Flow-induced disclination lines in nematic liquid crystals

We present a numerical study, based on the lattice Boltzmann method, of nematic liquid crystals flowing in microfluidic channels. We show that disclination lines are generated by the interaction between flow and anchoring conditions of the channel walls. In particular, we observe nucleations of pairs of twist disclinations in those regions of the channel where the elastic aligning forces, resulting from the anchoring conditions, are perpendicular to the local shear plane of the flow. The newly formed disclinations either persist or annihilate, depending on the overall configuration of the director field in the channel. We study the behavior at boundaries between different anchoring conditions and describe the formation of flow-induced disclination arcs. We show that the numerical model correctly reproduces the results of an experimental study [Agha and Bahr, Soft Matter 12, 4266 (2016)1744-683X10.1039/C5SM03092G], thereby validating our numerical results.