Experimental investigation of a moving contact line in a channel

Émile, Janine; Sane, Arouna; Tabuteau, Hervé; Émile, Olivier

doi:10.1039/c3sm52115j

Cited by 6 publications

(4 citation statements)

References 45 publications

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“…Taylor [12] and Bretherton [13] performed two of the most classic investigations on the creeping motion of elongated confined bubbles in horizontal tubes of small diameters (millimeter scale). They found that the thickness of the liquid film wetting the channel walls increases with the capillary number following a power law [14]. Based on experimental data, Taylor [12] proposed 1=2 for the exponent of the empirical power law.…”

Section: Introductionmentioning

confidence: 99%

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Measurements and simulation of liquid films during drainage displacements and snap-off in constricted capillary tubes

Roman

Abu-Al-Saud

Tokunaga

et al. 2017

Journal of Colloid and Interface Science

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When a wetting liquid is displaced by air in a capillary tube, a wetting film develops between the tube wall and the air that is responsible for the snap-off mechanism of the gas phase. By dissolving a dye in the wetting phase it is possible to relate a measure of the absorbance in the capillary to the thickness of liquid films. These data could be used to compare with cutting edge numerical simulations of the dynamics of snap-off for which experimental and numerical data are lacking. Drainage experiments in constricted capillary tubes were performed where a dyed wetting liquid is displaced by air for varying flow rates. We developed an optical method to measure liquid film thicknesses that range from 3 to 1000μm. The optical measures are validated by comparison with both theory and direct numerical simulations. In a constricted capillary tube we observed, both experimentally and numerically, a phenomenon of snap-off coalescence events in the vicinity of the constriction that bring new insights into our understanding and modeling of two-phase flows. In addition, the good agreement between experiments and numerical simulations gives confidence to use the numerical method for more complex geometries in the future.

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Section: Introductionmentioning

confidence: 99%

“…Bretherton's law matched his experimental data for Ca ¼ 10 À3 À 10 À2 . Since the works of Taylor [12] and Bretherton [13], a number of studies have examined the thickness of the liquid film surrounding a bubble or a drop during steady motion [15][16][17][18][19][20][21]14,22,23].…”

Section: Introductionmentioning

confidence: 99%

Measurements and simulation of liquid films during drainage displacements and snap-off in constricted capillary tubes

Roman

Abu-Al-Saud

Tokunaga

et al. 2017

Journal of Colloid and Interface Science

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“…Earlier research efforts have examined contact line evolution for droplets deposited on non-swelling gels, 21,22 in which there is no mass exchange between the substrate and the droplets. In such instances, where surface deformations occur strictly due to the vertical component of the surface tension force, substrate deformation has a significant effect on contact line dynamics of the fluid motion.…”

Section: Introductionmentioning

confidence: 99%

Stick–slip water penetration into capillaries coated with swelling hydrogel

et al. 2015

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We have observed intriguing stick-slip behavior during capillary pressure driven filling of borosilicate microtubes coated with hydrogel on their inner wall. Swelling of hydrogel upon exposure to a translating waterfront is accompanied by ''stick-and-slip'' motion. This results in the macroscopic filling velocity for water penetration into glass capillaries coated with poly(N-isopropylacrylamide) (PNIPAM) being constant throughout the filling process, and reduced by three orders of magnitude when compared to filling of uncoated capillaries. A simple scaling analysis is used to introduce a possible explanation by considering the mechanisms responsible for pinning and unpinning of the contact line. The explanation assumes that the time scale for water diffusion into a hydrogel film and the resulting swelling/change of the local meniscus contact angle define the duration of each ''stick'' event. The ''slip'' length scale is in turn established by the elastocapillary deformation of dry hydrogel at the pinning point of the contact line. The sequential dynamics of these processes then determine the rate of water filling into a swelling capillary. Collectively, these experimental and theoretical results provide a new conceptual framework for liquid motion confined by soft, dynamically evolving polymer interfaces, in which the system creates an energy barrier to further motion through elasto-capillary deformation, and then lowers the barrier through diffusive softening. This insight has implications for optimal design of microfluidic and lab-on-achip devices based on stimuli-responsive smart polymers.

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“…Each petal must then be πd/600 = 1 mm wide. A Position Sensitive Detector (PSD) could measure optical beam shifts up to 1 nm [25]. It would then correspond to a rotation angle of φ = 10 −9 rad, and a displacement of the mirror of 10 −16 m here.…”

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confidence: 99%