Flow-induced delayed Freedericksz transition

Mottram, Nigel and McKay, Geoffrey and Brown, Carl and Russell, Craig and Sage, Ian (2016) Flow-induced delayed Freedericksz transition. Physical Review E, 93 (3). 030701(R). ISSN 2470-0053 (https://doi.org/10.1103/PhysRevE.93.030701)

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We demonstrate that a compact manometer experiment allows direct observation of a delay to the classical electric field induced Freedericksz transition produced by flow in a highly dispersive nematic liquid crystal layer. The Ericksen-Leslie equations are used to show that a flow aligning torque generated in the nematic layer under Poiseuille flow competes with the orthogonal electric field re-orientation torque. This model fully reproduces the experimental results using only self-consistently determined viscosity values, and predicts a more generally applicable expression for the dependence of the delay Ec ∝√(ζ/Δχe) on the shear rate ζ and on the electric susceptibility anisotropy Δχe..