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    Effect of magnetic field treatment on interfacial tension of CTAB nano-emulsion: developing a novel agent for enhanced oil recovery

    , Article Journal of Molecular Liquids ; Volume 261 , July , 2018 , Pages 107-114 ; 01677322 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2018
    Nanoemulsion is a novel type of emulsified solutions holding great promises for utilizing in industrial applications. Although microemulsions have been the subject of numerous studies in past decades, however, nanoemulsions are quite virgin and merit detailed investigation to scrutinize their characteristics specific to reservoir engineering, in particular, Enhanced Oil Recovery (EOR). To this end, the present study is an attempt to evaluate the effectiveness of a specific nanoemulsion for oil displacement through porous media. In this regard, flooding experiments were designed and Hexa decyl trimethylammonium bromide (CTAB), which is a cationic surfactant, was used as the emulsifying agent.... 

    Densities, viscosities, and surface tensions of aqueous mixtures of sulfolane + triethanolamine and sulfolane + diisopropanolamine

    , Article Journal of Chemical and Engineering Data ; Volume 56, Issue 12 , 2011 , Pages 4317-4324 ; 00219568 (ISSN) Kelayeh, S. A ; Jalili, A. H ; Ghotbi, C ; Hosseini Jenab, M ; Taghikhani, V ; Sharif University of Technology
    Densities and viscosities of aqueous solutions containing sulfolane and ternary aqueous solutions of sulfolane and triethanolamine and ternary aqueous solutions containing sulfolane and disopropanolamine and also equilibrium surface tensions of the above ternary aqueous solutions were measured at temperatures ranging from (303.15 to 343.15) K and atmospheric pressure. The overall concentration of sulfolane, triethanolamine, and diisopropanolamine in solutions varied in the range of 0 to 16.5, 0 to 43, and 0 to 40 mass percent, respectively. Using the density, viscosity, and surface tension of pure water as the solvent, the corresponding experimental values obtained for the investigated... 

    Synthesis, Characterization and Hydrophobicity of Teflon Coated Tungsten Nanostructure Thin Films

    , M.Sc. Thesis Sharif University of Technology Bayat, Amir (Author) ; Moshfegh, Ali Reza (Supervisor) ; Azimirad, Rouhollah (Supervisor)
    Hydrophobic and superhydrophobic surfaces find many applications in different fields of science. The aerospace industry is one such field that can take the advantage of superhydrophobicity for anti-icing coatings. In order to make hydrophobic and superhydrophobic surfaces on hydrophilic materials, two-step process is usually need, at first, making a rough surface and then modifying it with hydrophobic coatings with low surface free energy. In this research, we have used glancing angle deposition (GLAD) RF sputtering technique to fabricate Teflon coated tungsten on glass substrate for obtaining hydrophobic surface. GLAD approach is a method to grow structures such as nanorods and zigzag... 

    Laser-Based Surface Tension Measurement

    , M.Sc. Thesis Sharif University of Technology Amini, Mansoureh (Author) ; Seyed Reihani, Morteza (Supervisor)
    Surface tension is the most important interfacial parameter of a liquid. This quantity plays a key role in many processes such as extraction, distillation, absorption and chemical reactions. Various methods are proposed for measuring this quantity among which, the laser based methods are the most accurate ones. Unlike most of the mechanical methods, laser based methods remotely measure the surface tension. The aim of the current thesis is to measure the surface tension using laser beam, more specifically using homodyne detection system. This method implemented in both reflected and transmitted modes. In each of the mentioned methods, first the laser beam was incident to the liquid-air... 

    Density and temperature dependencies of liquid surface tension

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 2 , 2011 , Pages 79-90 ; 10219986 (ISSN) Alizadeh Osgouei, H ; Parsafar, G. A ; Akbarzadeh, H ; Sharif University of Technology
    In this paper the density and temperature dependencies of surface tension are investigated. Using the Lennard-Jones (12,6), as an effective pair interaction potential, a linear expression is derived for isotherms of γ /ρ 2 versus ρ 2 for some normal and ChloroFluoroCarbons (CFCs) fluids, where is surface tension and ρ = 1/v is molar density. The linearity behavior of the derived equation is well fitted onto the experimental data of surface tension for monatomic, diatomic, nonpolar, polar, hydrogen-bonded and chlorofluorocarbons. In addition, the temperature dependence of surface tension for 20 different fluids is examined, in which the contributions of both terms of the average effective... 

    Multiphase simulation of liquid jet breakup using smoothed particle hydrodynamics

    , Article International Journal of Modern Physics C ; Volume 28, Issue 4 , 2017 ; 01291831 (ISSN) Pourabdian, M ; Omidvar, P ; Morad, M. R ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2017
    This paper deals with numerical modeling of two-phase liquid jet breakup using the smoothed particle hydrodynamics (SPH) method. Simulation of multiphase flows involving fluids with a high-density ratio causes large pressure gradients at the interface and subsequently divergence of numerical solutions. A modified procedure extended by Monaghan and Rafiee is employed to stabilize the sharp interface between the fluids. Various test cases such as Rayleigh-Taylor instability, two-phase still water and air bubble rising in water have been conducted, by which the capability of accurately capturing the physics of multiphase flows is verified. The results of these simulations are in a good... 

    Comparative approach for detection of biosurfactant-producing bacteria isolated from Ahvaz petroleum excavation areas in south of Iran

    , Article Annals of Microbiology ; Volume 58, Issue 3 , 2008 , Pages 555-559 ; 15904261 (ISSN) Afshar, S ; Bagheri Lotfabad, T ; Roostaazad, R ; Rouholamini Najafabadi, A ; Akbari Noghabi, K ; Sharif University of Technology
    University of Milan  2008
    The current study was undertaken to compare four analytical methods including drop collapse, oil spreading, surface tension (SFT) measurements, and blood agar lysis tests for detection of biosurfactant-producing bacteria. Among 32 biosurfactant-producing bacteria isolated from Ahvaz oil fields, in south of Iran, 16 isolates (50%) exhibited highest biosurfactant production. Eleven isolates (MASH.1 to MASH.11) demonstrated a reduction in surface tension from 65 mN/m to less than 41 mN/m. The results showed that about 91% of these highly biosurfactant producers had the same response levels of "++++" and "+++" in the case of both SFT and oil spreading methods. Among these, seven isolates had the... 

    Flow physics exploration of surface tension driven flows

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 518 , 2017 , Pages 30-45 ; 09277757 (ISSN) Javadi, K ; Moezzi Rafie, H ; Goodarzi Ardakani, V ; Javadi, A ; Miller, R ; Sharif University of Technology
    Surface tension driven passive micro-pumping relies mainly on the surface tension properties. To have control over surface tension driven passive micro-pumps (STD-PMPs), it is essential to understand the physical background of the fluid flow in these pumps. Hence, the purpose of this work is to give an exploration of the flow physics of a STD-PMP. In this regard, computer simulation is used to give detailed information about the flow pattern and physical phenomena at different conditions. To this end, a droplet of water, with a specified diameter, is placed onto an entry port connected to another droplet at the exit port via a microchannel. The results indicate that the pumping process, in... 

    An ISPH scheme for numerical simulation of multiphase flows with complex interfaces and high density ratios

    , Article Computers and Mathematics with Applications ; Volume 75, Issue 8 , 2018 , Pages 2658-2677 ; 08981221 (ISSN) Rezavand, M ; Taeibi Rahni, M ; Rauch, W ; Sharif University of Technology
    Elsevier Ltd  2018
    Multiphase problems with high density ratios and complex interfaces deal with numerical instabilities and require accurate considerations for capturing the multiphase interfaces. An Incompressible Smoothed Particle Hydrodynamics (ISPH) scheme is presented to simulate such problems. In order to keep the present scheme simple and stable, well-established formulations are used for discretizing the spatial derivatives and a repulsive force is applied at the multiphase interface between particles of different fluids to maintain the interface sharpness. Special considerations are included to overcome the difficulties to model severe physical discontinuities at the interface and surface tension... 

    An insight into the formation of liquid bridge and its role on fracture capillary pressure during gravity drainage in fractured porous media

    , Article Canadian Journal of Chemical Engineering ; Volume 99, Issue S1 , 2021 , Pages S212-S231 ; 00084034 (ISSN) Harimi, B ; Masihi, M ; Ghazanfari, M. H ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    The formation of liquid bridges can maintain capillary continuity between matrix blocks during gas/oil gravity drainage in fractured reservoirs. A travelling oil drop draining into a fracture either forms a liquid bridge or breaks into detached drops. However, the different characteristics of a travelling drop during its elongation and required conditions for transformation into a liquid bridge are not well described in the published literature. In this work, a one-dimensional model based on slender-drop theory is employed that holds gravity, viscosity, and surface tension forces but ignores inertia. This model, together with Young-Laplace equation, gives the fracture capillary pressure.... 

    Simulation of Multiphase Flow in Non-Circular Capillaries Using SPH

    , M.Sc. Thesis Sharif University of Technology Fayazbakhsh, Mohammad Ali (Author) ; Kazemzadeh Hannani, Siamak (Supervisor) ; Taghizadeh Manzari, Mehrdad (Supervisor)
    In this thesis an SPH method is used for simulating multiphase two- and three-dimensional Newtonian fluid flows. The weakly compressible algorithm consists of two steps of prediction and correction. In the prediction step, the velocity field is integrated forward in time without enforcing incompressibility. The correction step consists of enforcing incompressibility by solving the pressure Poisson equation which creates a trade-off between the pressure and density variations. The surface tension force is applied in the linear momentum conservation equation by the divergence of the surface stress tensor. Advanced techniques are applied to achieve better convergence and reduce pressure-related... 

    Experimental Study and Modeling of Thermodynamic Stability of the Oil and Water Emulsions in the Presence of Surfactants And Different Degrees of Temperature

    , M.Sc. Thesis Sharif University of Technology Moeini, Farzaneh (Author) ; Ghotbi, Cyrus (Supervisor) ; Taghikhani, Vahid (Supervisor)
    Always, understanding the properties of crude oil and related phenomena of that has been noticeable matter. Surface tension is one of the important fluid properties and the evaluation of that is essential in oil industry especially in enhanced oil recovery method (EOR) and transport of crude oil by using emulsions.
    In this research, interfacial tension (IFT) was measured via pendant drop method. The effect of three parameters was investigated on IFT for creating of stable oil/water emulsion. These parameters were temperature, concentration of surfactants, and salinity. They were varied between 25-65 ᵒC, 0.05-0.2 gr and 5000ppm respectively. It was used two types of surfactant; acid... 

    Nanoparticles and Surfactants Complex Effects on Water Evaporation

    , M.Sc. Thesis Sharif University of Technology Behnejhad Takleh, Katayoun (Author) ; Bastani, Dariush (Supervisor) ; Jvadi, Aliyar (Supervisor)
    Interest in the study of evaporation of liquid droplets is associated with a variety of practical applications, ranging from fuel burning and intensification of heat and mass transfer processes to formation of nanostructures. The study of the evaporation of liquid droplets is a fundamental problem, and it is the subject of a large number of works. However, in droplet evaporation processes, there are still many fundamental issues requiring more in-depth studies. In this study, the effect of the presence of hydrophilic silica nanoparticles and cationic (CTAB), anionic (SDS) and nonionic (TX-100) surfactants separately and in combination on the evaporation rate of water in a pendant droplet... 

    Dependence of Surface Tension on Temperature and Density in the Interface of Liquid & Vapour

    , M.Sc. Thesis Sharif University of Technology Khorsandi, Zahra (Author) ; Parsafar, GholamAbbas (Supervisor)
    In this thesis dependency of surface tension ( ) on temperature (T ) and density (?), for spherical and nearly spherical fluids like argon has been investigated, using an effective Lennard – Jones (12,6) potential along with a new model according to which half of surface molecules are assumed to be in the liquid phase and the other half in the vapor phase, far from the critical point. The obtained result may be expressed as ? ? ? ( The 2 2= +C D C and D parameters are independent of T and ?). Such an investigation has also been done for many fluids, but by using the extended Lennard – Jones (12, 6, 3) function as the effective pair... 

    Study of water entry of circular cylinder by using analytical and numerical solutions

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 34, Issue 3 , July , 2012 , Pages 225-232 ; 16785878 (ISSN) Ghadimi, P ; Dashtimanesh, A ; Djeddi, S. R ; Sharif University of Technology
    Water impact phenomenon in the case of a circular cylinder is an important issue in offshore industry where cross members may be in the splash zone of the incident wave. An analytical method as well as a numerical solution are employed to study the water entry problem of a circular section. The procedure for derivation of the analytical formulas is demonstrated step by step. The volume of fluid (VOF) simulation of the water entry problem is also performed to offer comparison of the results of the linearized analytical solution with a fully nonlinear and viscous fluid flow solution. To achieve this, the FLOW- 3D code is utilized. Some consideration has also been given to the points of... 

    A modified square well model in obtaining the surface tension of pure and binary mixtures of hydrocarbons

    , Article Journal of Chemical Thermodynamics ; Volume 40, Issue 7 , 2008 , Pages 1131-1135 ; 00219614 (ISSN) Bitaab, A ; Taghikhani, V ; Ghotbi, C ; Ayatollahi, S ; Sharif University of Technology
    A model based on the perturbation theory of fluids was proposed to correlate the experimental data for surface tension of pure hydrocarbons in a wide range of temperature. The results obtained for the pure hydrocarbons were directly used to predict the surface tension for binary hydrocarbon mixtures at various temperatures. In the proposed model, a modified form of the square well potential energy between the molecules of the reference fluid was taken into account while the Lennard-Jones dispersion energy was considered to be dominant amongst the molecules as the perturbed term to the reference part of the model. In general, the proposed model has three adjustable parameters which are chain... 

    Drop profile analysis tensiometry under highly dynamic conditions

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 413 , 2012 , Pages 292-297 ; 09277757 (ISSN) Karbaschi, M ; Bastani, D ; Javadi, A ; Kovalchuk, V. I ; Kovalchuk, N. M ; Makievski, A. V ; Bonaccurso, E ; Miller, R ; Sharif University of Technology
    Profile analysis tensiometry (PAT) is presently the most frequently used technique for measuring surface tensions of liquids. The basis of this methodology is however an equilibrium force balance as given by the Gauss-Laplace equation. Therefore, its application under dynamic conditions, i.e. for growing drops or bubbles, is questionable. We discuss the limits of the applicability of PAT under dynamic conditions by using a growing drop configuration equipped with a high speed video camera. The systems studied are the water/air and water/hexane interface. The obtained "dynamic" drop profiles are analyzed by fitting the classical Gauss-Laplace equation. The results are additionally compared... 

    Adsorption of proteins at the solution/air interface influenced by added non-ionic surfactants at very low concentrations for both components. 1. Dodecyl dimethyl phospine oxide

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 475, Issue 1 , June , 2015 , Pages 62-68 ; 09277757 (ISSN) Lotfi, M ; Javadi, A ; Lylyk, S. V ; Bastani, D ; Fainerman, V. B ; Miller, R ; Sharif University of Technology
    The adsorption of proteins at liquid interfaces happens at rather low bulk concentrations due to their rather high surface activity. In contrast typical surfactants start to decrease the surface tension at bulk concentration in the range of mmol/l and reach a minimum value at about two or three orders of magnitude higher concentration. The two proteins studied here, β-lactoglobulin and β-casein, adsorb already remarkably at much lower concentrations, i.e. less than 1. μmol/l. When smallest amounts of a non-ionic surfactant are added to low concentrated protein solutions, changes in the surface tension are observed which cannot be explained by the existing theoretical models. An agreement... 

    Experimental Investigation of Oil Production by Low IFT Dynamic Imbibition

    , M.Sc. Thesis Sharif University of Technology Harimi, Behrouz (Author) ; Masihi, Mohsen (Supervisor)
    Imbibition process is known to be an important recovery mechanism in naturally fractured reservoirs with water-wet matrix blocks that are imposed to water influx from an active aquifer or water flooding. Matrix blocks which are subjected to water flooding or water invasion from active aquifers do not become immersed in water at once, but they experience gradual rising of water in fracture. But most of imbibition studies are performed under conditions of totally immersed cores in static aqueous phase. Surfactants are known to reduce residual oil saturation by decreasing interfacial tension (IFT) between oil and water. On the other hand, considerable reduction of IFT due to surfactant... 

    Measurement of Thermophysical Properties of Aqueous Solutions of Alkanolamine

    , M.Sc. Thesis Sharif University of Technology Ahmadkelayeh, Sarah (Author) ; Ghotbi, Siroos (Supervisor) ; Taghikhani, Vahid (Supervisor) ; Jalili, Amir Hossin (Supervisor)
    In this study, density, viscosity and surface tension of aqueous solution of Sulfolane, ( TEA+TMS+H2O) and (DIPA+TMS+H2O) systems were measured . Density, viscosity and surface tension were measured using pycnometer, Cannon – Fenske viscometer and Capillary rise method, respectively. Surface tension measurements of (DIPA+TMS+water) were carried out by the ring method using a LAUDR TD3 tensiometer,. The experiments were carried out in low concentrations and atmospheric pressure in the temperature range (70 - 30) . The obtained Data was modeled using empirical and thermodynamic models. Density calculation was done using the Setchenov and Redlich – Kister models.and the results indicated that...