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Formation of traveling liquid bridges between matrix blocks: modeling and simulation
, Article 1st International Petroleum Conference and Exhibition2009 ; 4 May , 2009 ; Masihi, M ; Sharif University of Technology
European Association of Geoscientists and Engineers, EAGE
2009
Abstract
It is widely accepted that under reservoir conditions there exists some degree of block to block interaction that may result in capillary continuity. The formation of liquid bridges causing capillary continuity between blocks will significantly affect ultimate recovery. In this work a mechanistic model with original thought from hydrology for a given steady feeding volumetric flow rate from an upper block (under both gravity and matrix capillary pressure effects) is developed which considers the formation, growth and detachment of pendant liquid droplets perpendicular to the horizontal fracture (assuming to be smooth and parallel walled) between blocks. The length of detached liquid droplet...
Crude oil desalter effluent treatment by a hybrid UF/RO membrane separation process
, Article Desalination ; Volume 238, Issue 1-3 , 2009 , Pages 174-182 ; 00119164 (ISSN) ; Roostaazad, R ; Hesampour, M ; Sharif University of Technology
2009
Abstract
Crude oil desalter effluent from a Tehran oil refinery was treated by a hybrid UF/RO membrane separation process. Ultrafiltration (UF) was used primarily to remove the emulsified oil droplets followed by the removal of total dissolved solids (TDS) via reverse osmosis (RO). The UF membrane was a hydrophilic flat sheet polysulfone ultrafiltration membrane with MWCO of 100 kDa while the RO membrane was a spiral-wound thin-film composite polyamide. Effect of operating conditions such as transmembrane pressure and crossflow velocity were studied in UF pretreatment. The experimental results showed that the UF membrane removed more than 75% of the oil and can be considered as an effective...
Numerical simulation of vortex engine flow field: One phase and two phases
, Article Journal of Thermal Science ; Volume 18, Issue 3 , 2009 , Pages 226-234 ; 10032169 (ISSN) ; Saemi, S. D ; Saidi, M. H ; Sharif University of Technology
2009
Abstract
Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucial importance. Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve higher combustion efficiency. One of the important advantages of designing vortex engine is to reduce the temperature of walls by confining the combustion products in the inner vortex. The scopes of this investigation are to study vortex engine flow field as well as effective parameters on fuel droplet behavior such as droplet diameter, droplet initial velocity and inlet velocity of the flow field. The flow field is simulated using Reynolds Stress Transport Model (RSM). The...
Liquid-liquid coaxial swirl injector performance prediction using general regression neural network
, Article Particle and Particle Systems Characterization ; Volume 25, Issue 5-6 , 2009 , Pages 454-464 ; 09340866 (ISSN) ; Soltani, M. R ; Ashjaee, M ; Morad, M. R ; Sharif University of Technology
2009
Abstract
A general regression neural network technique was applied to design optimization of a liquid-liquid coaxial swirl injector. Phase Doppler Anemometry measurements were used to train the neural network. A general regression neural network was employed to predict droplet velocity and Sauter mean diameter at any axial or radial position for the operating range of a liquid-liquid coaxial swirl injector. The results predicted by neural network agreed satisfactorily with the experimental data. A general performance map of the liquid-liquid coaxial swirl (LLCS) injector was generated by converting the predicted result to actual fuel/oxidizer ratios. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA
Effect of poly (propylene-g-maleic anhydride) on the morphological, rheological, and mechanical properties of PP/HDPE blend
, Article Journal of Thermoplastic Composite Materials ; Volume 22, Issue 5 , 2009 , Pages 519-530 ; 08927057 (ISSN) ; Abdi Valami, M ; Khak, M ; Sharif University of Technology
2009
Abstract
In this study, the morphological, rheological, and mechanical properties of PP/HDPE blend compatibilized with poly (propylene-g-maleic anhydride) were studied. Necessary blends were prepared using a counter current twin-screw extruder. The blend composition ranged from 10 to 50 wt% of dispersed phase (HDPE) and compatibilizer (MAPP) with two Concentration ranges 10, 20 wt% were used for PP/HDPE (80/20) blend with respect to the dispersed phase (HDPE). The results of morphological studies shows a droplet dispersion morphology in the composition to 50wt% HDPE content, which indicates that HDPE forms a dispersed phase and PP forms a continuous phase in these composition region. Addition of the...
New approach in the prediction of RDC liquid-liquid extraction column parameters
, Article Chemical Engineering and Technology ; Volume 31, Issue 7 , 2008 , Pages 971-977 ; 09307516 (ISSN) ; Shahalami, S. M ; Sharif University of Technology
2008
Abstract
The liquid-liquid extraction process is well-known for its complexity and often entails intensive modeling and computational efforts to simulate its dynamic behavior. This paper presents a new application of the Genetic Algorithm (GA) to predict the modeling parameters of a chemical pilot plant involving a rotating disc liquid-liquid extraction contactor (RDC). In this process, the droplet behavior of the dispersed phase has a strong influence on the mass transfer performance of the column. The mass transfer mechanism inside the drops of the dispersed phase was modeled by the Handlos-Baron circulating drop model with consideration of the effect of forward mixing. Using the Genetic Algorithm...
Mass transfer during drop formation on the nozzle: New flow expansion model
, Article AIChE Journal ; Volume 52, Issue 3 , 2006 , Pages 895-910 ; 00011541 (ISSN) ; Bastani, D ; Taeibi Rahni, M ; Sharif University of Technology
2006
Abstract
An attempt was made to introduce a new approach for evaluating mass transfer during drop formation via definition of a parameter related to the extent of the convective mixing within the growing drop. For this purpose it was assumed that the entrance of the dispersed flow into the growing drop from the nozzle is analogous to the entrance of the flow from a smaller channel to a larger one. This transfer mechanism has been dubbed the "flow expansion." A global time-dependent Reynolds number of growing drop (Regd) was defined based on the equivalent diameter of growing drop as a length scale and also on a velocity scale, which is obtained using this flow expansion assumption. The results show...
Effects of non-dimensional parameters on formation and break up of cylindrical droplets
, Article 2004 ASME Heat Transfer/Fluids Engineering Summer Conference, HT/FED 2004, Charlotte, NC, 11 July 2004 through 15 July 2004 ; Volume 2 B , 2004 , Pages 1339-1342 ; Sharafatmand, S ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
The consistent behavior of non-dimensional parameters on the formation and break up of large cylindrical droplets has been studied by direct numerical simulations (DNS). A one-fluid model with a finite difference method and an advanced front tracking scheme was employed to solve unsteady, incompressible, viscous, immiscible, multi-fluid, twodimensional Navier-Stokes equations. This time dependent study allows investigation of evolution of the droplets in different cases. For moderate values of Atwood number (AT), increasing Eotvos number (Eo) explicitly increases the deformation rate in both phenomena. Otherwise, raising the Ohnesorge number (Oh) basically amplifies the viscous effects....
Investigation of the Spray Pattern in the Air Flow Induced by Coaxial Rotors Used for Pesticide Spraying
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor) ; Hejranfar, Kazem (Supervisor)
Abstract
The production of agricultural products is one of the most important human economic activities. The issue of mechanized and optimal use of pesticides is vital for human health and the environment, and the use of helicopters makes this possible. Although spray-based systems in helicopters are one of the most effective ways to produce agricultural products, it is still unclear how droplet movement in aerial spraying is affected by the complex downwash flow created by rotors. Modeling agricultural air spray to identify the spray trend of droplets in the air stream, downwash flows, and consequent vortices has attracted more attention as a result of the development of computational fluid...
Modeling of the Wet Compression System in Transient Behavior of the Industrial Gas Turbine
, Ph.D. Dissertation Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor)
Abstract
In general, the output power of the gas turbines decreases as the ambient temperature increases. One of the ways to deal with such a performance loss is to use a wet compression system, which reduces the air temperature rise throughout the compressor. In this system, the water droplets are injected into the compressor inlet and evaporated throughout the stages. As a result, the work of the compressor decreases, and the power and efficiency of the whole engine increase. Most of the researchers in this field have tried to develop mathematical models to investigate the effects of this system on compressor and gas turbine performance in steady-state conditions. However, it is necessary to...
Simulating of Droplet Formation and Calculation of Interfacial Tension by Microfluidic Method
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor)
Abstract
Emulsions are the intermittent dispersion of liquid droplets that have many applications such as polymerization, dyeing, cosmetics, food industry, etc. Droplets can be created in a variety of ways, but the most important point in emulsification and the greatest efficiency of its applications is when the formed droplets are uniform. In the emulsification process, there is a key parameter called interfacial tension, which affects the behavior of the formed droplets, such as their stability and morphology, and its precise measurement is very effective in the quality control of the mentioned applications. Be. In this research, droplet formation in microfluidic systems due to uniform droplet...
Numerical Simulation to Improve the Efficiency of a Combined Cycle Incorporating a J-Class Gas Turbine Equipped with a Water Fogging System at Its Inlet
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
One way to increase the power and efficiency of the gas turbines is to cool their incoming air. There are different methods to cool down the inlet air. One of the most widely used and suitable method is spraying or fogging the water droplets into the air at the gas turbine air inlet. In this research and for the first time, the effect of fogging system on the performance of a combined cycle incorporated with a J-class gas turbine (M-501J) is investigated using the computational fluid dynamics (CFD). There are so many parameters, which affect the amount of achieved efficiency. A few of them includes the average temperature and humidity at the outlet, the evaporation efficiency of the water...
Simulation, Design, and Fabrication of a Droplet-Based Microfluidic Device to Study The Role of Tumor Microenvironment and Drug Effects on the Behavior of Multicellular Tumor Spheroids
, Ph.D. Dissertation Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
Abstract
Despite the extensive research conducted so far to treat cancer, this disease is still one of the main causes of death worldwide. The results of recent studies reveal the importance of the tumor microenvironment in the growth, proliferation, and invasion of the primary tumor. Most common models in cancer research, such as 2-dimensional in vitro models and xenografts, do not have sufficient ability to mimic the interaction of tumors with human stromal tissue. Therefore, the implementation of 3-dimensional in vitro models with the ability to replicate tumor microenvironments is essential. In this study, a microfluidic platform has been introduced to create parallel models of the tumor...
Simultaneous Impact of Multiple Boiling Droplets on a Molten Phase Change Material as a Direct-Contact Solidification Method
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
Encompassing an interaction between the phase change material (PCM) and the droplets of a heat transfer fluid, the direct contact (DC) method provides a state-of-the-art solution for the meager melting and solidification rates of PCMs. In the DC procedure, when impinging on the molten PCM pool, droplets evaporate, solidifying the portion of the PCM. For the first time, the impact of single and simultaneous double ethanol droplets, having an average diameter of 2.68 mm, on the molten paraffin wax has been scrutinized exhaustively. Experiments have been carried out through high-speed imaging for various Weber numbers ranging from 179 to 464, pool temperatures from 70 to 95°C, and horizontal...
Numerical Investigation of Droplet Generation in a Microfluidic Flow-Focusing Junction Aiming High-Throughput Droplet Generation
, M.Sc. Thesis Sharif University of Technology ; Taghipoor, Mojtaba (Supervisor) ; Hosseini, Vahid (Supervisor)
Abstract
Droplet microfluidic platform generates monodisperse droplets in a desired size through immiscible multiphase flows inside microchannels. Droplets are individual reactor and can be used for bio(chemical) analyses. Also, for materials fabrication, droplet microfluidics offers a versatile platform for generation of nano- or micro-sized particles and microcapsules that are widely used in drug delivery. In addition to the monodispersity, high-throughput generation is also necessary in many applications. Therefore, droplets must be formed in stable regimes (dripping and squeezing) in the highest possible frequency. In this study, the flow-focusing geometry, which is the most common geometry in...
Experimental and Numerical Study of The Production of Alginate Microgels and Cancer Spheroids by Droplet-Based Microfluidic
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
Abstract
Significant advances in biotechnology have led to the emergence of a cost-effective way with less ethical issues to study disease, organ functions, tumors, and their response to drugs besides studying on animals. Microfluidic devices and organ on a chip (tumor on a chip) were introduced to remove those obstacles. Organ on a chip is a powerful tool for studying different types of tissues and simulating diseases, especially cancers, for biological and medical applications. Organ (tumor) on a chip is considered as a smaller scale of the real organ or tumor and it causes to the real-time study of tissues and their functions more accurately. In this study, to fabricate a droplet-based...
Experimental and Numerical Investigation on the Splitting of Microdroplets in Symmetrical and Asymmetrical T Junctions Using Magnetic Fields
, Ph.D. Dissertation Sharif University of Technology ; Shafii, Mohammad Behashad (Supervisor) ; Kazemzadeh Hannani, Siamak (Co-Supervisor)
Abstract
Ferrofluids are used in various fields such as drug delivery systems, heat transfer, biotechnology and separation processes. In this study, the splitting of ferrofluid microdroplets in symmetric and asymmetric T-junctions in the presence of a magnetic field has been investigated numerically and experimentally. These studies have shown that the creation of an asymmetric magnetic field can either affect the phenomenon of ferrofluid microdroplet breakup or the volume of microdroplets that are created after breaking and leaving each branch. Furthermore, more control can be applied to the phenomenon of microdroplet breakup. In the numerical study, the ferrofluid microdroplet breakup at different...
Numerical Study of SARS-CoV-2 Virus Dispersion in Hospital Wards
, M.Sc. Thesis Sharif University of Technology ; Abdekhodaie, Mohammad Jafar (Supervisor)
Abstract
The ongoing Covid-19 pandemic has driven our attention to a simulation of virus dispersion to complete our understanding of airborne transmission. A myriad of studies have shown that respiratory diseases such as MERS, SARS, and COVID-19 can be transmitted by virus-laden droplets released during coughs, sneezing, and normal breathing. To mitigate and prevent the spread of such infectious diseases, investigation of the transmission routes is of great importance. This study has been fueled to harness the CFD tool to simulate the virus-laden droplets dispersion in hospitals inwards. Because of the limitations intertwined with experimental works such as the risk of infection of experimenters, and...
Numerical Modelling and Experimental Validation of Nano Colloid Droplet Formation in the Electrohydrodynamic 3D Printer
, Ph.D. Dissertation Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Supervisor) ; Simchi, Abdolreza (Co-Supervisor) ; Mofrad, Mohammad Reza (Co-Supervisor)
Abstract
The electrohydrodynamic (EHD) 3D printing technology is an Additive Manufacturing (AM) method that can be used in the manufacture of submicron-size structures. Due to the multiphysics dynamics and the multiphase nature of the microdroplet formation in the EHD printers, modeling of this phenomenon is complicated. In this thesis, the formation of a droplet in an EHD printer—under a pulsed electrical field—is simulated using a new numerical model which couples the fluid flow, the electric field distribution and the movement of the electric charges under dynamic and transient conditions. The level-set method is applied to the entire multiphysics domain in order to study the formation of the...
Experimental and Numerical Investigation of Ferrofluid Droplet Formation under Magnetic Field with Biotechnology Application
, Ph.D. Dissertation Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
Droplet-based microfluidics offers a promising tool in engineering and biomedicine such as drug delivery, biochemistry, sample handling in lab-on-a-chip devices, and tissue engineering. These systems provide the droplets manipulation that can be used as reactors without any contamination for medical purposes. Utilizing magnetic force and ferrofluid droplets can help to better control over the droplet formation and manipulation. Considering the importance of this issue and its rich underlying physics, in this dissertation, ferrofluid droplets formation under a time-dependent, non-uniform magnetic field is studied. A Pulse-Width-Modulation signal (PWM) is utilized to apply the time-dependent...