Mazza_manuscript.pdf (17.86 MB)
0/0

Emergent biaxiality in nematic microflows illuminated by a laser beam

Download (17.86 MB)
journal contribution
posted on 17.09.2019 by Jan-Christoph Eichler, Robert A Skutnik, Anupam Sengupta, Marco Mazza, Martin Schoen
Anisotropic fluids (e.g. liquid crystals) offer a remarkable promise as optofluidic materials owing to the directional, tunable, and coupled interactions between the material, flow, and the optical fields. Here we present a comprehensive in silico treatment of this anisotropic interaction by performing nonequilibrium molecular dynamics simulations. We quantify the response of a nematic liquid crystal (NLC) undergoing a Poiseuille flow in the Stokes regime, while being illuminated by a laser beam incident perpendicular to the flow direction. We adopt a minimalistic model to capture the interactions, accounting for two features: first, the laser heats up the NLC locally; and second, the laser polarises the NLC and exerts an optical torque that tends to reorient molecules of the nematic phase. Because of this reorientation the liquid crystal exhibits small regions of biaxiality, where the nematic director is one symmetry axis and the axis of rotation for the reorientation of the molecules is the other one. We find that the relative strength of the viscous and the optical torques mediates the flow-induced response of the biaxial regions, thereby tuning the emergence, shape and location of the regions of enhanced biaxiality. The mechanistic framework presented here promises experimentally tractable routes toward novel optofluidic applications based on material-flow-light interactions.

Funding

ATTRACT Investigator Grant of the Luxembourg National Research Fund [grant number A17/MS/11572821/MBRACE].

History

School

  • Science

Department

  • Mathematical Sciences

Published in

Molecular Physics

Volume

117

Issue

23-24

Pages

3715-3733

Publisher

Informa UK Limited

Version

AM (Accepted Manuscript)

Rights holder

© Taylor and Francis

Publisher statement

This is an Accepted Manuscript of an article published by Taylor & Francis in Molecular Physics on 16/09/2019 available online: https://doi.org/10.1080/00268976.2019.1663286

Acceptance date

27/08/2019

Publication date

2019-09-16

Copyright date

2019

ISSN

0026-8976

eISSN

1362-3028

Language

en

Depositor

Dr Marco Mazza

Exports