.

Contribution

It introduces a novel method for controlling particle positions in liquid crystal flows using pressure, revealing multiple tunable equilibria and faster migration compared to isotropic fluids.

Findings

Multiple equilibrium positions are tunable via pressure.

Particle migration is an order of magnitude faster.

Elastic and defect interactions determine particle stability.

Abstract

We observe novel positional control of a colloidal particle in microchannel flow of a nematic liquid crystal. Lattice Boltzmann simulations show multiple equilibrium particle positions, the existence and position of which are tunable using the driving pressure, in direct contrast to the classical Segre-Silberberg effect in isotropic liquids. In addition, particle migration in nematic flow occurs an order of magnitude faster. These new equilibria are determined through a balance of elastic forces, hydrodynamic lift and drag as well as order-flow interactions through the defect structure around the particle.