Loading...
Search for: drops
0.008 seconds
Total 420 records

    Experimental flow visulization of single swirl spray pattern at various pressure drops

    , Article 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2003, Huntsville, AL, 20 July 2003 through 23 July 2003 ; 2003 ; 9781624100987 (ISBN) Ghorbanian, K ; Ashjaee, M ; Soltani, M. R ; Mesbahi, M. H ; Morad, M. R ; Sharif University of Technology
    2003
    Abstract
    An experimental investigation of the flow field of pressure swirl atomizers for different pressure drops is performed. Two experimental methods are employed. For low injection pressures, a visual study is conducted while for higher pressures the velocity components and size of the droplets are measured by using Phase Doppler Anemometer. The spray formation, spray cone angle, and breakup length are visually investigated. Velocity and size of the droplets are measured on a plane of measurement along the axis of the spray so that the properties are carried out in a radial direction as a function of both pressure drop and axial distance from the nozzle. Self-similar mean axial velocity profiles... 

    Neural network analysis of single swirl spray pattern at various pressure drops

    , Article 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2003, Huntsville, AL, 20 July 2003 through 23 July 2003 ; 2003 ; 9781624100987 (ISBN) Soltani, M. R ; Ghorbanian, K ; Ashjaee, M ; Morad, M. R ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2003
    Abstract
    Radial Basis Function, a neural network based interpolation method, is used to simulate swirling spray phenomenon. From this model, the profile of mean velocity components' distribution along the main axis of the injector at various pressure drops and spray measurements' plane are obtained and analyzed. Experimental data obtained through Phase Doppler Anemometer is used to train this model. The results are compared with experimental data as well as to those obtained through General Regression Neural Network method as another neural network based interpolation method investigated previously by the authors. © 2003 by M.R. Soltani  

    Applicability of lattice Boltzmann method in simulation of drops and bubbles formation and transport

    , Article AIP Conference Proceedings, 22 September 2014 through 28 September 2014 ; Volume 1648 , 2015 ; 0094243X (ISSN) ; 9780735412873 (ISBN) Taeibi Rahni, M ; Alizadeh, M ; Haghshenas, M ; Salimi, H ; Najafi, M ; Miller, R ; Sharif University of Technology
    Abstract
    Multiphase flows appear in many scientific and engineering applications. On the other hand, there has been a tremendous experimental and numerical investigation trying to understand complex fluid-fluid interfaces better. However, conventional CFD have certain limitations in complicated situations. Fortunately in the past two decades, new approaches, namely SPH and LBM (sometimes called meshless methods) have been developed. Since they are mesoscopic, they have been able to perform much better than conventional CFD. Especially, LBM is becoming more and more popular and has already been divided to many branches  

    Quantitative analysis of irreversibilities causes voltage drop in fuel cell (simulation & modeling)

    , Article Electrochimica Acta ; Volume 50, Issue 2-3 SPEC. ISS , 2004 , Pages 699-704 ; 00134686 (ISSN) Ghadamian, H ; Saboohi, Y ; Sharif University of Technology
    2004
    Abstract
    Power level of a fuel cell depends on its operating condition, which is product of voltage and current-density the highest level of voltage is identified as reversible open circuit voltage (ROCV), which represents an ideal theoretical case [J. Larmin, A. Dicks, Fuel Cell System Explained, Willy, 2000 (ISBN)]. Compared to that is ideal operating voltage which is usually characterized as open circuit voltage (OCV) [J. Larmin, A. Dicks, Fuel Cell System Explained, Willy, 2000 (ISBN)]. An evaluation of deviation of operating voltage level from ideal operational case may provide information on the extent of improving efficiency and energy efficiency of a fuel cell. Therefore, quantification of... 

    Enhancement effect of structured packing on the liquid-liquid mass transfer coefficients

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Bastani, D ; Ghasemian, S ; Dehkordi, A. M ; Sharif University of Technology
    2008
    Abstract
    The mass transfer coefficients of single drops in liquid-liquid extraction systems were studied using a single drop apparatus both with and without packing. The chemical system of n-butanol-succinic acid-water and the Structured Packing (SMV.350Y) were used in the liquid-liquid extraction. Based on the experimental results obtained for both mass transfer directions, in most cases, the structured packing had considerably enhanced the mass transfer coefficient by increasing the contact area between two phases and also increasing the contact time, especially in the contaminated systems. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process... 

    Innovations in non-linear oscillations of a pendent drop from a capillary tip during formation and detachment - an LBM simulation

    , Article Journal of Applied Fluid Mechanics ; Volume 14, Issue 1 , 2020 , Pages 331-344 Ghorbanifar, S ; Taeibi Rahni, M ; Zareh, M ; Sharif University of Technology
    Isfahan University of Technology  2020
    Abstract
    Individual drops are suitable tools to study the liquid-fluid interfacial properties. In this work, force-displacement equation and non-linear oscillations of a pendent drop are numerically investigated. The presented novel force-displacement function allows following the dynamics of a pendent drop and realizing its elastic behavior. The growth and detachment of drop, which is pending due to gravity from a capillary tip, is considered (assuming high density and high viscosity ratios and immiscible two-phase flows). Two-dimensional multi-relaxation time lattice Boltzmann method (MRT-LBM) was used to simulate growth, detachment, and oscillations of the drop using a conservative model for... 

    Modelling of mean drop size in a extraction spray column and developing a new model

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 4 , 2011 , Pages 89-96 ; 10219986 (ISSN) Ghorbanian, S. A ; Abolghasemi, H ; Radpour, S. R ; Sharif University of Technology
    2011
    Abstract
    Drop size distribution plays a key role in the liquid extraction systems and related hydrodynamic and mass transfer parameters. In current research work, the size of drops in an extraction spray column has been measured by direct photography method, and the Sauter mean diameter has been obtained accordingly. Then, two types of models are assessed based on using dimensionless analysis and appropriate software. The interfacial tension in used chemical system is 1.8-32 dyne/cm. In first type of models, the correlation is established based on dimensionless parameters similar to approaches defined by other researchers. In second types, dimensional parameters have been used and therefore a new... 

    Dynamics of drops - Formation, growth, oscillation, detachment, and coalescence

    , Article Advances in Colloid and Interface Science ; Volume 222 , 2015 , Pages 413-424 ; 00018686 (ISSN) Karbaschi, M ; Taeibi Rahni, M ; Javadi, A ; Cronan, C. L ; Schano, K. H ; Faraji, S ; Won, J. Y ; Ferri, J. K ; Krägel, J ; Miller, R ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Single drops or bubbles are frequently used for the characterization of liquid- fluid interfaces. Their advantage is the small volume and the various protocols of their formation. Thus, several important methods are based on single drops and bubbles, such as capillary pressure and profile analysis tensiometry. However, these methods are often applied under dynamic conditions, although their principles are defined under equilibrium conditions. Thus, specific attention has to be paid when these methods are used beyond certain limits. In many cases, computational fluid dynamics (CFD) simulations have allowed researchers, to extend these limits and to gain important information on the... 

    Theoretical and experimental study on the motion and shape of viscoelastic falling drops through Newtonian media

    , Article Rheologica Acta ; Volume 55, Issue 11-12 , 2016 , Pages 935-955 ; 00354511 (ISSN) Vamerzani, B. Z ; Norouzi, M ; Firoozabadi, B ; Sharif University of Technology
    Springer Verlag 
    Abstract
    In this paper, creeping motion of a viscoelastic drop falling through a Newtonian fluid is investigated experimentally and analytically. A polymeric solution of 0.08 % xanthan gum in 80:20 glycerol/water and silicon oil is implemented as the viscoelastic drop and the bulk viscous fluids, respectively. The shape and motion of falling drops are visualized using a high speed camera. The perturbation technique is employed for both interior and exterior flows, and Deborah and capillary numbers are considered as perturbation parameters up to second order. The product of Deborah and capillary numbers is also used as a perturbation parameter to apply the boundary condition on the deformation on the... 

    Analytical relations for long-droplet breakup in asymmetric T junctions

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 91, Issue 5 , May , 2015 ; 15393755 (ISSN) Bedram, A ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
    American Physical Society  2015
    Abstract
    We develop accurate analytical relations for the droplet volume ratio, droplet length during breakup process, and pressure drop of asymmetric T junctions with a valve in each of the branches for producing unequal-sized droplets. An important advantage of this system is that after manufacturing the system, the size of the generated droplets can be changed simply by adjusting the valves. The results indicate that if the valve ratio is smaller than 0.65, the system enters a nonbreakup regime. Also the pressure drop does not depend on the time and decreases by increasing the valve ratio, namely, opening the degree of valve 1 to valve 2. In addition, the results reveal that by decreasing... 

    Water drop impact on a semi-cylindrical convex hot surface for a diameter ratio of unity

    , Article Experimental Thermal and Fluid Science ; Volume 106 , 2019 , Pages 68-77 ; 08941777 (ISSN) Jowkar, S ; Morad, M. R ; Sharif University of Technology
    Elsevier Inc  2019
    Abstract
    When a liquid drop impacts on a hot non-flat surface the curvature of the surface and its geometrical characteristics transmute the physical regimes and their boundary compared to a flat surface impact. The present experimental study is focused on water drop impingement on a mimetic solid semi-cylindrical convex hot surface, with a size equal to the drop. The thermal versus inertia map of generated regimes is obtained, while some well-known regimes associated with a flat surface are not observed for the present non-flat impacts. These include rebounding of the main drop and atomization which are common observed phenomena when the hot surface is flat. The maximum spreading of the droplet is... 

    Analytical solution for creeping motion of a viscoelastic drop falling through a Newtonian fluid

    , Article Korea Australia Rheology Journal ; Vol. 26, issue. 1 , 2014 , pp. 91-104 ; ISSN: 1226119X Vamerzani, B. Z ; Norouzi, M ; Firoozabadi, B ; Sharif University of Technology
    Abstract
    In this paper, an analytical solution for steady creeping motion of viscoelastic drop falling through a viscous Newtonian fluid is presented. The Oldroyd-B model is used as the constitutive equation. The analytical solutions for both interior and exterior flows are obtained using the perturbation method. Deborah number and capillary numbers are considered as the perturbation parameters. The effect of viscoelastic properties on drop shape and motion are studied in detail. The previous empirical studies indicated that unlike the Newtonian creeping drop in which the drop shape is exactly spherical, a dimpled shape appears in viscoelastic drops. It is shown that the results of the present... 

    Experimental investigation of the effects of surfactant on the dynamics of formation process of liquid drops

    , Article Journal of Industrial and Engineering Chemistry ; Volume 89 , 2020 , Pages 183-193 Dastyar, P ; Salehi, M. S ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2020
    Abstract
    In the present study, the formation of surfactant-laden viscous drops in ambient air is experimentally investigated using a high-speed digital camera. The mixtures of 90%, 92.5%, and 95% glycerol by weight in water containing various concentrations of sodium dodecyl sulfate are chosen as the drop phase fluid. The focus of this work is to investigate the effects of concentration of surfactant dissolved in solutions with different viscosities, on physical and geometrical parameters related to drop formation process, such as the drop elongation, minimum neck thickness, formation time, and the drop volume. The formation of satellite drops and the influence of surfactant concentration on their... 

    Estimation of mass transfer during drop formation: New flow expansion model

    , Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; 2004 , Pages 27-34 ; 0791847179 (ISBN); 9780791847176 (ISBN) Javadi, A ; Bastani, D ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Abstract
    Although there is extensive experimental, theoretical and numerical research on dynamics of drop formation in liquid-liquid systems, the evaluation of mass transfer during drop formation is rather complex and there has been little research on that. The various mathematical models developed for this problem are generally based on a solution of the diffusion equation without any allowance for circulation within the drop. This is the main reason for the poor prediction of these models in many cases for which internal convection has an important effect on mass transfer rate. In this paper an attempt was made to define a parameter related to the extent of the convective mixing within the growing... 

    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 Lotfi, M ; 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... 

    Numerical investigation of dynamics of drop motion using lattice boltzmann method

    , Article Journal of Molecular Liquids ; Volume 296 , 2019 ; 01677322 (ISSN) Salehi, M. S ; Afshin, H ; Firoozabadi, B ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Dynamics of a drop under the influence of gravitational force was examined using lattice Boltzmann method and color-gradient model. The term associated with the buoyancy force caused by the density difference between the two phases was modified in the lattice Boltzmann equations and verified in some cases. The motion of n-butyl acetate drops in water was predicted in various deformation regimes. The modeling results were in good agreement with the experimental results, solutions obtained by common CFD methods and semi-empirical correlations. Contrary to the common multiphase models, the behavior of moving drops in oscillating regime was predicted with good accuracy using the present model.... 

    Experimental Investigation on the Accelerated Motion of Newtonian and Non-Newtonian Liquid Drops

    , M.Sc. Thesis Sharif University of Technology Aminzadeh, Milad (Author) ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Supervisor)
    Abstract
    Motion of liquid drops into another fluid is of central importance in a variety of most commonly used industries. Vast applications of emulsions in food and drug industries as well as using of drops in liquid-liquid extraction processes and direct contact heat exchangers are examples in which dynamics of motion of drops play a significant role in operation and efficiency.
    In present study, we consider the accelerated motion of Newtonian and non-Newtonian liquid drops experimentally. In order to find the effect of bulk fluid on the motion of drops, air and water are used as bulk fluid. The experiments have been done on Water, Ethanol, Ethyl acetate, n-Hexane and Toluene as Newtonian and... 

    Toward mechanistic understanding of heavy crude oil/brine interfacial tension: The roles of salinity, temperature and pressure

    , Article Fluid Phase Equilibria ; Vol. 375, issue , August , 2014 , p. 191-200 ; ISSN: 03783812 Moeini, F ; Hemmati-Sarapardeh, A ; Ghazanfari, M. H ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    Abstract
    Injecting low salinity brines is regarded as an enhanced oil recovery (EOR) process through IFT reduction. However, the exact mechanism behind this process is an unsettled and complex issue that has not been well understood yet, especially for heavy crude oil system. Besides, limited information is available regarding the key heavy oil/brine interfacial tension (IFT). The present study aims to investigate the sensitivity of dead heavy crude oil/brine IFT to a wide range of properties/conditions and to reveal the underlying physicochemical mechanisms involved in enhanced oil recovery and IFT reduction by low salinity water injection into heavy oil reservoir. IFT was measured as a function of... 

    Toward mechanistic understanding of heavy crude oil/brine interfacial tension: The roles of salinity, temperature and pressure

    , Article Fluid Phase Equilibria ; Vol. 375, issue , 2014 , Pages 191-200 ; ISSN: 03783812 Moeini, F ; Hemmati-Sarapardeh, A ; Ghazanfari, M. H ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    Abstract
    Injecting low salinity brines is regarded as an enhanced oil recovery (EOR) process through IFT reduction. However, the exact mechanism behind this process is an unsettled and complex issue that has not been well understood yet, especially for heavy crude oil system. Besides, limited information is available regarding the key heavy oil/brine interfacial tension (IFT). The present study aims to investigate the sensitivity of dead heavy crude oil/brine IFT to a wide range of properties/conditions and to reveal the underlying physicochemical mechanisms involved in enhanced oil recovery and IFT reduction by low salinity water injection into heavy oil reservoir. IFT was measured as a function of... 

    Effective partitioning of input domains for ALM algorithm

    , Article 1st Iranian Conference on Pattern Recognition and Image Analysis ; 2013 ; 9781467362047 (ISBN) Afrakoti, I. E. P ; Ghaffari, A ; Shouraki, S. B ; Sharif University of Technology
    2013
    Abstract
    This paper presents a new and simple algorithm for partitioning the input domain for implementation of Active Learning Method (ALM) algorithm. ALM is a pattern-based algorithm for soft computing which uses the Ink Drop Spread (IDS) algorithm as its main engine for feature extraction. In this paper a simple algorithm is introduced with a few computation cost. In order to evaluate the performance of the proposed algorithm, it is applied to two applications, system modeling and pattern recognition. Simulation results show the effectiveness of our algorithm in specifying the appropriate points for dividing the inputs domains