About the possibility of experimentally measuring an equilibrium contact angle and its theoretical and practical consequences

2006 ◽  
pp. 91-112
Keyword(s):  
Contact Angle ◽  
Equilibrium Contact Angle

Wettability Determination by Equilibrium Contact Angle Measurements: Reservoir Rock- Connate Water System With Injection of CO2

2012 ◽  
Author(s):  
Narjes Shojaikaveh ◽  
Cas Berentsen ◽  
Susanne Eva Johanne Rudolph-Floter ◽  
Karl Heinz Wolf ◽  
William Richard Rossen
Keyword(s):  
Contact Angle ◽  
Water System ◽  
Reservoir Rock ◽  
Equilibrium Contact Angle ◽  
Connate Water ◽  
Angle Measurements ◽  
Contact Angle Measurements

Nonlinear Dynamics of Gas-Liquid Separation in a Capillary Microseparator

2018 ◽  
Author(s):  
Anand N. P. Radhakrishnan ◽  
Marc Pradas ◽  
Serafim Kalliadasis ◽  
Asterios Gavriilidis
Keyword(s):  
Contact Angle ◽  
Phase Separation ◽  
Capillary Rise ◽  
Scaling Law ◽  
Critical Role ◽  
Contact Angles ◽  
Equilibrium Contact Angle ◽  
Liquid Slug ◽  
Liquid Separation ◽  
In Situ Investigation

Micro-engineered devices (MED) are seeing a significant growth in performing separation processes1. Such devices have been implemented in a range of applications from chemical catalytic reactors to product purification systems like microdistillation. One of the biggest advantages of these devices is the dominance of capillarity and interfacial tension forces. A field where MEDs have been used is in gas-liquid separations. These are encountered, for example, after a chemical reactor, where a gaseous component being produced needs immediate removal from the reactor, because it can affect subsequent reactions. The gaseous phase can be effectively removed using an MED with an array of microcapillaries. Phase-separation can then be brought about in a controlled manner along these capillary structures. For a device made from a hydrophilic material (e.g. Si or glass), the wetted phase (e.g. water) flows through the capillaries, while the non-wetted dispersed phase (e.g. gas) is prevented from entering the capillaries, due to capillary pressure. Separation of liquid-liquid flows can also be achieved via this approach. However, the underlying mechanism of phase separation is far from being fully understood. The pressure at which the gas phase enters the capillaries (gas-to-liquid breakthrough) can be estimated from the Young-Laplace equation, governed by the surface tension (γ) of the wetted phase, capillary width (d) and height (h), and the interface equilibrium contact angle (θeq). Similarly, the liquid-to-gas breakthrough pressure (i.e. the point at which complete liquid separation ceases and liquid exits through the gas outlet) can be estimated from the pressure drop across the capillaries via the Hagen-Poiseuille (HP) equation. Several groups reported deviations from these estimates and therefore, included various parameters to account for the deviations. These parameters usually account for (i) flow of wetted phase through ‘n’ capillaries in parallel, (ii) modification of geometric correction factor of Mortensen et al., 2005 2 and (iii) liquid slug length (LS) and number of capillaries (n) during separation. LS has either been measured upstream of the capillary zone or estimated from a scaling law proposed by Garstecki et al., 2006 3. However, this approach does not address the balance between the superficial inlet velocity and net outflow of liquid through each capillary (qc). Another shortcoming of these models has been the estimation of the apparent contact angle (θapp), which plays a critical role in predicting liquid-to-gas breakthrough. θapp is either assumed to be equal to θeq or measured with various techniques, e.g. through capillary rise or a static droplet on a flat substrate, which is significantly different from actual dynamic contact angles during separation. In other cases, the Cox-Voinov model has been used to calculate θapp from θeq and capillary number. Hence, the empirical models available in the literature do not predict realistic breakthrough pressures with sufficient accuracy. Therefore, a more detailed in situ investigation of the critical liquid slug properties during separation is necessary. Here we report advancements in the fundamental understanding of two-phase separation in a gas-liquid separation (GLS) device through a theoretical model developed based on critical events occurring at the gas-liquid interfaces during separation.

Derivation of the Equilibrium Contact Angle from the Parameters of a Small Drop Hanging on a Wire

1971 ◽  
pp. 134-139
Author(s):  
V. S. Baibakov ◽  
P. P. Ryazantsev ◽  
V. P. Safronov ◽  
L. M. Shcherbakov
Keyword(s):  
Contact Angle ◽  
Equilibrium Contact Angle ◽  
Small Drop

scholarly journals Applying Contact Angle to a Two-Dimensional Multiphase Smoothed Particle Hydrodynamics Model

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Amirsaman Farrokhpanah ◽  
Babak Samareh ◽  
Javad Mostaghimi
Keyword(s):  
Contact Angle ◽  
Triple Point ◽  
Smoothed Particle Hydrodynamics ◽  
Equilibrium Contact Angle ◽  
Shear Stresses ◽  
Contact Lines ◽  
Moving Contact ◽  
Moving Contact Lines ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

Equilibrium contact angle of liquid drops over horizontal surfaces has been modeled using smoothed particle hydrodynamics (SPH). The model is capable of accurate implementation of contact angles to stationary and moving contact lines. In this scheme, the desired value for stationary or dynamic contact angle is used to correct the profile near the triple point. This is achieved by correcting the surface normals near the contact line and also interpolating the drop profile into the boundaries. Simulations show that a close match to the chosen contact angle values can be achieved for both stationary and moving contact lines. This technique has proven to reduce the amount of nonphysical shear stresses near the triple point and to enhance the convergence characteristics of the solver.

Void Nucleation on a Contaminated Patch

1997 ◽  
Vol 12 (8) ◽  
pp. 2038-2042 ◽  
Author(s):  
B. M. Clemens ◽  
W. D. Nix ◽  
R. J. Gleixner
Keyword(s):  
Contact Angle ◽  
Simple Model ◽  
Integrated Circuit ◽  
Driving Force ◽  
Void Nucleation ◽  
Equilibrium Contact Angle ◽  
Simple Relationship ◽  
Nucleation Behavior ◽  
Strong Function ◽  
Nucleation Barrier

The energetics of a simple model of void nucleation on a contaminated patch between the sidewall and metal in an integrated circuit interconnect are examined to determine void nucleation behavior. The conditions under which there is no void nucleation barrier are represented by a simple relationship between the volume driving force, the equilibrium contact angle, the surface energy of the metal, and the contaminated patch radius. The void nucleation barrier, when it exists, is a strong function of these same parameters, and increases sharply as the driving force decreases, and under some conditions, increases with increasing equilibrium contact angle.

scholarly journals A spherical particle straddling a fluid/gas interface in an axisymmetric straining flow

1990 ◽  
Vol 217 ◽  
pp. 263-298 ◽  
Author(s):  
J. A. Stoos ◽  
L. G. Leal
Keyword(s):  
Contact Angle ◽  
Spherical Particle ◽  
Numerical Solutions ◽  
Contact Angles ◽  
Boundary Integral ◽  
Equilibrium Contact Angle ◽  
Equilibrium Configurations ◽  
Wide Range ◽  
The Stability ◽  
Neutrally Buoyant

Numerical solutions, obtained via the boundary-integral technique, are used to consider the effect of a linear axisymmetric straining flow on the existence of steady-state configurations in which a neutrally buoyant spherical particle straddles a gas–liquid interface. The problem is directly applicable to predictions of the stability of particle capture in flotation processes, and is also of interest in the context of contact angle and surface tension measurements. A primary goal of the present study is a determination of the critical capillary number, Cac, beyond which an initially captured particle is pulled from the interface by the flow, and the dependence of Cac on the equilibrium contact angle θc. We also present equilibrium configurations for a wide range of contact angles and subcritical capillary numbers.

Wettability Effects on Falling Film Flow and Heat Transfer Over Horizontal Tubes in Jet Flow Mode

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Avijit Karmakar ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Nusselt Number ◽  
Film Flow ◽  
Jet Flow ◽  
Equilibrium Contact Angle ◽  
Flow Mode ◽  
Falling Film ◽  
Tube Surface ◽  
Horizontal Tubes

Abstract The performance of a falling-film heat exchanger is strongly linked to the surface characteristics and the heat transfer processes that take place over the tubes. The primary aim of this numerical study is to characterize the influence of surface wettability on the film flow behavior and its associated surface heat transfer in the jet-flow mode. Volume of fluid (VOF) based simulations are carried out for horizontal tubes with different surface wettabilities. The wettability of the tube surfaces is represented using the Kistler's dynamic contact angle model. Surface wettability effects ranging from superhydrophilic to superhydrophobic are studied by varying the equilibrium contact angle from 2 deg to 175 deg. Two different liquid mass flow rates of 0.06 and 0.18 kg/m-s corresponding to the inline and staggered jet flow modes are studied. Results are presented in terms of the liquid film thickness, the contact areas between the different phases (solid–liquid and liquid–air), and the heat transfer coefficient or Nusselt number. The resistance imposed by the increasing contact angles inhibits the extent of the liquid spreading over the tube surface, and this, in turn, influences the liquid film thickness, and the wetted area of the tube surface. A significant decrement in the heat transfer rate from the tube surfaces was observed as the equilibrium contact angle increased from 2 deg to 175 deg. The local distributions of the Nusselt number over the tube surface are strongly influenced by the flow recirculation in the liquid bulk.

scholarly journals Experimental Study for Influence of Surfactants Chemical Microstructures on Wetting Effect about Coal Dust in Tongchuan Mining Area

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Youying Ma ◽  
Yuying Wang ◽  
Qingtao Zhang
Keyword(s):  
Contact Angle ◽  
Fatty Acid ◽  
Influencing Factors ◽  
Bituminous Coal ◽  
Coal Dust ◽  
Contact Angles ◽  
Shaanxi Province ◽  
Equilibrium Contact Angle ◽  
Resonance Spectroscopy ◽  
Wetting Ability

Because of the unsatisfactory dust suppression efficiency, coal dust still threatens production safety and personnel health. In order to understand the influence of the chemical microstructures of the surfactant on the wetting ability and to facilitate the rapid selecting of surfactants with good wetting performances for specific coal dust, fatty acid methyl ester ethoxylate (FMEE), dodecyl dimethyl betaine (BS-12), sodium fatty acid polyoxyethylene ether carboxylate (AEC), and dodecyl dimethyl benzyl ammonium chloride (DDBAC) were selected in this paper to study the wetting ability of these four surfactants on the bituminous coal dust in Tongchuan, Shaanxi province of China. First, the main functional groups and carbon composition of the coal dust and surfactants were determined by Fourier transform infrared spectroscopy and carbon-13 nuclear magnetic resonance spectroscopy experiments. Second, the drop shape analysis system DSA100 was used to measure the equilibrium contact angle of the surfactant solution with a concentration of 0.06% on bituminous coal dust. The relationship between the chemical microstructures of surfactants and contact angles was analyzed, and the main influencing factors were obtained. The results showed that the contact angle of DDBAC on coal sample dust was the smallest. In addition, the contents of hydroxyl, aromatic ring carbon, unprotonated carbon, and bridged aromatic carbon in surfactants had significant linear correlations with wettability, and the increase of their contents would lead to the decrease of contact angle. According to the results of correlation analysis and curve fitting, the evaluation model of influencing factors on the wettability to bituminous coal dust was established.

Sign in / Sign up

Export Citation Format

Share Document