Flow-induced delayed Freedericksz transition

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.