Contact-Angle Hysteresis Caused by a Random Distribution of Weak Heterogeneities on a Solid Surface

Öpik, U.

doi:10.1006/jcis.1999.6637

Cited by 15 publications

(12 citation statements)

References 19 publications

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“…Subsequently, models of surfaces with randomly distributed defects invoked pinning of the three-phase contact line to study CAH [18,19]. Further, explicit consideration of the three-phase contact line pinning due to defects allowed random distribution of defects to be studied in a statistical manner [20]. A thermodynamic model combining surface roughness and heterogeneities has also been proposed [21].…”

Section: Introductionmentioning

confidence: 99%

Constitutive modeling of contact angle hysteresis

Vedantam

Panchagnula

2008

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Constitutive modeling of contact angle hysteresis

Vedantam

Panchagnula

2008

Journal of Colloid and Interface Science

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“…Many theoretical works have been performed to explain and to analyze the situation [7][8][9][10][11][12][13][14][15][16][17][18], exploring the presence of different causes of hysteresis.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Procedure to Obtain the Equilibrium Contact Angle from the Wilhelmy Method

Volpe¹,

Maniglio

Siboni

et al. 2001

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Une méthode expérimentale pour mesurer l'angle de contact d'équilibre avec la technique de Wilhelmy -La théorie des angles de contact a été développée en utilisant le concept d'angle de Young, une relation d'équilibre établie pour des surfaces complètement lisses et homogènes ; sur surfaces réelles, on considère habituellement que l'on peut obtenir des états « métastables » d'équilibre dans lesquels la forme du ménisque le long de la ligne à trois phases n'est pas complètement équivalente à celle du ménisque d'équilibre. Dans cet article, nous présentons une nouvelle méthode d'obtention de l'angle de contact d'équilibre par une simple modification de la microbalance de Wilhelmy. L'apport d'énergie acoustique au liquide à une fréquence capable de provoquer la formation résonante d'ondes capillaires, suivi par la réduction de l'amplitude de la vibration, permet au ménisque de bouger et de passer de sa forme métastable, d'avancée ou de recul, à celle d'équilibre stable. Ce résultat paraît être essentiellement indépendant des conditions initiales ; il a été possible de confirmer la théorie selon laquelle les barrières d'énergie entre états métastables loin de l'équilibre sont plus faibles que celles à l'équilibre. L'équation qui met en relation le cosinus de l'angle de contact d'équilibre et la moyenne arithmétique des cosinus des angles d'avancée et de recul a été confirmée pour des surfaces homogènes, mais elle a été réfutée dans le cas de surfaces macroscopiquement hétérogènes. Cette méthode paraît par ailleurs prometteuse par sa simplicité et son faible coût.

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“…are average velocities and front positions. We can ensure that h 1 ≺ h 2 initially by a suitable periodic translation which does not affect the long time average (41). Since h 1 ≺ h 2 for all time, it follows that for large T ,…”

Section: The Homogenized Front Velocitymentioning

confidence: 99%

“…These laws have known limits of applicability, however ([4, Chapter 9], [3]). More recent studies have considered this problem from the point of view of mechanics [4,34], statistics [14,41], and gamma convergence techniques [1].In the dynamic case, much less is understood. Flows over heterogeneous surfaces have been studied experimentally [11,12,38,39,47] and computationally [49,50].…”

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confidence: 99%

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Homogenization of contact line dynamics

Glasner¹

2006

Interfaces Free Bound.

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This paper considers the effects of substrate inhomogeneity on the motion of the three phase contact line. The model employed assumes the slowness of the contact line in comparison to capillary relaxation. The homogenization of this free boundary problem with a spatially periodic velocity law is considered. Formal multiple scales analysis yields a local, periodic problem whose time-averaged dynamics corresponds to the homogenized front velocity. A rigorous understanding of the long time dynamics is developed using comparison techniques. Computations employing boundary integral equations are used to illustrate the consequences of the analysis. Advancing and receding contact angles, pinning and anisotropic motion can be predicted within this framework.In many realistic circumstances, the static and dynamic wetting properties of liquids are substantially influenced by imperfections in the solid surface. Heterogeneities result in contact lines with a fine scale structure that may lead to pinning of the evolving front and hysteresis of the overall fluid shape.Understanding the role that surface imperfections play is part of larger theoretical effort to determine the macroscopic manifestations of microscopic contact line features [4,15,42]. Classical fluid mechanics is by itself insufficient to describe the moving contact line [32], and the additional physical ingredients needed are still controversial. Modeling and theoretical studies include notions of slip boundary conditions [28,30], continuum models [15,45,51], rheological modifications [27,53], and atomistic simulations [19,29] (see [4,42] for more extensive accounts). There is also considerable technological importance in understanding the role of wetting on patterned substrates [11,17,37,48].The model studied here is based on the slowness of the contact line in comparison to the time for capillary relaxation, known as the quasistatic limit. This represents possibly the simplest nontrivial global model for contact line motion, and therefore provides a good point of departure for examining surface heterogeneity. In this limiting case, the fluid pressure is constant, and the fluid's geometry can therefore be described as a "capillary" surface. Motion arises from an imbalance of surface forces at the contact line itself, which can be modeled by a constitutive velocity-contact angle law. This approximation has been utilized in many previous studies [2, 21-23, 28, 31, 33, 40, 43].The static effects of surface heterogeneity have been studied for some time. Early heuristic theories considered the averaged effect of rough surfaces and chemical heterogeneities on the equilibrium contact angle [7,54]. These laws have known limits of applicability, however ([4, Chapter 9], [3]). More recent studies have considered this problem from the point of view of mechanics [4,34], statistics [14,41], and gamma convergence techniques [1].In the dynamic case, much less is understood. Flows over heterogeneous surfaces have been studied experimentally [11,12,38,39,47] and computationall...

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Contact-Angle Hysteresis Caused by a Random Distribution of Weak Heterogeneities on a Solid Surface

Cited by 15 publications

References 19 publications

Constitutive modeling of contact angle hysteresis

Constitutive modeling of contact angle hysteresis

An Experimental Procedure to Obtain the Equilibrium Contact Angle from the Wilhelmy Method

Homogenization of contact line dynamics

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