scholarly journals Гидродинамические течения в микроразмерных жидкокристаллических ячейках с ориентационными дефектами

2018 ◽  
Vol 60 (9) ◽  
pp. 1834
Author(s):  
А.В. Захаров

AbstractThe effect of the orientational defect (OD) on the formation process of a vortical flow v ( t , r ), emerging in a microsized liquid crystal (LC) cell under the action of a focused laser radiation, was studied within the nonlinear generalization of the classical Ericksen–Leslie theory by numerical methods, considering the thermomechanical contributions to both the stress tensor and viscous torque, that acts on the unit volume of the liquid crystal phase (LC phase). The analysis of the obtained results showed that the vortical flow, rotating clockwise, is generated in a “defect” LC cell close to the OD, with the OD, placed on the lower bounding surface, on which the laser radiation was focused. The rotational velocity of this flow is two orders of magnitude greater than the rotational velocity of the vortex, which is generated in a “pure” LC cell at the same conditions and rotates anticlockwise.

2018 ◽  
Vol 60 (7) ◽  
pp. 1431
Author(s):  
А.В. Захаров

AbstractA theoretical description of the process of formation of vortex flows v ( t , r ) and the evolution of the director field $$\hat n$$ n ^ in microliter liquid crystal (LC) volumes with a free surface under the influence of a temperature gradient ∇ T ( t , r ), which is initiated by focused laser radiation, has been proposed. Thermomechanical contributions to both the stress tensor and viscous moment which are acting per unit volume of the LC phase were taken into account in the framework of the nonlinear generalization of the classical Ericksen−Leslie theory, which allowed describing the origin and formation of vortex flows in nematics formed by 4-n-pentyl- 4'-cyanobiphenyl molecules. Various hydrodynamic modes of vortex formation in microsized LC volumes under the action of focused laser radiation have been investigated by numerical methods.


2020 ◽  
Vol 62 (6) ◽  
pp. 965
Author(s):  
Izabela Sliwa ◽  
А.В. Захаров

Abstract Several scenarios of formation of hydrodynamic flows in nanoscale planar-oriented liquid-crystal (POLC) channels are described by numerical methods within nonlinear generalization of the classical Ericksen–Leslie theory, which allows for consideration of thermomechanical contributions both to the expression for shear stress and the equation of entropy balance. A vortex flow can eventually be formed in a nanoscale POLC channel as a result of the formation of both temperature gradient ∇ T (in the initially uniformly heated POLC channel under focused laser irradiation) and director field gradient $$\nabla {\mathbf{\hat {n}}}$$ (under a static electric field arising in the natural way at the LC phase/solid interface) and due to the interaction between ∇ T and $$\nabla {\mathbf{\hat {n}}}$$ .


2019 ◽  
Vol 61 (6) ◽  
pp. 1197
Author(s):  
А.В. Захаров

AbstractIn this paper, we described numerically several scenarios of formation of vortex flows (VF) in microsized hybrid-oriented liquid crystal (HOLC) channels with orientation defects using a nonlinear generalization of the classical Ericksen–Leslie theory that allows taking into account termomechanical contribution, both in the expression for the shear stress and in the entropy balance equation. An analysis of the numerical results showed that there are two or one vortices in the HOLC channel although two vortices directed towards each other are generated at the initial stage of the VT formation Thermomechanically Excited Vortical Flow.


2002 ◽  
Vol 80 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
B Henrissat ◽  
G K Hamer ◽  
M G Taylor ◽  
R H Marchessault

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material


ChemPhysChem ◽  
2012 ◽  
Vol 13 (1) ◽  
pp. 1-1 ◽  
Author(s):  
Dong Chen ◽  
Michael-Scott Heberling ◽  
Michi Nakata ◽  
Loren E. Hough ◽  
Joseph E. Maclennan ◽  
...  

2017 ◽  
Vol 5 (30) ◽  
pp. 7452-7457 ◽  
Author(s):  
Marc D. Harjung ◽  
Christopher P. J. Schubert ◽  
Friederike Knecht ◽  
Jan H. Porada ◽  
Robert P. Lemieux ◽  
...  

Two new examples of the lyotropic analog to the thermotropic ferroelectric SmC* phase were found recently.


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