Sharif Digital Repository

In this work, the cone-jet mode of electrospray is simulated by a two phase solver in OpenFoam software. For this aim firstly, breakup of a liquid jet is examined without applying any electric potential to the injecting capillary and results are compared with other works to evaluate the two phase solver. Next with applying electric potential, the whole evolution of cone-jet in time is simulated. One of the most important issues in this mode is the minimum potential that needs to form a stable cone-jet in different flow rates. These minimum voltages are obtained in various flow rates and compared with other experimental and computational works. Result shows that with increasing flow rate the... 

In this investigation Magneto Mercury Reciprocating Micrpump (MMRM) the combination of Magneto-Hydrodynamic and Reciprocating micropumps has been analyzed. To achieve the analytical and numerical solution of one-tank and three-tank MMRM, the momentum, continuity, volume fraction and magnetohydrodynamic equations have been presented. The dimensionless analytical solution of one-phase and two-phase three dimensional MHD flow in the condition of using constant current and potential electrical source, has been offered.
The boundary between mercury and air has been tracked via VOF method in OpenFOAM software. VOF equation has been solved by explicit method with variable time step and maximum... 

Heterogeneity is the major cause of the uneven acid distribution in carbonate acidizing. Traditional acidizing involves the injection of mineral acids, such as hydrochloric acid into the formation, which the bulk of the acidic solution permeates into the high-permeable layers and the low-permeability layers remain unreacted. So far, many chemical and mechanical techniques have been used to avoid the uneven distribution of acid. Using surfactant-based viscoelastic acids is one of the effective chemical method to divert acid to low-permeable zones. The unique feature of these acids is increasing viscosity of acidic solution as the pH increases. In this study, a two-scale continuum model... 

In this study, the numerical simulation of turbulent flow using Open Source software OpenFOAM, The impact of air flow around the high-rise buildings and classification based on the height and arrangement of the buildings has been against the flow. Numerical method used, the finite volume method uses a piso algorithm, Navier-Stokes equations are solved and the speed and pressure can be obtained. Large Eddy Simulation model is a simulation model used in this software. In general tall buildings against wind loads has three types of move, move along the wind, prependicular along the wind and the twisting motion that occurs at the same time, they are, but, due to the variable nature and... 

Detecting of coherent structures in bidirectional vortex combustion chamber is the original aim of this project. For this aim a numerical simulation is performed by using OpenFOAM, open-source CFD software. Also influence of fuel nozzle places in formation of coherent structures is analyzed. Effects of combustion in these structures and differences in cold and hot flows are analyzed too. There are papers that present influence of coherent structures in vortex burners and other applications, but based on reviews that are performed in this work, it seems that influence of coherent structures have not seen in bidirectional vortex chambers. So it can be one of innovations of this work. Swirl... 

Numerical investigation of flow field and determination of velocity components in swirl flow are novel and important subjects in combustion chamber of swirl flow. The exact understanding of vortex phenomena and flow structures in vortex engine results in better design and control in terms of stability, geometry, cooling, and combustion efficiency. Although, numerical approaches are computationally complex, they are worthwhile and efficient. The aim of this work is to study the velocity field in a bidirectional swirl flow within the combustion chamber using numerical approaches. The investigation of flow field has been performed in the cold chamber. Four different models (RSM and LES) have... 

Magnetohydrodynamic (MHD) flow is concerned with the interaction between the magnetic field and electrically conducting fluid flow. In this investigation, the MHD flow in the duct of magnetohydrodynamic wave energy conversion (MWEC) generator was simulated by use of OpenFOAM software. In the MWEC generator the reciprocating motion of ocean waves lead to electrically conducting fluid flow in the duct of this generator. By applying magnetic field perpendicular to this flow, electric current generate in the fluid. This generator has a higher efficiency compared with other ocean wave energy conversion generators. Firstly, to evaluate accuracy and performance of mhdFOAM code of OpenFOAM, three... 

Cavitation is a phenomenon that liquid turns into vapor in constant temperature. Cavitation has been assorted into variant models that cloud cavitation is one of them. Cloud cavitation has an unsteady regime which shed cavity into its surrounding that contribute to oscillations, shocks and efficiency reduction of hydrodynamic machines. Triping of boundary layer for enhancing turbulent intensity is a method for preventing cloud cavitation. In this thesis firstly we have simulated boundary layer on 2D NACA0015 hydrofoil with 8 degree attack angle and no cav( ) condition. According to laminar separation location, we have placed some artificial cavity generator(ACG) with size of boundary layer... 

Acidizing is one of the widely used practices of formation damage remediation. The success of this rather expensive job depends on the precise design and operation. Though, improper execution of an acid job, not only does not improve the formation damage but also can contribute to even more damage itself. For this purpose, it is critically important to thoroughly design an acidizing job conducting extensive lab experiments and utilizing numerical tools before operation in order for a successful acidizing. Unlike, carbonate acidizing, the chemistry of sandstone acidizing is very complex and challenging because of the wide variety of minerals and aqueous species present in the system. Hence, a... 

Acidizing operation is performed in oil and gas reservoirs with the aim of overcoming formation damages, increasing permeability and reducing skin factor. In carbonate reservoir, the hydrochloric acid increases the permeability of the areas around the well to a more than its initial value by dissolving part of the formation minerals. Considering that most of Iran's oil and gas reservoirs are in the category of carbonate reservoirs, it is important to study the reaction kinetics of carbonate minerals and acids used in acidizing operation. The complex and multifactorial nature of the acidizing operation in the reservoirs has made it very difficult to design a successful and optimal operation.... 

Injection of acid into the carbonate rock dissolves the rock, and the porous medium is constantly changing. As a result, the boundaries between the acid and the porous medium, which are in fact the interface between the solid phase and the liquid phase, are constantly changing. Therefore, on the issue of acid injection into carbonate rock, we are facing dynamic boundary conditions. Also, due to the simultaneous solution of transfer and reaction phenomena, modeling acid injection into carbonate rock faces many challenges.In such problems, the ALE method, which is a combination of the best features of the Lagrangian method and the Eulerian method, offers a very precise solution and is used as... 

Today, due to the decline of drinkable water, many desalination plants have been established and operated around the world. Disposal of these brines, which have higher density and temperature than receiving water, causes many environmental impacts. Industrial power plants discharge these effluents into the seawater body mostly as submerged jets due to their higher effectiveness. Many experimental researches have been done on the negative and positive buoyant jet that discharged form desalination plants. But a few numerical studies have been done with investigating the full Navior-Stokes equations and they have been flawed in modeling. For example, some of these models have been able to... 

Today, acidizing is one of the most important methods for stimulation and increasing the productivity of oil and gas wells. In Iran and other oil-rich countries, a large amount of money is invested every year in acidizing operations. Due to complex nature of acidizing of an oil formation, it’s very difficult to design an optimized and successful operation. Therefore, many research projects have been performed for understanding the physics of the dissolution of reservoir rock by acid and the behavior of wormholes and secondary reactions. The most important prerequisite of these researches is the perfect knowledge of acid and mineral reaction kinetics. One of the most common experiments to... 

In the present work, large eddy simulation approach was employed to investigate flows such as backward facing step and internal channel flow, using Smagorinsky and explicit algebraic subgrid-scale models (EASSM) in OpenFOAM software. For this purpose, an explicit algebraic subgrid-scale model was added to OpenFOAM. Coupling pressure and velocity fields were applied to the PISO-SIMPLE (PIMPLE) algorithm. The focus of the present study was to assess various subgrid scale models, in order to predict the behavior of several flows, as well as their extensive numerical study. The results were compared to available experimental data showning that the EASSM results were more accurate than... 

In this study, the factors affecting cavitation in the crest of an ogee spillway were investigated. One of the factors affecting the occurrence of cavitation on the ogee crest is the ratio of the head to the design head. As the head ratio increases, the probability of cavitation on the crest increases. The value of the head is also an effective parameter for the occurrence of cavitation. The spillway crest curve is also one of the factors affecting the occurrence of cavitation on the ogee-crested spillways. In this study, the ogee crested spillway that consists of three circular arcs upstream has been investigated. 5 different head ratios have been used. For this study, OpenFOAM software,... 

A large number of desalination plants have been established to overcome the drinkable water scarcity in the world. These plants produce saline water as effluent, which is often discharged into local sea water. One of the applicable methods to dispose these kinds of effluents is to install an inclined nozzle below the water’s surface. Hence, an inclined negatively buoyant jet (INBJ) forms which is often fully turbulent due to the high discharge velocity. Local environmental characteristics affect the dynamics and mixing behavior of INBJs. One of these characteristics is the sea bed slope, on which the present study has been focused. Large eddy simulations (LES) are performed in the present... 

Boundary layer control has long been and still is considered to reduce drag. In this research, the effect of quasi-spherical structures on the control of boundary layer is investigated. First, flow over a NACA0015 airfoil was investigated. Then, flow over the same airfoil with quasi-spherical bumps on its upper surface was numerically simulated and the result of these two situations were compared. The dimensions and numbers of the bumps in longitudinal and lateral directions (different case studies) were chosen using trial and error. The three-dimensional, incompressible, and turbulent flow governing equations were numerically solved, using FVM and the OpenFOAM software. To get preliminary... 

Over the course of past decade, air pollution has been placed among the top issues chocking capital Tehran. Stationary source of air pollution is among the most important, but, less treated facors. On the year, 2014, Tehran’s air quality company addressed a number of projects in this very field could gain further governmental supports. This announcement could be a sign, showing the importance of this research. These researches in fact, have the potentioal to increase the authority’s decision making abilities in critical situations. As the models prognosticates future with acceptble accuracy, it leads to highly efficient dicissions. The results could also be used in demographic studies as... 

Low-salinity waterflooding (LSWF) is a promising EOR approach that decreases the oil-wetness of reservoir rocks, hence increasing the recovery factor. Despite the importance of the pore-geometry on the performance of LSWF, especially in 3D simulations being affected by corner-flow and roughness, it is not yet investigated, thus in this thesis we aim at studying the aforementioned effects on LSWF. According to the preceding studies, during the drainage phase, the brines in the corners of pores cannot be displaced by oil because of requiring very high capillary pressure; thereby rendering a mixed-wet system. Hence considering this type of wettability is necessary for two-phase flow... 

Mass or large-scale storage of hydrogen, as a clean source of energy, should be conducted in underground formations in order to be used as a reliable energy source at the peak of consumption. In this regard, underground formations such as aquifers and depleted hydrocarbon reservoirs are the most favorable and secured media for hydrogen storage. However, detailed understanding of the flow dynamics of hydrogen-water in these media is critical to maximize hydrogen storage and recovery and tackle the existing uncertainities which exist in the flow functions. To fill this gap, this research aims at a detailed pore-scale investigation of the effect of flow regime, hydrogen compressibility, and...