scholarly journals Variation of Contact Angles in Brine/CO2/Mica System considering Short-Term Geological CO2 Sequestration Condition

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Mohammad Jafari ◽  
Jongwon Jung
Keyword(s):  
Contact Angle ◽  
Triple Line ◽  
Contact Angles ◽  
Storage Site ◽  
Short Term ◽  
Two Phase ◽  
Uncertainty In Measurement ◽  
Wide Range ◽  
Geological Co2 Sequestration ◽  
Term Performance

Geological CO2 sequestration has been proposed as an effective solution to mitigate excessive human-emitted CO2 in atmosphere. Knowledge of immiscible two-phase flow of CO2-water/brine is necessary to evaluate the efficiency and safety of geological storage sites. Among forces dominating fluid flow, capillary pressure is highly important because of high uncertainty in measurement due to ambiguous wettability behavior of geomaterials. In particular, time-dependent wettability of geomaterials is of interest for predicting short-term performance of the storage site. After injection of CO2 into an aquifer, both the CO2 and water/brine in rocks pores are unsaturated and tend to dissolve into each other. Present study investigates the variation of contact angle on mica sheet using a captive bubble method at a wide range of pressures and salinities under unsaturated condition. Our results showed a general increase of contact angle with time. Comparison of unsaturated contact angle with previous results in the literature showed a wide span of wettability behavior, ranging from receding to advancing contact angle values reported in the literature. The observed decrease in wettability by time due to heterogeneity and pinning effect of triple line can jeopardize the safety of geological carbon sequestration projects in short-term after injection of CO2.

Surface Wettability Effects in Heat and Fluid Flow

2006 ◽  
Author(s):  
Yasuyuki Takata
Keyword(s):  
Heat Flux ◽  
Contact Angle ◽  
Two Phase Flow ◽  
Contact Angles ◽  
Bubble Nucleation ◽  
Surface Wettability ◽  
Water Repellent ◽  
Phase Flow ◽  
Two Phase ◽  
Wide Range

Effects of surface wettability on liquid-vapor phase change phenomena and single- and two-phase flow in tube have been studied in wide range of contact angles using superhy drophilic (SH) and super-water-repellent (SWR) surfaces. Heat transfer in falling film evaporation on a TiO2-coated SH surface is tremendously enhanced due to very thin stable film. In pool bioling, critical heat flux (CHF) and minimum heat flux (MHF) increase with the decrease in contact angle. Wetting limit temperature of water drop on heated surface increases with the decrease in contact angle. In pool boiling on SWR surface, bubble nucleation and film boiling occur in extremely small superheating. Drag reduction was observed in water flow in tube with SWR coating in laminar flow region, and on the other hand, in two-phase flow pressure drop for the SH wall is smaller than that for the SWR wall.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

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.

scholarly journals Amphiphobic Nanostructured Coatings for Industrial Applications

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 787 ◽  
Author(s):  
Federico Veronesi ◽  
Giulio Boveri ◽  
Mariarosa Raimondo
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Friction Reduction ◽  
Hybrid Coatings ◽  
Wetting Behavior ◽  
Wide Range ◽  
Solid Liquid

The search for surfaces with non-wetting behavior towards water and low-surface tension liquids affects a wide range of industries. Surface wetting is regulated by morphological and chemical features interacting with liquid phases under different ambient conditions. Most of the approaches to the fabrication of liquid-repellent surfaces are inspired by living organisms and require the fabrication of hierarchically organized structures, coupled with low surface energy chemical composition. This paper deals with the design of amphiphobic metals (AM) and alloys by deposition of nano-oxides suspensions in alcoholic or aqueous media, coupled with perfluorinated compounds and optional infused lubricant liquids resulting in, respectively, solid–liquid–air and solid–liquid–liquid working interfaces. Nanostructured organic/inorganic hybrid coatings with contact angles against water above 170°, contact angle with n-hexadecane (surface tension γ = 27 mN/m at 20 °C) in the 140–150° range and contact angle hysteresis lower than 5° have been produced. A full characterization of surface chemistry has been undertaken by X-ray photoelectron spectroscopy (XPS) analyses, while field-emission scanning electron microscope (FE-SEM) observations allowed the estimation of coatings thicknesses (300–400 nm) and their morphological features. The durability of fabricated amphiphobic surfaces was also assessed with a wide range of tests that showed their remarkable resistance to chemically aggressive environments, mechanical stresses and ultraviolet (UV) radiation. Moreover, this work analyzes the behavior of amphiphobic surfaces in terms of anti-soiling, snow-repellent and friction-reduction properties—all originated from their non-wetting behavior. The achieved results make AM materials viable solutions to be applied in different sectors answering several and pressing technical needs.

Tailoring Surface Hydrophobicity of Commercial Polyimide by Laser-Induced Nanocarbon Texturing

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Moataz Abdulhafez ◽  
Angela J. McComb ◽  
Mostafa Bedewy
Keyword(s):  
Contact Angle ◽  
Surface Characterization ◽  
Surface Engineering ◽  
Processing Parameters ◽  
Surface Hydrophobicity ◽  
Spot Size ◽  
Contact Angles ◽  
Water Contact ◽  
Wide Range ◽  
Surface Nanostructure

Abstract The growth of laser-induced nanocarbons, referred to here as laser-induced nanocarbon (LINC) for short, directly on polymeric surfaces is a promising route toward surface engineering of commercial polymers. This paper aims to demonstrate how this new approach can enable achieving varied surface properties based on tuning the nanostructured morphology of the formed graphitic material on commercial polyimide (Kapton) films. We elucidate the effects of tuning laser processing parameters on the achieved nanoscale morphology and the resulting surface hydrophobicity or hydrophilicity. Our results show that by varying lasing power, rastering speed, laser spot size, and line-to-line gap sizes, a wide range of water contact angles are possible, i.e., from below 20 deg to above 110 deg. Combining water contact angle measurements from an optical tensiometer with LINC surface characterization using optical microscopy, electron microscopy, and Raman spectroscopy enables building the process–structur–property relationship. Our findings reveal that both the value of contact angle and the anisotropic wetting behavior of LINC on polyimide are dependent on their hierarchical surface nanostructure which ranges from isotropic nanoporous morphology to fibrous morphology. Results also show that increasing gap sizes lead to an increase in contact angles and thus an increase in the hydrophobicity of the surface. Hence, our work highlight the potential of this approach for manufacturing flexible devices with tailored surfaces.

Wetting and Interfacial Behavior of Molten Al on Mo-Ni(Co)-Si Coated SiC Ceramic

2016 ◽  
Vol 697 ◽  
pp. 481-484 ◽  
Author(s):  
San Tuan Zhao ◽  
Xiang Zhao Zhang ◽  
Gui Wu Liu ◽  
Hong Yan Xia ◽  
Zhong Qi Shi ◽  
...  
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Triple Line ◽  
Contact Angles ◽  
Strong Interactions ◽  
Interfacial Behavior ◽  
Ceramic Substrates ◽  
Sic Ceramic ◽  
Mo Content ◽  
Drop Technique

The Mo-Ni (Co)-Si metallizing coatings on the SiC ceramic substrate were prepared by vacuum cladding process. The wetting and spreading of molten Al on coated SiC ceramic substrates at 900 oC were investigated by the sessile drop technique, and the interfacial behavior of the Al/coated SiC wetting couples was analyzed. The experimental results showed that the final contact angle of Al/M20NiSi coated SiC was close to 0o. With the increase of Mo content in the Mo-Ni-Si coating, the shape of the sessile drop became very irregular due to the strong interactions between the Al drop and the coating, so it was unable to precisely characterize the contact angles of Al/Mo30NiSi and Al/Mo40NiSi systems. The final contact angle of Al/Mo10CoSi coated SiC system was also close to 0o, however, the final contact angle of Al/Mo20CoSi coated SiC system climbed to ~42o with the Mo content increasing from 10 at.% to 20 at.%. The significant increase of contact angle may be caused by the accumulation of Mo near the triple line which can impede the spreading of Al drop.

The Wetting of Insect Cuticles by Water

1955 ◽  
Vol 32 (3) ◽  
pp. 591-617 ◽  
Author(s):  
M. W. HOLDGATE
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Properties ◽  
Surface Composition ◽  
Contact Angles ◽  
Aquatic Species ◽  
Water Contact ◽  
Calliphora Erythrocephala ◽  
Wetting Properties ◽  
Wide Range

1. The water contact angles of insects show a wide range of variation, which is broadly correlated with surface roughness and with habitat. 2. The contact angles of species inhabiting stored products or carrion are greatly modified by contamination. This produces large variations between apparently similar individuals. 3. In terrestrial insects surface roughness increases the contact angles to very large apparent values. Detailed analyses of its effect have been made in the pupa of Tenebrio molitor and the adult Calliphora erythrocephala. In some aquatic insects surface roughness leads to a reduction in the contact angles; this has been studied in the nymph of Anax imperator. 4. Prolonged immersion in water causes a lowering of the contact angles of all the insects examined, and the low angles of many aquatic species may therefore be the direct effect of their environment. In some aquatic species there is evidence of the active maintenance of a large contact angle during life. 5. Changes in contact angle accompany processes of cuticle secretion and will occur at any moult if changes in roughness or habitat take place. 6. The observed variations of surface properties can be explained without assuming any variation in the chemical composition of the cuticle surface. Wetting properties are of little value as indicators of cuticle surface composition. 7. The biological aspects of insect surface properties are briefly discussed.

Wetting Effects on Two-Phase Flow in a Microchannel

2007 ◽  
Author(s):  
Alexandru Herescu ◽  
Jeffrey S. Allen
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Water Flow ◽  
High Speed ◽  
Two Phase Flow ◽  
Contact Angles ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Number Systems

In the recent years there has been an increasing interest in the study of two-phase flows in low Bond number systems (where capillary forces are important relative to gravitational forces). Such systems include capillary tubes and microchannels as well as the gas flow channels of a PEM fuel cell. At the capillary scale, surface tension forces play an important role in two-phase flow regime transitions, pointing out the need to take into account the geometry of the cross section and the surface properties (wettability). Surface tension is generally considered in flow transitions, but the wetting properties of the fluid-surface material pairs (contact angle) are rarely given any importance. The researchers investigating two-phase flows should take extreme care when choosing the material of the test sections, as the flow morphology and the the pressure drop accordingly can vary widely with contact angle. In order to show these morphological changes high speed visualization experiments of air-water flow through 500 μm square and round microchannels were conducted. For the round channels, contact angles of less than 20° (wetting) and 105° (non-wetting) were investigated. For the square section, things are complicated by the presence of the corners. According to the Concus-Finn criterion, the liquid will wick into (wet) the corner if the contact angle is less then 45°, or will de-wet the corner if the contact angle is above 45°. A new case not previously mentioned in the literature arises for a contact angle of 45° ≤ θ ≤ 90°, for which the liquid is wetting the walls but dewetting the corners. Three contact angles of less than 20°, 80° and 105° are considered to investigate the possible morphologies in the square geometry. Images aquired with a high speed camera depicting the different flow morphologies that exist at the same air-water flow rates for each of the considered contact angle and geometry are presented.

scholarly journals Analysis of a Wide Range of Commercial Exterior Wood Coatings

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1013
Author(s):  
Michael J. Gibbons ◽  
Saeid Nikafshar ◽  
Tina Saravi ◽  
Katie Ohno ◽  
Sanjeev Chandra ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Water Uptake ◽  
Water Immersion ◽  
Contact Angles ◽  
Solid Content ◽  
Image Processing Technique ◽  
Wide Range ◽  
Water Based ◽  
Exterior Wood

This study was focused on measuring the properties of twenty-three commercially available coatings formulated for exterior wood applications. The coatings were characterized by measuring their surface tension, solid content, viscosity, pH, and glass transition temperatures (Tg). Additionally, the wetting properties of coating droplets on wood substrates were measured. The contact angle of solvent-based and water-based coatings were characterized on untreated southern yellow pine wood samples using high-resolution image analysis and the Young–Laplace solution. An innovative image processing technique for determining the average diameter of coating droplets on wood was developed, and an iterative method to calculate the average contact angle using the Young–Laplace solution was applied. The water-resistance of the coated wood samples was evaluated during one week of water immersion tests. In general, solvent-based coatings had significantly lower contact angles and water uptake than water-based coatings. Water-based paint samples had the largest average contact angle (81°), and solvent-based transparent penetrating stains had the smallest contact angle (13.9°). A strong correlation was observed between the coating water uptake and their surface tension and solid content.

scholarly journals Effect of CO2 Flooding on the Wettability Evolution of Sand-Stone

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5542
Author(s):  
Cut Aja Fauziah ◽  
Ahmed Al-Yaseri ◽  
Emad Al-Khdheeawi ◽  
Nilesh Kumar Jha ◽  
Hussein Rasool Abid ◽  
...  
Keyword(s):  
Contact Angle ◽  
Clay Content ◽  
Contact Angles ◽  
Co2 Injection ◽  
Co2 Flooding ◽  
Core Flooding ◽  
Before And After ◽  
Significant Research ◽  
Co2 Plume ◽  
Geological Co2 Sequestration

Wettability is one of the main parameters controlling CO2 injectivity and the movement of CO2 plume during geological CO2 sequestration. Despite significant research efforts, there is still a high uncertainty associated with the wettability of CO2/brine/rock systems and how they evolve with CO2 exposure. This study, therefore, aims to measure the contact angle of sandstone samples with varying clay content before and after laboratory core flooding at different reservoir pressures, of 10 MPa and 15 MPa, and a temperature of 323 K. The samples’ microstructural changes are also assessed to investigate any potential alteration in the samples’ structure due to carbonated water exposure. The results show that the advancing and receding contact angles increased with the increasing pressure for both the Berea and Bandera Gray samples. Moreover, the results indicate that Bandera Gray sandstone has a higher contact angle. The sandstones also turn slightly more hydrophobic after core flooding, indicating that the sandstones become more CO2-wet after CO2 injection. These results suggest that CO2 flooding leads to an increase in the CO2-wettability of sandstone, and thus an increase in vertical CO2 plume migration and solubility trapping, and a reduction in the residual trapping capacity, especially when extrapolated to more prolonged field-scale injection and exposure times.

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