Measurement of Surface Tension and Contact Angle by Analysis of Force Balance along a Bubble/Droplet Surface

2010 ◽  
Vol 36 (5) ◽  
pp. 441-448 ◽  
Author(s):  
Shuichi Iwata ◽  
Hironori Suzuki ◽  
Hideki Mori
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Droplet Surface ◽  
Force Balance

scholarly journals Prediction of Contact Angle of Nanofluids by Single-Phase Approaches

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4558 ◽  
Author(s):  
Nur Çobanoğlu ◽  
Ziya Haktan Karadeniz ◽  
Patrice Estellé ◽  
Raul Martínez-Cuenca ◽  
Matthias H. Buschmann
Keyword(s):  
Contact Angle ◽  
Single Phase ◽  
Substrate Surface ◽  
Droplet Surface ◽  
Force Balance ◽  
Radius Of Curvature ◽  
Geometrical Parameters ◽  
Ambient Conditions ◽  
Sessile Droplet ◽  
Droplet Shape

Wettability is the ability of the liquid to contact with the solid surface at the surrounding fluid and its degree is defined by contact angle (CA), which is calculated with balance between adhesive and cohesive forces on droplet surface. Thermophysical properties of the droplet, the forces acting on the droplet, atmosphere surrounding the droplet and the substrate surface are the main parameters affecting on CA. With nanofluids (NF), nanoparticle concentration and size and shape can modify the contact angle and thus wettability. This study investigates the validity of single-phase CA correlations for several nanofluids with different types of nanoparticles dispersed in water. Geometrical parameters of sessile droplet (height of the droplet, wetting radius and radius of curvature at the apex) are used in the tested correlations, which are based on force balance acting on the droplet surface, energy balance, spherical dome approach and empirical expression, respectively. It is shown that single-phase models can be expressed in terms of Bond number, the non-dimensional droplet volume and two geometrical similarity simplexes. It is demonstrated that they can be used successfully to predict CA of dilute nanofluids’ at ambient conditions. Besides evaluation of CA, droplet shape is also well predicted for all nanofluid samples with ±5% error.

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.

scholarly journals Dynamics of droplets under electrowetting effect with voltages exceeding the contact angle saturation threshold

2021 ◽  
Vol 925 ◽  
Author(s):  
Quoc Vo ◽  
Tuan Tran
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Applied Voltage ◽  
Droplet Surface ◽  
Capillary Waves ◽  
Force Balance ◽  
Equilibrium Contact Angle ◽  
Initial Contact ◽  
Viscous Effects ◽  
Electrowetting On Dielectric

Electrowetting on dielectric (EWOD) is a powerful tool in many droplet-manipulation applications with a notorious weakness caused by contact-angle saturation (CAS), a phenomenon limiting the equilibrium contact angle of an EWOD-actuated droplet at high applied voltage. In this paper, we study the spreading behaviours of droplets on EWOD substrates with the range of applied voltage exceeding the saturation limit. We experimentally find that at the initial stage of spreading, the driving force at the contact line still follows the Young–Lippmann law even if the applied voltage is higher than the CAS voltage. We then theoretically establish the relation between the initial contact-line velocity and the applied voltage using the force balance at the contact line. We also find that the amplitude of capillary waves on the droplet surface generated by the contact line's initial motion increases with the applied voltage. We provide a working framework utilising EWOD with voltages beyond CAS by characterising the capillary waves formed on the droplet surface and their self-similar behaviours. We finally propose a theoretical model of the wave profiles taking into account the viscous effects and verify this model experimentally. Our results provide avenues to utilise the EWOD effect with voltages beyond the CAS threshold, and have strong bearing on emerging applications such as digital microfluidic and ink-jet printing.

scholarly journals Role of Intermolecular Forces on the Contact Angle of Vegetable Oil Droplets during the Cooling Process

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Muhammad Akhlis Rizza ◽  
Widya Wijayanti ◽  
Nurkholis Hamidi ◽  
I. N. G. Wardana
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Hydrogen Bonds ◽  
Vegetable Oil ◽  
Intermolecular Forces ◽  
Contact Angles ◽  
Droplet Surface ◽  
Water Molecules ◽  
Oil Droplets

This study aims to experimentally determine the role of intermolecular forces on the contact angle of vegetable oil droplets. Contact angles were recorded using a microscope and measured using digital software. The results show that the surface tension of vegetable oils is influenced by the London force between the electron clouds of molecules. The process of cooling increases vegetable oil contact angles, due to the decreased kinetic energy of constituent molecules and increased London force on the molecules. A decrease in temperature causes the surrounding water vapor to condense, which adheres to the droplet surface (due to the hydrophilic properties of molecules). Hydrogen bonds develop after moisture adheres to the surface. Further, water molecules on the droplet surface reduce the surface tension, because of hydrogen bonds between the molecules on the droplet surface and moisture. Hydrogen bonds among the molecules force water molecules to accumulate on the droplet surface, which suppresses the droplet surface; therefore the contact angle decreases.

1604 Estimation of surface tension by analysis of force balance along droplet surface under oscillating field

2010 ◽  
Vol 2010 (0) ◽  
pp. 463-464
Author(s):  
Hironori SUZUKI ◽  
Shuichi IWATA ◽  
Hideki MORI
Keyword(s):  
Surface Tension ◽  
Droplet Surface ◽  
Force Balance

MOLECULAR DYNAMICS CALCULATIONS OF NEAR-CRITICAL LIQUID OXYGEN DROPLET SURFACE TENSION

2005 ◽  
Vol 15 (4) ◽  
pp. 413-422 ◽  
Author(s):  
Michael M. Micci ◽  
S. J. Lee ◽  
B. Vieille ◽  
C. Chauveau ◽  
Iskendar Gokalp
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Droplet Surface ◽  
Liquid Oxygen ◽  
Molecular Dynamics Calculations

scholarly journals Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

2021 ◽  
Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Moisture Content ◽  
Solid Wood ◽  
Contact Angles ◽  
Surface Moisture ◽  
Wood Coatings ◽  
The Relationship ◽  
Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

Increasing Storage Modulus, Contact Angle and Surface Tension of Airway Mucus Increases Clearance by Simulated Cough Through a Model Trachea

2010 ◽  
Author(s):  
Anpalaki J. Ragavan ◽  
Cahit A. Evrensel ◽  
Peter Krumpe
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Storage Modulus ◽  
Surface Properties ◽  
Respiratory Diseases ◽  
Interactive Effects ◽  
Altered Surface ◽  
Human Trachea ◽  
Tension Increase ◽  
And Storage

Altered surface and viscoelastic material properties of mucus during respiratory diseases have a strong influence on its clearance by cilia and cough. Combined effects of the surface properties (contact angle and surface tension) and storage modulus with relatively unchanged viscosity on displacement of the simulated mucus aliquot during simulated cough through a model adult human trachea is investigated. For the mucus simulants used in this study contact angle and surface tension increase significantly as storage modulus increase while viscosity remains practically unchanged. Displacement of mucus simulant aliquots increased significantly with increasing storage modulus (and contact angle) at a given cough velocity in the range between 5 meters/second (m/s) and 30 m/s with duration 0.3 s. Results suggest that the interactive effects of elasticity and surface properties may help facilitate mucus displacement at low cough velocities.

scholarly journals Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Gang Zhou ◽  
Han Qiu ◽  
Qi Zhang ◽  
Mao Xu ◽  
Jiayuan Wang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Specific Surface ◽  
Coal Dust ◽  
Single Point ◽  
Contact Angles ◽  
Critical Surface ◽  
Volume Percentage ◽  
Surface Areas ◽  
Specific Surface Areas

Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

Sign in / Sign up

Export Citation Format

Share Document