scholarly journals The Effect of Patterned Micro-Structure on the Apparent Contact Angle and Three-Dimensional Contact Line

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 92
Author(s):  
Patrick Foltyn ◽  
Ferdinand Restle ◽  
Markus Wissmann ◽  
Stefan Hengsbach ◽  
Bernhard Weigand
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Quality Standard ◽  
Apparent Contact Angle ◽  
Angle Distribution ◽  
Phase Contact ◽  
Angle Variation ◽  
Structured Surfaces ◽  
Three Phase ◽  
Direct Laser

The measurement of the apparent contact angle on structured surfaces is much more difficult to obtain than on smooth surfaces because the pinning of liquid to the roughness has a tremendous influence on the three phase contact line. The results presented here clearly show an apparent contact angle variation along the three phase contact line. Accordingly, not only one value for the apparent contact angle can be provided, but a contact angle distribution or an interval has to be given to characterize the wetting behavior. For measuring the apparent contact angle distribution on regularly structured surfaces, namely micrometric pillars and grooves, an experimental approach is presented and the results are provided. A short introduction into the manufacturing process of such structured surfaces, which is a combination of Direct LASER Writing (DLW) lithography, electroforming and hot embossing shows the high quality standard of the used surfaces.

scholarly journals Dependency of Contact Angles on Three-Phase Contact Line: A Review

2021 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
H. Yildirim Erbil
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Contact Radius ◽  
Phase Contact ◽  
Sessile Droplet ◽  
Line Energy ◽  
Three Phase ◽  
Tension Term

The wetted area of a sessile droplet on a practical substrate is limited by the three-phase contact line and characterized by contact angle, contact radius and drop height. Although, contact angles of droplets have been studied for more than two hundred years, there are still some unanswered questions. In the last two decades, it was experimentally proven that the advancing and receding contact angles, and the contact angle hysteresis of rough and chemically heterogeneous surfaces, are determined by interactions of the liquid and the solid at the three-phase contact line alone, and the interfacial area within the contact perimeter is irrelevant. However, confusion and misunderstanding still exist in this field regarding the relationship between contact angle and surface roughness and chemical heterogeneity. An extensive review was published on the debate for the dependence of apparent contact angles on drop contact area or the three-phase contact line in 2014. Following this old review, several new articles were published on the same subject. This article presents a review of the novel articles (mostly published after 2014 to present) on the dependency of contact angles on the three-phase contact line, after a short summary is given for this long-lasting debate. Recently, some improvements have been made; for example, a relationship of the apparent contact angle with the properties of the three-phase line was obtained by replacing the solid–vapor interfacial tension term, γSV, with a string tension term containing the edge energy, γSLV, and curvature of the triple contact line, km, terms. In addition, a novel Gibbsian thermodynamics composite system was developed for a liquid drop resting on a heterogeneous multiphase and also on a homogeneous rough solid substrate at equilibrium conditions, and this approach led to the same conclusions given above. Moreover, some publications on the line energy concept along the three-phase contact line, and on the “modified” Cassie equations were also examined in this review.

The interaction of a moving fluid/fluid interface with a flat plate

1995 ◽  
Vol 296 ◽  
pp. 325-351 ◽  
Author(s):  
J. Billingham ◽  
A. C. King
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Flat Plate ◽  
Contact Line ◽  
Large Time ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Phase Contact ◽  
Three Phase ◽  
Time Problem

A well-known technique for metering a multiphase flow is to use small probes that utilize some measurement principle to detect the presence of different phases surrounding their tips. In almost all cases of relevance to the oil industry, the flow around such local probes is inviscid and driven by surface tension, with negligible gravitational effects. In order to study the features of the flow around a local probe when it meets a droplet, we analyse a model problem: the interaction of an infinite, initially straight, interface between two inviscid fluids, advected in an initially uniform flow towards a semi-infinite thin flat plate oriented at 90° to the interface. This has enabled us to gain some insight into the factors that control the motion of a contact line over a solid surface, for a range of physical parameter values.The potential flows in the two fluids are coupled nonlinearly at the interface, where surface tension is balanced by a pressure difference. In addition, a dynamic contact angle boundary condition is imposed at the three-phase contact line, which moves along the plate. In order to determine how the interface deforms in such a flow, we consider the small- and large-time asymptotic limits of the solution. The small-time and linearized large-time problems are solved analytically, using Mellin transforms, whilst the general large-time problem is solved numerically, using a boundary integral method.The form of the dynamic contact angle as a function of contact line velocity is the most important factor in determining how an interface deforms as it meets and moves over the plate. Depending on this, the three-phase contact line may, at one extreme, hang up on the leading edge of the plate or, at the other extreme, move rapidly along the surface of the plate. At large times, the solution asymptotes to an interface configuration where the contact line moves at the far-field velocity.

On the interpretation of contact angle for geomaterial wettability: Contact area versus three-phase contact line

2020 ◽  
Vol 195 ◽  
pp. 107579 ◽  
Author(s):  
Emad Sadeghinezhad ◽  
Mohammed Abdul Qadeer Siddiqui ◽  
Hamid Roshan ◽  
Klaus Regenauer-Lieb
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Contact Area ◽  
Phase Contact ◽  
Three Phase

Test of the stability of a three-phase contact line with negative line tension

1999 ◽  
Vol 96 (9) ◽  
pp. 1335-1339 ◽  
Author(s):  
ALAN E. VAN GIESSEN, DIRK JAN BUKMAN, B.
Keyword(s):  
Contact Line ◽  
Line Tension ◽  
Phase Contact ◽  
Three Phase ◽  
The Stability

Faster Nucleation of Ice and Carbon Dioxide Hydrates at the Three-Phase Contact Line

2021 ◽  
Author(s):  
Aritra Kar ◽  
Awan Bhati ◽  
Palash V. Acharya ◽  
Ashish Mhadeshwar ◽  
Roger Bonnecaze ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Contact Line ◽  
Phase Contact ◽  
Three Phase
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