Nematodynamics and structures in junctions of cylindrical micropores

ABSTRACT

We explore equilibrium structures and flow-driven deformations of nematic liquid crystals confined to 3D junctions of cylindrical micropores with homeotropic surface anchoring. The topological state of the nematic ordering field in such basic unit of porous networks is controlled by nematic orientation profiles in individual pores, anchoring frustration along the edges of joining pores and coupling to the material flow field. We numerically investigate formation of the flow-aligned configurations in single cylindrical pores and pore junctions. Depending on the arrangement of inlet and outlet flows in the junction, we demonstrate existence of numerous stationary nematic configurations, characterised by specific bulk defects and surface disclinations along joining edges. Observed bulk defects are nonsingular escaped structures, disclinations in the form of loops or disclination lines pinned to the joining edges of the pores. Furthermore, we show examples of defect dynamics during the flow-induced topological transformations.

GRAPHICAL ABSTRACT

KEYWORDS:

• Microfluidics
• nematodynamics
• liquid crystals
• confined nematics
• topological defects
• flow
• porous networks

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge funding from Slovenian Research Agency ARRS through grants [P1-0099, J1-7300, L1-8135], and USAF AFRL EOARD research project Nematic Colloidal Tilings as Tunable Soft Metamaterials [grant no. FA9550-15-1-0418].