Liquid-crystal pumping in a cylindrical capillary with radial temperature gradient

Abstract

Dynamic field pumping principle has been developed utilizing the interactions of both the director and velocity fields and a temperature gradient inverted deltaT. The orientational dynamics in the hybrid-oriented liquid-crystal (HOLC) microvolume confined between two infinitely long coaxial cylinders under the influence of the radially directed inverted deltaT has been investigated. We have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across the HOLC cavity between two cylinders under the influence of inverted deltaT, when the liquid-crystal cavity is heated both from outer (inner) to inner (outer) bounding cylinders. Calculations show that under the influence of inverted deltaT the initially quiescent HOLC drop settles down to a stationary flow regime, with the horizontal u(st)(r) component of velocity. The effects of inverted deltaT , of the character of the preferred anchoring of the average molecular direction to the restricted cylinders, and of the size of the HOLC cavity on magnitude and direction of hydrodynamic flow--for a number of hydrodynamic regimes--has been investigated.

Heat Driven Flows in Microsized Nematic Volumes: Computational Studies and Analysis

“…The objective of this section is to analyze the response of the nematic phase confined in the cylindrical micro cavity between two horizontal coaxial cylinders under the influence of the temperature gradient ∇T directed from the inner (outer) cooler (warmer) to outer (inner) warmer (cooler) cylinders [28]. Therefore, we are primarily interested here in describing how the temperature gradient across the microvolume cavity between two coaxial cylinders can produce the hydrodynamic flow v. It has been treated in the framework of the classical Ericksen-Leslie theory [16,17], supplemented by the thermomechanical correction of shear stress [7,15], and the entropy balance equation [18].…”

Влияние электрического поля и градиента температуры на формирование гидродинамичеcкого течения в тонком нематическом капилляре

“…еще один параметр системы. В случае малых градиентов температуры ∇χ по сечению ЖК-полости безразмерное уравнение баланса энтропии может быть записано в виде [15]…”

Nonmechanical pumping principle in submicrosized devices

“…In this case, the direction of hydrodynamic flow v is influenced by both the direction of heat flow and the character of the preferred anchoring of the average molecular direction n on the bounding surfaces. [6][7][8][9][10] On the other hand, in LC cells where director anchorings on the two bounding surfaces are the same, i.e., both strongly homeotropic or homogeneous, the LC microvolume remains quiescent under the influence of the temperature gradient. If homogeneously aligned LC ͑HALC͒ sample confined in a microvolume between two horizontal coaxial cylinders and subjected to both a temperature gradient ٌT, with the inner cylinder kept at a lower temperature than the outer one, and radially applied electric field E, then the microvolume HALC material settles down to a stationary flow regime in the horizontal direction.…”

“…[6][7][8][9][10][11] It has been shown that in the case of a hybrid-oriented LC cell, the magnitude of the hydrodynamic flow v excited by a temperature gradient ٌT is proportional to the tangential component of the thermomechanical stress tensor ͑ST͒ ij tm . In this case, the direction of hydrodynamic flow v is influenced by both the direction of heat flow and the character of the preferred anchoring of the average molecular direction n on the bounding surfaces.…”