Abstract
We describe a coarse-grained Landau-de Gennes model of liquid crystals (LCs) including hydrodynamics based on the Beris-Edwards equations. The model is employed to study the impact of large colloids on the long range LC defect structure in the cholesteric LC blue phases. 'Large' here means that the particle size is comparable to the cholesteric pitch, the length scale on which the LC order undergoes a helical twist. We investigate the case of a single particle, with either normal or degenerate planar anchoring, placed initially in an equilibrium blue phase LC. It is found that in some cases, well defined steady disclination structure emerges at the particle surface, while in other cases no clear steady state is reached inthesimulations,anddisclinationreorganisationappearstoproliferatethroughthebulkLC. These systems are of potential interest in the context of using LCs to template self-assembly of colloid structure, e.g., for opto-electronic devices. Computationally, we demonstrate a parallel approach using mixed message-passing and threaded model on graphical processing units allows effective and efficient progress for this problem.
Highlights
Liquid crystals (LCs) are both interesting and useful complex fluids
Shear flow tends to rotate the rigid LC molecules, while hydrodynamics influences processes such as phase separation kinetics and is central in phenomena such as permeation flow
We concentrate on simulation results for the behaviour of a single colloid in cubic BPI, and in particular the defect structure formed by particles which are relatively large compared to the cholesteric pitch
Summary
Liquid crystals (LCs) are both interesting and useful complex fluids. Typically composed of rod-like or disc-like molecules of a few nanometres in size, long range orientational order. Simulation of colloids in bulk BPs [28,30] have been undertaken, along with work on colloids confined in thin layers [22,29,32] These existing studies are mostly limited to the case where the colloidal particles are relatively small compared with the cholesteric pitch We concentrate on simulation results for the behaviour of a single colloid in cubic BPI, and in particular the defect structure formed by particles which are relatively large compared to the cholesteric pitch (and the BP lattice constant). This regime has not been accessible to simulation before. A summary and some discussion of future directions is given in the final section
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