Dynamic contact angles

Gutoff, Edgar B.; Kendrick, Chito

doi:10.1002/aic.690280314

Cited by 119 publications

(62 citation statements)

References 13 publications

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“…The above observation are clearly expressed in the air entrainment speeds data shown in Figures 5-8 for the 4 sides tested together with the correlation of Gutoff and Kendrick (1982). The smooth sides gave air entrainment speeds close to those obtained by Gutoff and Kendrick and this confirms the accuracy of the experimental technique.…”

Section: When We Carried Out the Experiments With The Two Polyester Ssupporting

confidence: 72%

The effect of substrate roughness on air entrainment in dip coating

Benkreira

2004

Chemical Engineering Science

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Dynamic wetting failure was observed in the simple dip coating flow with a series of substrates, which had a rough side and a comparatively smoother side. When we compared the air entrainment speeds on both sides, we found a switch in behaviour at a critical viscosity. At viscosity lower than a critical value, the rough side entrained air at lower speeds than the smooth side. Above the critical viscosity the reverse was observed, the smooth side entraining air at lower speed than the rough side. Only substrates with significant roughness showed this behaviour. Below a critical roughness, the rough side always entrained air at lower speeds than the smooth side. These results have both fundamental and practical merits. They support the hydrodynamic theory of dynamic wetting failure and imply that one can coat viscous fluids at higher speeds than normal by roughening substrates. A mechanism and a model are presented to explain dynamic wetting failure on rough surfaces.

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Section: When We Carried Out the Experiments With The Two Polyester Ssupporting

confidence: 72%

The effect of substrate roughness on air entrainment in dip coating

Benkreira

2004

Chemical Engineering Science

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“…Very fine bubbles air entrainment is observed most typically in the plunging tape flow, where above a critical speed, V* plunging , the dynamic wetting line changes from a straight line into a vvv-shaped line with tiny air bubbles detaching from the tips of the v-segments. This is now a classical observation reported first by Deryagin & Levi (1964) and later by many researchers including Burley & Kennedy (1976), Blake & Ruschak (1979), Gutoff & Kendrick (1982) and Cohu & Benkreira (1998). The data all show that for smooth substrates and zero wetting angle 1 Gutoff & Kendrick (1987) and Lee & Liu (1990) found similar air entrainment type and speeds in slide and slot coating respectively.…”

Section: Introductionsupporting

confidence: 62%

Dynamic wetting in metering and pre-metered forward roll coating

Benkreira

2002

Chemical Engineering Science

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“…The characteristic temperature drop is chosen equal to T * = 10 0 C. We perform the calculations with different values of the coefficients γ, γ 0 of friction type "liquid -solid wall" [8,24] and for two different values of static contact angle Φ 0 (Φ 0 = 63 and Φ 0 = 87 degrees). The calculations are carried out in the case of equal values of the coefficients γ and γ 0 (γ = γ 0 = 100 and γ = γ 0 = 1) under conditions of normal (g = 981 cm/s 2 ) and low gravity (g = 9.81 cm/s 2 ).…”

Section: Numerical Resultsmentioning

confidence: 99%

Numerical Investigation of a Dependence of the Dynamic Contact Angle on the Contact Point Velocity in a Problem of the Convective Fluid Flow

Goncharova¹,

Zakurdaeva²

2016

J. Sib. Fed. Univ., Math. phys.

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A two-dimensional problem of the fluid flows with a dynamic contact angle is studied in the case of an uniformly moving contact point. Mathematical modeling of the flows is carried out with the help of the Oberbeck-Boussinesq approximation of the Navier-Stokes equations. On the thermocapillary free boundary the kinematic, dynamic conditions and the heat exchange condition of third order are fulfilled. The slip conditions (conditions of proportionality of the tangential stresses to the difference of the tangential velocities of liquid and wall) are prescribed on the solid boundaries of the channel supporting by constant temperature. The dependence of the dynamic contact angle on the contact point velocity is investigated DOI: 10.17516/1997DOI: 10.17516/ -1397DOI: 10.17516/ -2016. IntroductionThe problems of flows of a viscous incompressible fluid in the domains with interfaces are very important for investigations. The features of the fluid flows in the domains with free boundaries and interfaces are the subject of many investigations in the last decade. Such interest is explained by need of study some phenomena in the flow structure, which arise due to the effects related with the gas phase and solid wall properties. One of the most important questions of mathematical modeling of the convective fluid flows in a domain with an interface is a correct formulation of the boundary conditions. From the mathematical point of view the non-stationary fluid flows with free boundaries remain to be very difficult for investigations because of the dynamic contact angle problem [1][2][3][4][5][6]. The problem of dynamic contact angle occurs due to the incompatibility of the conditions on the free surface of the liquid and the conditions of adhesion on a solid surface * gon@math.asu.ru c ⃝ Siberian Federal University. All rights reserved -296 - in vicinity of the moving three-phase contact line. There are various methods of statement of the problems with contact angles, describing a motion of a viscous incompressible liquid in the presence of a moving contact line (or contact point in the two-dimensional case). These problem statements assume a replacement of the no-slip conditions terms by the slip conditions on some sections of the solid walls near the contact line, the asymptotic approach, the assumption of the contact angle equality to π or to "zero" etc. (see, for example, [1,2,7,8]). For some mathematical models of fluid flows with dynamic contact angle the correctness of the initial boundary-value problems has been proved [1,2,7,[9][10][11].The problem of the fluid flows in a two dimensional domain will be studied in the case when the contact points are moving with a constant velocity. A behavior of the contact angle depends on the velocity of movement of the contact point, on the nature of the boundary thermal conditions specified on solid walls and free thermocapillary boundary, on the values of the friction coefficients and also on intensity of the gravitation field. We consider the Oberbeck-Boussinesq equations of c...

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Dynamic contact angles

Cited by 119 publications

References 13 publications

The effect of substrate roughness on air entrainment in dip coating

The effect of substrate roughness on air entrainment in dip coating

Dynamic wetting in metering and pre-metered forward roll coating

Numerical Investigation of a Dependence of the Dynamic Contact Angle on the Contact Point Velocity in a Problem of the Convective Fluid Flow

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