scholarly journals Сдвиговой режим формирования градиента температуры в тонком нематическом канале

2019 ◽  
Vol 61 (4) ◽  
pp. 779
Author(s):  
А.В. Захаров ◽  
С.В. Пасечник ◽  
Д.В. Шмелева
Keyword(s):  
Shear Stress ◽  
Liquid Crystal ◽  
Numerical Methods ◽  
Temperature Gradient ◽  
Thermal Insulation ◽  
Constant Temperature ◽  
Balance Equation ◽  
Set Up ◽  
Boundary Surfaces ◽  
Upper Boundary

AbstractIt has been shown by means of numerical methods, in the framework of the classical Ericksen-Leslie theory, together with accounting the entropy balance equation, how a temperature gradient, in the initially uniformly heated a hybrid-oriented liquid crystal (HOLC) channel, may set up under action of a shear stress (SS). The cases of complete and partial thermal insulation of one of the boundary surfaces of the HOLC are analyzed under the condition that a constant temperature is kept on the rest boundaries. It also has been shown how to heat up the planarly oriented upper boundary of the HOLC channel under the influence of the SS and, thereby, to form the temperature gradient across the HOLC channel.

scholarly journals Лазерная нанофлюидика жидких кристаллов

2020 ◽  
Vol 62 (6) ◽  
pp. 965
Author(s):  
Izabela Sliwa ◽  
А.В. Захаров
Keyword(s):  
Shear Stress ◽  
Liquid Crystal ◽  
Numerical Methods ◽  
Temperature Gradient ◽  
Electric Field ◽  
Vortex Flow ◽  
Static Electric Field ◽  
Director Field ◽  
Nonlinear Generalization ◽  
Natural Way

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 $$\nabla {\mathbf{\hat {n}}}$$ .

scholarly journals Термомеханический режим формирования вихревых течений в гибридно ориентированном нематическом канале

2019 ◽  
Vol 61 (6) ◽  
pp. 1197
Author(s):  
А.В. Захаров
Keyword(s):  
Shear Stress ◽  
Liquid Crystal ◽  
Balance Equation ◽  
Numerical Results ◽  
Vortical Flow ◽  
Vortex Flows ◽  
Entropy Balance ◽  
Initial Stage ◽  
Nonlinear Generalization

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.

A Heparin-coated Circuit Maintains Platelet Aggregability in Response to Shear Stress in an In Vitro Model of Cardiopulmonary Bypass

1998 ◽  
Vol 80 (09) ◽  
pp. 437-442 ◽  
Author(s):  
I. Hioki ◽  
K. Onoda ◽  
T. Shimono ◽  
H. Shimpo ◽  
K. Tanaka ◽  
...  
Keyword(s):  
Shear Stress ◽  
Cardiopulmonary Bypass ◽  
Membrane Skeleton ◽  
Platelet Glycoprotein ◽  
Platelet Surface ◽  
Platelet Aggregability ◽  
Vitro Model ◽  
Platelet Defects ◽  
Set Up

SummaryAlterations in platelet aggregability may play a role in the pathogenesis of qualitative platelet defects associated with cardiopulmonary bypass (CPB). We circulated fresh heparinized whole blood through tubing sets coated with heparin (C group, n = 10) and through non-coated sets (N group, n = 10) as a simulated CPB circuit. Shear stress (108 dyne/cm2)-induced platelet aggregation (hSIPA), plasma von Willebrand factor (vWF) activity and platelet glycoprotein (GP) Ib expression were measured, before, during, and after this in vitro set up of circulation. In the two groups, the extent of hSIPA significantly decreased during circulation and was partially restored after circulation. Decreases in the extent of hSIPA were significantly less with use of heparin-coated circuits. There was an equivalent reduction in plasma vWF activity, in the two groups. Expression of platelet surface GP Ib decreased significantly during circulation and recovered after circulation. Reduction of surface GP Ib expression during circulation was significantly less in the C group than that in the N group. Decrease in surface GP Ib expression correlated (r = 0.88 in either group) with the magnitude of hSIPA, in the two groups. The progressive removal of surface GP Ib was mainly attributed to redistribution of GP Ib from the membrane skeleton into the cytoskeleton. Our observations suggest that use of heparin-coated circuits partly blocks the reduction of hSIPA, as a result of a lesser degree of redistribution of GP Ib.

50.1: Comparison of Numerical Methods for Analysis of Liquid Crystal Cell: In-Plane Switching

2003 ◽  
Vol 34 (1) ◽  
pp. 1378
Author(s):  
Hyung-Jin Yoon ◽  
Jun-Hee Lee ◽  
Min-Wan Choi ◽  
Jin-Woo Kim ◽  
Ohseob Kwon ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Numerical Methods ◽  
Liquid Crystal Cell ◽  
Crystal Cell

Hair density, wind speed, and heat loss in mammals

1965 ◽  
Vol 20 (4) ◽  
pp. 796-801 ◽  
Author(s):  
R. T. Tregear
Keyword(s):  
Wind Speed ◽  
Temperature Gradient ◽  
Heat Loss ◽  
Thermal Insulation ◽  
Hair Density ◽  
Wind Speeds

The heat loss from excised pelts of rabbits, horses, and pigs has been measured at various wind speeds. The temperature gradient through the fur was also measured. The thermal insulation of fur is highly dependent on the hair density (i.e., number of hairs/ cm2), and on the wind passing over its surface. If there are less than 1,000 hairs/cm2, an 8-mph wind penetrates deep into the fur, but at higher hair densities an 18-mph wind penetrates only a little way into the fur. fur insulation; obstruction of wind by hair Submitted on September 10, 1964

Measurement of surface shear stress vectors using liquid crystal coatings

AIAA Journal ◽  
1994 ◽  
Vol 32 (8) ◽  
pp. 1576-1582 ◽  
Author(s):  
Daniel C. Reda ◽  
Joseph J. Muratore
Keyword(s):  
Shear Stress ◽  
Liquid Crystal ◽  
Surface Shear Stress ◽  
Surface Shear

On the Critical Resolved Shear Stress and its Importance in the Fatigue Performance of Steels and other Metals with Different Crystallographic Structures

2022 ◽  
pp. 37-65
Author(s):  
M. Mlikota
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Fatigue Limit ◽  
High Fatigue ◽  
Steel Aisi ◽  
Crystallographic Structures ◽  
Face Centered ◽  
Set Up ◽  
Number Of Cycles ◽  
Critical Resolved Shear Stress

This study deals with the numerical estimation of the fatigue life represented in the form of strength-life (S-N, or Wöhler) curves of metals with different crystallographic structures, namely body-centered cubic (BCC) and face-centered cubic (FCC). Their life curves are determined by analyzing the initiation of a short crack under the influence of microstructure and subsequent growth of the long crack, respectively. Micro-models containing microstructures of the materials are set up by using the finite element method (FEM) and are applied in combination with the Tanaka-Mura (TM) equation in order to estimate the number of cycles required for the crack initiation. The long crack growth analysis is conducted using the Paris law. The study shows that the crystallographic structure is not the predominant factor that determines the shape and position of the fatigue life curve in the S-N diagram, but it is rather the material parameter known as the critical resolved shear stress (CRSS). Even though it is an FCC material, the investigated austenitic stainless steel AISI 304 shows an untypically high fatigue limit (208 MPa), which is higher than the fatigue limit of the BCC vanadium-based micro-alloyed forging steel AISI 1141 (152 MPa).

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