Transient flow-driven distortion of a nematic liquid crystal in channel flow with dissipative weak planar anchoring

Cousins, Joseph R. L.; Wilson, S. K.; Mottram, Nigel J.; Wilkes, David; Weegels, Leo

doi:10.1103/physreve.102.062703

Cited by 6 publications

(3 citation statements)

References 47 publications

(106 reference statements)

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“…The range of anisotropic wetting and dewetting phenomena occurring in this nematic system may also be useful from a technological perspective; for instance, for tailored dewetting of liquid films, as discussed in §1 [2,6,19,44,45]. The variety of possible transitions between twodimensional equilibrium states will have similar forms in three dimensions, which may be relevant to applications such as the one-drop-filling method of LCD manufacturing [66][67][68] and…”

Section: Discussionmentioning

confidence: 99%

Young and Young–Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

et al. 2022

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Motivated by the need for greater understanding of systems that involve interfaces between a nematic liquid crystal, a solid substrate and a passive gas that include nematic–substrate–gas three-phase contact lines, we analyse a two-dimensional static ridge of nematic resting on a solid substrate in an atmosphere of passive gas. Specifically, we obtain the first complete theoretical description for this system, including nematic Young and Young–Laplace equations, and then, making the assumption that anchoring breaking occurs in regions adjacent to the contact lines, we use the nematic Young equations to determine the continuous and discontinuous transitions that occur between the equilibrium states of complete wetting, partial wetting and complete dewetting. In particular, in addition to continuous transitions analogous to those that occur in the classical case of an isotropic liquid, we find a variety of discontinuous transitions, as well as contact-angle hysteresis, and regions of parameter space in which there exist multiple partial wetting states that do not occur in the classical case.

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Section: Discussionmentioning

confidence: 99%

Young and Young–Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

et al. 2022

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“…The range of anisotropic wetting and dewetting phenomena occurring in this nematic system may also be useful from a technological perspective, for instance, for tailored dewetting of liquid films, as discussed in Section 1 [2,6,18,41,42]. The variety of possible transitions between two-dimensional equilibrium states will have similar forms in three dimensions, which may be relevant to applications such as the One Drop Filling method of LCD manufacturing [64][65][66] and adaptive-lens technologies [4,5]. In order to explore such applications, further theoretical investigations, particularly into the dynamics of transitions, and experimental investigations would be needed.…”

Section: Discussionmentioning

confidence: 99%

Young and Young--Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

Cousins,

Duffy,

Wilson

et al. 2021

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Motivated by the need for greater understanding of systems that involve interfaces between a nematic liquid crystal, a solid substrate, and a passive gas that includes nematic-substrate-gas three-phase contact lines, we analyse a two-dimensional static ridge of nematic resting on a solid substrate in an atmosphere of passive gas. Specifically, we obtain the first complete theoretical description for this system, including nematic Young and Young-Laplace equations, and then, under the assumption that anchoring breaking occurs in regions adjacent to the contact lines, we use the nematic Young equations to determine the continuous and discontinuous transitions that occur between the equilibrium states of complete wetting, partial wetting, and complete dewetting.In particular, in addition to continuous transitions analogous to those that occur in the classical case of an isotropic liquid, we find a variety of discontinuous transitions, as well as contact-angle hysteresis, and regions of parameter space in which there exist multiple partial wetting states that do not occur in the classical case.

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“…In the present work we assume that gravitational effects can be neglected compared to surface-tension effects, and therefore we require that the semi-width of the ridge d is much smaller than the capillary length l = (γ GN /(ρg)) 1/2 , where ρ is the constant density of the nematic and g is the magnitude of acceleration due to gravity [52]. This assumption is appropriate for the physical experiments presented in Section VI, where l = 2 × 10 −3 m and d = 6 × 10 −4 m, and for many other applications, including ridges of discotic liquid crystals used in new semi-conductor applications [12], nematic diffraction gratings [13,14], ridges of nematic mixtures [32], and possibly for nematic droplets used in LCD manufacturing [53,54].…”

Section: B Governing Equations For a Pinned Nematic Ridgementioning

confidence: 99%

Weak-anchoring effects in a thin pinned ridge of nematic liquid crystal

et al. 2023

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A theoretical investigation of weak-anchoring effects in a thin two-dimensional pinned static ridge of nematic liquid crystal resting on a flat solid substrate in an atmosphere of passive gas is performed. Specifically, we solve a reduced version of the general system of governing equations recently derived by Cousins et al. [Proc. Roy. Soc. A, 478(2259):20210849, 2022] valid for a symmetric thin ridge under the one-constant approximation of the Frank-Oseen bulk elastic energy with pinned contact lines to determine the shape of the ridge and the behaviour of the director within it. Numerical investigations covering a wide range of parameter values indicate that the energetically-preferred solutions can be classified in terms of the Jenkins-Barratt-Barbero-Barberi critical thickness into five qualitatively different types of solution. In particular, the theoretical results suggest that anchoring breaking occurs close to the contact lines. The theoretical predictions are supported by the results of physical experiments for a ridge of the nematic 4'-pentyl-4-biphenylcarbonitrile (5CB). In particular, these experiments show that the homeotropic anchoring at the gas-nematic interface is broken close to the contact lines by the stronger rubbed planar anchoring at the nematic-substrate interface. A comparison between the experimental values of and the theoretical predictions for the effective refractive index of the ridge gives a first estimate of the anchoring strength of an interface between air and 5CB to be (9.80 ± 1.12) × 10 −6 Nm −1 at a temperature of (22 ± 1.5) • C.

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Transient flow-driven distortion of a nematic liquid crystal in channel flow with dissipative weak planar anchoring

Cited by 6 publications

References 47 publications

Young and Young–Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

Young and Young–Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

Young and Young--Laplace equations for a static ridge of nematic liquid crystal, and transitions between equilibrium states

Weak-anchoring effects in a thin pinned ridge of nematic liquid crystal

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