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liquid-interface
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Characterization of interfacial hydrodynamics in a single cell of shaken microtiter plate bioreactors applying computational fluid dynamics technique
, Article Procedia Engineering ; Volume 42 , 2012 , Pages 924-930 ; 18777058 (ISSN) ; Amoabediny, G ; Sadegh Saghafinia, M ; Haji Abbas, M. P ; Sharif University of Technology
2012
Abstract
Development of orbital shaking technology for enhanced mixing with lower mechanical demand has been receiving significant attention since the advent of advanced mixing schemes. Amongst shaken bioreactors, microtiter plates play significant role both for research and industrial purposes due to their capability of handling tiny amount of liquid in parallel experimentations. Detailed understanding of complicated Flow hydrodynamics thus seems to be considered a continual effort, as it is responsible for efficient gas-liquid mass transfer. Computational fluid dynamics (CFD) technique is shown to be a suitable numerical method in particular for discovering concealed flow facts, which can reliably...
A more accurate prediction of liquid evaporation flux
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 23, Issue 2 , 2004 , Pages 45-53 ; 10219986 (ISSN) ; Sabzyan, H ; Zeini Isfahani, A ; Parsafar, G ; Sharif University of Technology
Iranian Journal of Chemistry and Chemical Engineering
2004
Abstract
In this work, a more accurate prediction of liquid evaporation flux has been achieved. The statistical rate theory approach, which is recently introduced by Ward and Fang and exact estimation of vapor pressure in the layer adjacent to the liquid-vapor interface have been used for prediction of this flux. Firstly, the existence of an equilibrium layer adjacent to the liquid-vapor interface is considered and the vapor pressure in this layer and its thickness calculated. Subsequently, by using the Fick's second law, an appropriate vapor pressure expression for the pressure of equilibrium layer is derived and by this expression and the statistical rate theory approach, evaporation flux is...
A note on the synergistic effect of surfactants and nanoparticles on rising bubble hydrodynamics
, Article Chemical Engineering and Processing - Process Intensification ; Volume 155 , 2020 ; Bastani, D ; Lotfi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Various mixtures of surfactants and nanosilica particles were investigated to assess their influence on rising bubble hydrodynamics. For this purpose, local velocities of rising bubbles were measured experimentally. Also, the effects of concentration of three types of surface-modified silica nanoparticles on density, viscosity, and surface tension of surfactant solutions were determined. Experimental results revealed that the simultaneous presence of nanoparticles and surfactant molecules led to the decrease of local velocities of rising bubbles. The presence of nanoparticles in surfactant solutions leads to a more reduction of bubble local velocity. This could be caused by the formation of...
Calcium chloride adsorption at liquid-liquid interfaces: A molecular dynamics simulation study
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 527 , 2017 , Pages 70-80 ; 09277757 (ISSN) ; Bahramian, A ; Chen, P ; Pourafshary, P ; Goddard, W.A., III ; Ejtehadi, M. R ; Sharif University of Technology
Abstract
We carried out molecular dynamics simulations (MD) to investigate the adsorption of calcium chloride (CaCl2) at n-hexane-water interfaces. We also measured the interfacial tensions (IFT) of the selected systems making use of the pendant-drop method. The histograms of hexane, water, and the ions indicate an electrical double layer (EDL) near the interface. The trend of the EDL indicates that chloride anions intend to adsorb to the interface more intrinsically than calcium cations. The measured interfacial width of the n-hexane-water interfaces decreases with the salt concentration. The average densities of the interfacial and bulk aqueous solutions demonstrate density heterogeneity in the...
A model based on the equality of chemical potentials for describing the liquid-liquid interfaces of water-hydrocarbons up to high pressures
, Article Journal of Molecular Liquids ; Volume 317 , November , 2020 ; Feyzi, P ; Tourang, S ; Tajfar, F ; Sharif University of Technology
Elsevier B. V
2020
Abstract
A reliable model was used to describe the interfacial tension, composition, and density of the liquid-liquid interfaces of water-hydrocarbons. The parachor model was combined with the equality of the chemical potential of components at the interface and the bulk liquid. The fugacity coefficient was used for computing chemical potentials. To compute the fugacity coefficients of the components, various types of equations of state (The Valderrama Patel-Teja, cubic plus association, and the simplified Perturbed-Chain Statistical Association Fluid Theory) were utilized. These models were applied to the temperature and the pressure range of (285.65–423) K and (1–3000) bar, respectively. The...
Investigating the Effect of Chemical Composition on the Anisotropy of Solid-Liquid Interfacial Energy of Nickel-Niobium Alloy
, M.Sc. Thesis Sharif University of Technology ; Tavakoli, Rouhollah (Supervisor)
Abstract
Although the anisotropy of the solid-liquid interfacial free energy for most metal alloys is small, this anisotropy plays a significant role in the growth rate, morphology, and preferred crystallographic directions in dendritic growth. In recent research, the binary nickel-niobium alloy has been suggested as a suitable substitute for studying the solidification behavior of the superalloy Inconel 718. In this study, using molecular dynamics simulation with the LAMMPS software, pure nickel and Ni-%1Nb, Ni-%5Nb, and Ni-%10Nb alloys were examined (composition is based on atomic percent). After equilibrating the liquid and solid phases at the melting temperature, the interfacial phase was studied...
Simplified model for polyurethane foaming in porous media
, Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 27, Issue 1 , 2017 , Pages 142-155 ; 09615539 (ISSN) ; Bazkhane, S ; Sharif University of Technology
Emerald Group Publishing Ltd
2017
Abstract
Purpose - The purpose of the study is to present a simplified model to replace the complicated foaming simulations for investigating the liquid polyurethane behavior just before solidification. Design/methodology/approach - This model is inspired from the traveling heater method of crystallization because of the low injection velocity. Besides, the heat generated during the reaction is considered as a heat source function in the energy equation. Findings - Various distributions of the heat generation function inside the geometry have been studied to choose the most realistic one. Effect of parameters such as the soil material and porosity on the temperature distribution and flow field are...
A comprehensive review on recent advances in superhydrophobic surfaces and their applications for drag reduction
, Article Progress in Organic Coatings ; Volume 140 , March , 2020 ; Pakzad, H ; Moosavi, A ; Nouri Borujerdi, A ; Sharif University of Technology
Elsevier B. V
2020
Abstract
Nowadays, superhydrophobic surfaces have attracted a lot of interest because of the wide range of applications in industries. These surfaces can significantly reduce the drag force due to the formation of air gaps between the substrate and liquid interface. The present review mainly focuses on the very recent progresses in the drag reduction studies using superhydrophobic surfaces. Also, a brief discussion about the mathematical modeling and the theories of superhydrophobic surfaces, natural water repellent surfaces, various fabrication techniques with advantages and disadvantages of each method and different properties of the fabricated surfaces in industrial applications is presented....
Adsorption dynamics of surface-modified silica nanoparticles at solid-liquid interfaces
, Article Langmuir ; Volume 38, Issue 41 , 2022 , Pages 12421-12431 ; 07437463 (ISSN) ; Bastani, D ; Mohammadi, A ; Kordzadeh, A ; Sharif University of Technology
American Chemical Society
2022
Abstract
Understanding the adsorption dynamics of nanoparticles at solid-liquid interfaces is of paramount importance to engineer nanoparticles for a variety of applications. The nanoparticle surface chemistry is significant for controlling the adsorption dynamics. This study aimed to experimentally examine the adsorption of surface-modified round-shaped silica nanoparticles (with an average diameter of 12 nm), grafted with hydrophobic (propyl chains) and/or hydrophilic (polyethylene glycol chains) agents, at an aqueous solution-silica interface with spherical soda-lime glass beads (diameter of 3 mm) being used as adsorbents. While no measurable adsorption was observed for solely hydrophobic or...
Dynamics of liquid interfaces under various types of external perturbations
, Article Current Opinion in Colloid and Interface Science ; Vol. 19, issue. 4 , Aug , 2014 , p. 309-319 ; Karbaschi, M ; Javadi, A ; Mucic, N ; Kragel, J ; Kovalchuk, V. I ; Rubio, R. G ; Fainerman, V. B ; Miller, R ; Sharif University of Technology
Abstract
Dynamic interfacial parameters are the key properties of interfaces in many modern technologies and can be studied in various ways. For applications like foams and emulsions, the dynamics of adsorption and the dilational and shear rheology of liquid-fluid interfaces are investigated most frequently. This work gives an insight into recently developed new experimental approaches, such as fast capillary pressure tensiometry for growing and oscillating drops. These experiments are presented in comparison to more classical techniques like drop profile tensiometry and capillary wave damping. Progress in these experiments based on generated interfacial perturbations can be expected only by a close...
Effects of ion-exchange and hydrolysis mechanisms on lead silicate glass corrosion
, Article Corrosion ; Volume 68, Issue 9 , September , 2012 , Pages 793-800 ; 00109312 (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
2012
Abstract
Corrosion of lead silicate glass (LSG) contacting 0.5 M aqueous nitric acid (HNO 3) was investigated via scanning electron microscopy, energy-dispersive spectroscopy, inductively coupled plasma analysis, and weight-loss measurement to determine the respective contributions of the ion-exchange vs. the hydrolysis reactions. The LSG having X M ≡ Pb+K+Na/Si mole ratios of less than 0.7 showed very little weight loss with no Si network deterioration. At X M > 0.7, the mechanism changed into the hydrolysis, which caused the formation of a networkless gel layer resting at the solid/liquid interface. Addition of titania (TiO 2) and zirconia (ZrO 2) had disparate effects: X M < 0.7 improved corrosion...
The effect of gap size on the microstructure and mechanical properties of the transient liquid phase bonded FSX-414 superalloy
, Article Materials and Design ; Volume 40 , September , 2012 , Pages 130-137 ; 02641275 (ISSN) ; Ekrami, A ; Sharif University of Technology
Elsevier
2012
Abstract
Optimization of transient liquid phase (TLP) bonding variables is essential to achieve a joint free from deleterious intermetallic constituents as well as with appropriate mechanical properties. In this research, TLP bonding of FSX-414 superalloy was performed using the MBF-80 interlayer. The effects of bonding time (1-30. min) and gap size (25-100 μm) were studied on the joint microstructure and its mechanical properties. Continuous centerline eutectic phases, characterized as nickel-rich and chromium-rich borides, were observed at the joints with incomplete isothermal solidification. The globular and acicular phases were seen at diffusion affected zone (DAZ). These phases could be...
The effect of TLP bonding temperature on microstructural and mechanical property of joints made using FSX-414 superalloy
, Article Materials Science and Engineering A ; Volume 546 , June , 2012 , Pages 291-300 ; 09215093 (ISSN) ; Ekrami, A ; Khan, T. I ; Sharif University of Technology
2012
Abstract
The bonding temperature is an important parameter for optimization of the Transient Liquid Phase (TLP) bonding process in order to achieve a sound joint with good mechanical properties. However, the bonding temperature used can also be restricted by the microstructural stability of the base metal. In this study, the effect of bonding temperature (1050-1200 °C) on the joint microstructure and mechanical properties was studied for TLP bonding of FSX-414 superalloy using MBF-80 interlayer with thickness of 50 μm. Increasing bonding temperature from 1050 to 1150 °C caused reduction in the time required for complete isothermal solidification in agreement with models based on the diffusion induced...
Pool boiling heat transfer in dilute water/triethyleneglycol solutions
, Article Chinese Journal of Chemical Engineering ; Volume 17, Issue 4 , 2009 , Pages 552-561 ; 10049541 (ISSN) ; Safekordi, A. A ; Jamialahmadi, M ; Sharif University of Technology
Abstract
Boiling of water/triethyleneglycol (TEG) binary solution has a wide-ranging application in the gas processing engineering. Design, operation and optimization of the involved boilers require accurate prediction of boiling heat transfer coefficient between surface and solution. In this investigation, nucleate pool boiling heat transfer coefficient has been experimentally measured on a horizontal rod heater in water/TEG binary solutions in a wide range of concentrations and heat fluxes under ambient condition. The present experimental data are correlated using major existing correlations. In addition a correlation is presented for prediction of pool boiling heat transfer for the system in which...
Characterization of liquid bridge formed during gas-oil gravity drainage in fractured porous media
, Article 16th European Conference on the Mathematics of Oil Recovery, ECMOR 2018, 3 September 2018 through 6 September 2018 ; 2018 ; 9789462822603 (ISBN) ; Masihi, M ; Ghazanfari, M. H ; Shoushtari, A ; Sharif University of Technology
European Association of Geoscientists and Engineers, EAGE
2018
Abstract
Gas-oil gravity drainage that takes place in the gas-invaded zone of fractured reservoirs is the main production mechanism of gas-cap drive fractured reservoirs as well as fractured reservoirs subjected to gas injection. Interaction of neighboring matrix blocks through reinfiltration and capillary continuity effects controls the efficiency of gravity drainage. Existence of capillary continuity between adjacent matrix block is likely to increase the ultimate recovery significantly. Liquid bridge formed in fractures has a significant role in maintaining the capillary continuity between two neighboring matrix blocks. The degree of capillary continuity is proportional to capillary pressure in...
Interfacial instability of growing drop: experimental study and conceptual analysis
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 347, Issue 1-3 , 2009 , Pages 167-174 ; 09277757 (ISSN) ; Bastani, D ; Kragel, J ; Miller, R ; Sharif University of Technology
Elsevier
2009
Abstract
Capillary pressure experiments were performed at the water/hexane interface including adsorption and mass exchange of hexanol under different conditions. The results from growing drop experiments show that instabilities due to Marangoni convection not only depend on the same parameters as have been reported for quasi-static interfaces, such as direction of mass transfer, distribution coefficient and ratio of diffusion coefficients, but also on the experimental conditions such as dispersed phase flow rate, capillary tip size, size of growing drop and its lifetime. Based on a new flow expansion model for mass transfer, a new approach is presented for data analysis, which includes the various...
Marangoni instabilities for convective mobile interfaces during drop exchange: Experimental study and CFD simulation
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 441, issue , 2014 , pp. 846-854 ; ISSN: 09277757 ; Karbaschi, M ; Bastani, D ; Ferri, J. K ; Kovalchuk, V. I ; Kovalchuk, N. M ; Javadi, K ; Miller, R ; Sharif University of Technology
Abstract
The inflow pattern of liquid into a droplet is studied experimentally using a surface active dye and compared with results of CFD simulations. The results show visual agreement between experiments and simulations. The CFD simulations show also good agreement with the surface tension measured by drop profile analysis tensiometry (PAT). The inflow of the surfactant induces a Marangoni instability caused by the local arrival of the surfactant at the drop surface. The onset of this Marangoni instability observed experimentally has a delay of about 10. s when compared with the simulation results. Different scenarios are discussed, including a boundary layer barrier, a kinetic-controlled...
Formation mechanism of bead-chain-like ZnO nanostructures from oriented attachment of Zn/ZnO nanocomposites prepared via DC arc discharge in liquid
, Article Materials Science in Semiconductor Processing ; Volume 72 , 2017 , Pages 128-133 ; 13698001 (ISSN) ; Poursalehi, R ; Naseri, N ; Sharif University of Technology
Abstract
Bead-chain-like ZnO nanoparticles (NPs) formed in colloidal solution from oriented attachment (OA) of spherical nanoparticles. Arc discharge in liquid is a cost-effective method for quick mass production of nanostructured materials without considerable environmental footprints. Applying voltage across two zinc rods as electrodes, which were immersed in water cause explosion of electrodes and plasma generation. Zn/ZnO nanocomposites produced by interaction of different active species in high-pressure and high-temperature plasma at the solid-liquid interface. Different sized nanoparticles with diameters of 26, 35, 40 and 60 nm at applied discharge currents of 150, 100, 50 and 20 A...