Impact of the induced nematohydrodynamics over the Freedericksz transition limit

Abstract

Liquid crystals (LC) are highly sensitive to the external field. If any external (electric or magnetic) field is applied to the LC domain beyond a critical strength, the reorientation of the molecules takes place and attains a new equilibrated state, aligning to the direction of the applied external field, known as the Fréedericksz transition. This phenomenon is widely used for optical switching in display devices and dynamic field-induced optoelectronic applications. In this work, we investigate the role of induced (nemato-)hydrodynamics by the LC field reorganization on the dynamics of the LC alignment on account of the Fréedericksz transition. The three-dimensional nematic field dynamics is modeled using the Beris–Edwards framework, minimizing the Landau de-Genes free energy, and coupled to the associated fluid flow profile. Previous studies on the LC dynamics is based on the nematic relaxation alone without the impact of the hydrodynamics. This is a reasonable approximation in the limit of the high elastic (material) constant of the LC, but not true otherwise. The LC response is delayed with the increase in Ericksen number since the local flow effect significantly influence the dynamic behavior of the nematic field. The work results are helpful in understanding the role of hydrodynamics on the LC field transition and related to the optimal switching frequency of the electrical signals, which affect the refresh rate of the LC-based display systems.