Dynamic coupling between a multistable defect pattern and flow in nematic liquid crystals confined in a porous medium

TL;DR

This study uses lattice Boltzmann simulations to explore how flow influences and can control multistable defect patterns in nematic liquid crystals within porous media, revealing cyclic defect motions and flow-dependent control of defect configurations.

Contribution

It demonstrates the dynamic coupling between defect patterns and flow in nematic liquid crystals confined in porous media, highlighting flow control of defect configurations.

Findings

Defects are pinned at low flow speeds.

Defects exhibit cyclic motions at higher flow speeds.

Flow can be used to control defect patterns.

Abstract

When a nematic liquid crystal is confined in a porous medium with strong anchoring conditions, topological defects, called disclinations, are stably formed with numerous possible configurations. Since the energy barriers between them are large enough, the system shows multistability. Our lattice Boltzmann simulations demonstrate dynamic couplings between the multistable defect pattern and the flow in a regular porous matrix. At sufficiently low flow speed, the topological defects are pinned at the quiescent positions. As the flow speed is increased, the defects show cyclic motions and nonlinear rheological properties, which depend on whether or not they are topologically constrained in the porous networks. In addition, we discovered that the defect pattern can be controlled by controlling the flow. Thus, the flow path is recorded in the porous channels owing to the multistability of the defect patterns.