Simulated Contact Angle Hysteresis of a Three-Dimensional Drop on a Chemically Heterogeneous Surface: A Numerical Example

Brandon, Simon; Wachs, Amir; Marmur, Abraham

doi:10.1006/jcis.1997.4912

Cited by 56 publications

(58 citation statements)

References 13 publications

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“…The later seem to be inherited from the observed evolution of both CA and CD. Such behavior of the triple contact has been observed since long, especially in the evolution CA but also in CD of evaporating sessile drops [35,36].…”

Section: Instabilitiesmentioning

confidence: 75%

Laplace pressure evolution and four instabilities in evaporating two-grain liquid bridges

2015

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Dynamic variables characterizing evolution during evaporation of capillary bridge between two spheres are analyzed. The variables include: average Laplace pressure, pressure resulting force, surface tension force and total capillary force calculated based on the previously reported geometrical variables using Young-Laplace law [1,2]. This is the first time to our knowledge that Laplace pressure is calculated from the measured bridge curvatures along the process of evaporation and compared to experimental measurement data. A comparison with the experimental data from analogous capillary bridge extension tests is also shown and discussed. The behavior of evaporating liquid bridges is seen as strongly dependent on the grain separation. Initial negative Laplace pressure at small separations is seen to significantly augment during an advanced stage of evaporation, but to turn into positive pressure, after an instability toward the end of the process, and prior to rupture. At larger separations the pressure is positive all the time, changing a little, but rupturing early. Rupture in all cases occurs at positive pressure. However, because of the evolution of the surface area of contact, the resultant total capillary forces are always tensile, and decreasing toward zero in all cases. Comparison between measured total resultant capillary forces and those calculated from the Young-Laplace law is very good, except for some discrepancies at very small separations (below 50 μm). Up to four consecutive instabilities of capillary bridge are seen developing at some sphere separations. They are: re-pinning-induced suction (pressure) instability; Rayleigh nodoid/ catenoid/unduloid unstable transition, associated with zero-pressure; Rayleigh unduloid/cylinder unstable transition, associated with the formation of a liquid-wire; and lastly, a pinching instability of the liquid-wire, associated with the bridge rupture. Rupture of the bridges is seen at large separations to occur quite early, at only 1/4-1/3 of the initial water volume evaporated. At smallest separations, rupture occurs in a seemingly unstable way when water evaporates from the bridge thinnest section of the neck.

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Section: Instabilitiesmentioning

confidence: 75%

Laplace pressure evolution and four instabilities in evaporating two-grain liquid bridges

2015

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“…1). A similar investigation of drop shapes on chemically heterogeneous surfaces has been reported earlier by Brandon et al [16,17]. We neglect gravity, which is a reasonable assumption for small drops.…”

Section: Numerical Simulation Of the Drop Shapementioning

confidence: 76%

Anisotropy in the wetting of rough surfaces

Chen

Lee

et al. 2005

Journal of Colloid and Interface Science

312

266

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“…Brandon et al [24] used Surface Evolver to simulate a sessile drop onto a chemically patterned surface. The model implied a flat substrate with a surface tension evolving as a sinusoidal function along a single direction.…”

Section: Surface Evolver Softwarementioning

confidence: 99%

Wetting of anisotropic sinusoidal surfaces—experimental and numerical study of directional spreading

Fischer¹,

Bigerelle²,

Kubiak³

et al. 2014

Surf. Topogr.: Metrol. Prop.

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Directional wettability, i.e. variation of wetting properties depending on the surface orientation, can be achieved by anisotropic surface texturing. A new high precision process can produce homogeneous sinusoidal surfaces (in particular parallel grooves) at the microscale, with a nano-scale residual roughness five orders of magnitude smaller than the texture features. Static wetting experiments have shown that this pattern, even with a very small aspect ratio, can induce a strong variation of contact angle depending on the direction of observation. A comparison with numerical simulations (using Surface Evolver software) shows good agreement and could be used to predict the fluid-solid interaction and droplet behaviour on textured surfaces. Two primary mechanisms of directional spreading of water droplets on textured stainless steel surface have been identified. The first one is the mechanical barrier created by the textured surface peaks, this limits spreading in perpendicular direction to the surface anisotropy. The second one is the capillary action inside the sinusoidal grooves accelerating spreading along the grooves. Spreading has been shown to depend strongly on the history of wetting and internal drop dynamics.

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Simulated Contact Angle Hysteresis of a Three-Dimensional Drop on a Chemically Heterogeneous Surface: A Numerical Example

Cited by 56 publications

References 13 publications

Laplace pressure evolution and four instabilities in evaporating two-grain liquid bridges

Laplace pressure evolution and four instabilities in evaporating two-grain liquid bridges

Anisotropy in the wetting of rough surfaces

Wetting of anisotropic sinusoidal surfaces—experimental and numerical study of directional spreading

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