scholarly journals Dynamic contact angle hysteresis in liquid bridges

2018 ◽  
Vol 555 ◽  
pp. 365-371 ◽  
Author(s):  
Zhang Shi ◽  
Yi Zhang ◽  
Mingchao Liu ◽  
Dorian A.H. Hanaor ◽  
Yixiang Gan
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Liquid Bridges

Simulation of Spreading Dynamics of a EWOD Droplet With Dynamic Contact Angle and Contact Angle Hysteresis

2009 ◽  
Author(s):  
Fangjun Hong ◽  
Ping Cheng ◽  
Zhen Sun ◽  
Huiying Wu
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Low Voltage ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Dielectric Surface ◽  
Contact Radius ◽  
Droplet Spreading ◽  
Spreading Dynamics

In this paper, the electrowetting dynamics of a droplet on a dielectric surface was investigated numerically by a mathematical model including dynamic contact angle and contact angle hysteresis. The fluid flow is described by laminar N-S equation, the free surface of the droplet is modeled by the Volume of Fluid (VOF) method, and the electrowetting force is incorporated by exerting an electrical force on the cells at the contact line. The Kilster’s model that can deal with both receding and advancing contact angle is adopted. Numerical results indicate that there is overshooting and oscillation of contact radius in droplet spreading process before it ceases the movement when the excitation voltage is high; while the overshooting is not observed for low voltage. The explanation for the contact line overshooting and some special characteristics of variation of contact radius with time were also conducted.

A Generalized Model for Dynamic Contact Angle

2017 ◽  
Author(s):  
Joseph J. Thalakkottor ◽  
Kamran Mohseni
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Force Balance ◽  
Surface Tension Gradient ◽  
Static Case ◽  
Dynamic Case ◽  
Microscopic Dynamic

Contact angle is an important parameter that characterizes the degree of wetting of a material. While for a static case, estimation and measurement of contact angle has been well established, same can not be said for the dynamic case. There is still a lack of understanding and consensus as to the fundamental factors governing the microscopic dynamic contact angle. With the aim of understanding the physics and identifying the parameters that govern the actual or microscopic dynamic contact angle, we derive a model based on first principles, by performing a force balance around the region containing the contact line. It is found that in addition to the surface tension, the microscopic dynamic contact angle is also a function of surface tension gradient and the jump in normal stress across the interface. In addition to having a significant contribution in determining the microscopic dynamic contact angle, surface tension gradient is also a key cause for contact angle hysteresis.

Moving contact lines on a two-dimensional rough surface

1985 ◽  
Vol 154 ◽  
pp. 1-28 ◽  
Author(s):  
Kalvis M. Jansons
Keyword(s):  
Contact Angle ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Contact Lines ◽  
Stick Slip ◽  
Moving Contact ◽  
Moving Contact Lines

The dynamic contact angle for a contact line moving over a solid surface with random sparse spots of roughness is determined theoretically in the limit of zero capillary number. The model exhibits many of the observed characteristics of moving contact lines on real rough surfaces, including contact-angle hysteresis and stick-slip. Several types of rough surface are considered, and a comparison is made between periodic and random rough surfaces.

Influence of surfactant transport suppression on dynamic contact angle hysteresis

2012 ◽  
Vol 291 (2) ◽  
pp. 361-366 ◽  
Author(s):  
Daniela Fell ◽  
Ngamjarassrivichai Pawanrat ◽  
Elmar Bonaccurso ◽  
Hans-Jürgen Butt ◽  
Günter K. Auernhammer
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Surfactant Transport

scholarly journals Dynamic Contact Angle and Corrosion Test Measurements on Cu and CuO-Stearic Acid Modifications on Steel Surfaces

2020 ◽  
Vol 2 (1) ◽  
pp. 49
Author(s):  
I Setiawan ◽  
S R Trisnanto ◽  
I O Suryani
Keyword(s):  
Contact Angle ◽  
Corrosion Rate ◽  
Stearic Acid ◽  
Corrosion Test ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Coated Steel ◽  
Sliding Angle ◽  
Bare Steel

In this study, a copper (Cu) coated steel surface’s dynamic con-tact angle and corrosion rate was compared to the bare steel and stearic acid modified surfaces. Various steps of surface treatment have been performed including electrodeposition of Cu, CuO formation from H2O2 immersion with stearic acid modi-fication to obtain dynamic contact angle and the corrosion rate data. The Cu-coated steel’s dynamic contact angle was increased as it implied the surface after Cu treatment was more hydro-philic than the bare steel, with sliding angle and contact angle hysteresis of 54.9o ± 2.39o and 39.5o ± 1.91o, respectively. How-ever, corrosion test measurements by using a mass loss method to quantify the corrosion rate showed that Cu-coated steel and stearic acid-modified Cu-O coated steel had no remarkable dif-ference in corrosion rate. It was found that the Cu-coated steel and stearic acid-modified Cu-O coated steel had corrosion rate eight times slower than the bare surface.

PREPARATION AND CHARACTERIZATIONS OF PTFE GRADIENT NANOSTRUCTURE ON SILK FABRIC

2007 ◽  
Vol 14 (04) ◽  
pp. 547-551 ◽  
Author(s):  
F. L. HUANG ◽  
Q. F. WEI ◽  
W. Z. XU ◽  
Q. LI
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Dynamic Contact Angle ◽  
Chemical Properties ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Attenuated Total Reflection ◽  
Silk Fabric ◽  
Water Contact ◽  
Sputter Coating

Superhydrophobic materials have been extensively studied because of their wonderful array of properties and applications. In this study, normal and superhydrophobic surface of silk fabric have been prepared via deposition of different shapes of PTFE nanostructure using magnetron sputter coating. The effects of PTFE sputter coating on surface morphology and surface chemical properties were characterized using atomic force microscopy (AFM) and ATR-FTIR (attenuated total reflection-Fourier transform infrared spectroscopy). The wettability of the fabric was characterized through measuring the surface contact angle by drop shape analysis apparatus and dynamic contact angle by Wilhelmy technique. As evaluated by water contact angle measurements, all the treatments resulted in a significant enhancement in the hydrophobicity of silk fabric, while larger sputtering pressures brought bigger PTFE nanoparticles, which led to higher contact angles. The results have also revealed that alternant working pressures, could bring gradient nanostructures which generated both high contact angle and less contact angle hysteresis.

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