Search for: magnetohydrodynamics
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    Experimental Study of Movement of Mercury Droplets in Micro Channel by Electromagnetic Force

    , M.Sc. Thesis Sharif University of Technology Ardeshir Larijani, Morteza (Author) ; Afshin, Hossein (Supervisor)
    As today's tremendous advance occurred in biotechnology and nanotechnology, the microfluidic devices made a new success that was not possible with the traditional equipments. It was useful in such a way that by using a microliter volume of that fluid, we could have the ability to use it in biologics, medicine, aerospace, cooling electronic systems and medical discovery. One of the main component of fluidic microsystems are micropumps in which they divide into two types. Reciprocating micropumps have been worked by stimulating electromagnetic micropumps which is based on Lorentz law. In this project, we try to investigate the impact of effective parameters in the movement of the mercury mass.... 

    Numerical optimization of three-cavity magneto mercury reciprocating (MMR) micropump

    , Article Engineering Applications of Computational Fluid Mechanics ; Volume 15, Issue 1 , 2021 , Pages 1954-1966 ; 19942060 (ISSN) Mehrabi, A ; Mofakham, A. A ; Shafii, M. B ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    The operation of the three-cavity magneto mercury reciprocating (MMR) micropump, whose prototype were presented in an earlier companion paper, was numerically explored. In the three-cavity MMR micropump, three mercury slugs are moved by a periodic Lorentz force with a phase difference in three separate cavities. A consecutive motion of the slugs in their cavities transfer air from the inlet to the outlet. Two-dimensional OpenFOAM simulations were carried out to explore the influence of electric current excitation phase difference and back-pressure. The numerical simulations predicted the MMR micropump (with no valve) with a phase difference of (Formula presented.) and (Formula presented.)... 

    Numerical study of lorentz force interaction with micro structure in channel flow

    , Article Energies ; Volume 14, Issue 14 , 2021 ; 19961073 (ISSN) Ahmad, S ; Ali, K ; Ahmad, S ; Cai, J ; Sharif University of Technology
    MDPI AG  2021
    The heat transfer Magnetohydrodynamics flows have been potentially used to enhance the thermal characteristics of several systems such as heat exchangers, electromagnetic casting, adjusting blood flow, X-rays, magnetic drug treatment, cooling of nuclear reactors, and magnetic devices for cell separation. Our concern in this article is to numerically investigate the flow of an incompressible Magnetohydrodynamics micropolar fluid with heat transportation through a channel having porous walls. By employing the suitable dimensionless coordinates, the flow model equations are converted into a nonlinear system of dimensionless ordinary differential equations, which are then numerically treated for... 

    Instability in Relativistic Chiral Magnetohydrodynamics

    , M.Sc. Thesis Sharif University of Technology Rahbardar Mojaver, Mehrnoosh (Author) ; Sadooghi, Neda (Supervisor) ; Shokri, Masoud (Co-Supervisor)
    Magnetohydrodynamic is used to study many phenomena. In non-relativistic terms, it can be used to express dynamo theory and to study the evolution of a magnetic field in a conductive fluid medium. In the case of fluid particles having chiral imbalance, the instability associated with this property is observed in the system response to the small perturbation from the equilibrium state. In a relativistic framework, these equations can describe the quark-gluon plasma in the heavy ions collision in a decentralized manner and the nucleus of neutron stars. In many studies, chirality has been considered for such environments. Obtaining the dispersion relation and investigating the response of the... 

    Developing Optimal Model of a Magnetohydrodynamic Generator Based Combined Cycle

    , M.Sc. Thesis Sharif University of Technology Biria, Aisa (Author) ; Saboohi, Yadollah (Supervisor)
    Considering the growing global electricity demand and declining world's fossil fuel resources, developing methods to improve thermal power plants' efficiency and power is of great importance. One method to increase cycle's efficiency is to increase cycle's maximum temperature. MHD generators can be added as a topping cycle to ordinary gas turbine-steam combined cycles, thus increasing cycle's maximum temperature to up to 3000K. In this study a MHD-Gas Turbine-Steam combined cycle has been modeled and optimized. In the high temperatures associated with combustion products plasma, diverse molecular decomposition and ionization processes progress. Therefore, equations of mass, energy, and... 

    Optimization of MHD generator based combined cycle efficiency

    , Article 2005 ASME Power Conference, Chicago, IL, 5 April 2005 through 7 April 2005 ; Volume PART B , 2005 , Pages 1209-1214 ; 0791841820 (ISBN); 9780791841822 (ISBN) Saidi, M. H ; Rezaei, H. D ; Mozafari, A. A ; Dehkordy, A. J ; ASME Power Division ; Sharif University of Technology
    American Society of Mechanical Engineers  2005
    Energy crisis has directed scientific efforts to increase the efficiency of power generation systems. Thermodynamic optimization of MHD (Magneto Hydrodynamic) generator based combined cycles due to their high operating temperatures may seriously reduce exergy destruction and improve the second law efficiency. In this research a combined cycle, comprising of MHD cycle as topping and gas turbine cycle as bottoming cycle has been simulated and analyzed and its pros and cons have been exposed. The first and second law efficiencies have been estimated from the operating pressures and temperatures of the system. To calculate the second law efficiency, the entropy generation of all components of... 

    Simulation of Magnetohydrodynamic Flow in the MWEC Generator Duct Using OpenFOAM Software

    , M.Sc. Thesis Sharif University of Technology Azadi, Ehsan (Author) ; Taghizadeh Manzari, Mehrdad (Supervisor)
    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... 

    Numerical Simulation of Magneto Mercury Reciprocating Micropump

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Ali (Author) ; Shafii, Mohammad Behshad (Supervisor)
    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... 

    Design and Fabrication of Reciprocating Micropumps with Actuated Fluid Slug

    , M.Sc. Thesis Sharif University of Technology Amiri Hezave, Hamid (Author) ; Shafii, Mohammad Behshad (Supervisor)
    Design, fabrication and performance of the reciprocating micropumps with actuated fluid slug have been investigated. In these micropumps, pumping principle is based on reciprocating movement of a fluid slug. The fluid slug must be conductive in magnetohydrodaynamic micropump to be actuated by Lorentz force and have good magnetic properties in ferrofluidic micropumps to be actuated by an external magnetic field.
    On the other hand, a theory is developed in ahead of design and fabrication process to diagnose the critical and the most influential parameters. Magnetohydrodynamic micropumps in 4 distinict design using nozzle-diffuser element, passive ball valve and active mercury valve have... 

    The Effect of Radiation Pressure on Dust and Gas Dynamics in Accretion Disks

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Amir Hossein (Author) ; Rahvar, Sohrab (Supervisor)
    The purpose of this study is to investigate the effect of radiation pressure on accretion disks. The radiation density causes the separation of electrons from ions which leads to the creation of an internal electric dipole. In this study Radiation density is calculated using the Eddington limit. Afterwards radiation pressure is calculated with the use of collisions between photons and electrons in the plasma. Collisions are assumed to happen only between photons and electrons, due to the larger cross section of electrons compared to protons. The mentioned assumption causes the creation of an electric dipole and with it an internal electric field. The separation of the charges is assumed to... 

    On the existence of fast strong and fast weak ionizing detonation waves in magnetohydrodynamics

    , Article Chaos, Solitons and Fractals ; Volume 40, Issue 1 , 2009 , Pages 298-308 ; 09600779 (ISSN) Aghajani, A ; Farjami, Y ; Hesaaraki, M ; Sharif University of Technology
    The existence of structure for ionizing fast-strong and fast-weak detonation waves in magnetohydrodynamics are proved. The reactions are assumed to be one step exothermic reactions with a natural discontinuous reaction rate function. The problem is studied for a general gas, considering some general thermodynamics rules which described by a fairly mild set of hypotheses. The uniqueness and nonuniqueness of structure are also considered. © 2007 Elsevier Ltd. All rights reserved  

    A new wave equation for MHD instabilities in aluminum reduction cells

    , Article TMS 2007 Annual Meeting and Exhibition, Orlando, FL, 25 February 2007 through 1 March 2007 ; 2007 , Pages 345-349 ; 01470809 (ISSN) ; 0873396596 (ISBN); 9780873396592 (ISBN) Kadkhodabeigi, M ; Saboohi, Y ; Sharif University of Technology
    To overcome the problem of magneto hydrodynamic instabilities at the aluminum-cryolite interface in aluminum reduction cells, the use of a simple and efficient model has been suggested. In this paper a new model for evaluation of magneto hydrodynamic instabilities in aluminum reduction cells is proposed. This model is in the form of a wave equation for interfacial oscillations and is constructed based on Shallow Water approximation and linear stability analysis. In this model two terms for linear friction in each molten layer of aluminum and cryolite has been considered and also Lorentz forces in cryolite layer have not been neglected. By accounting of these additional terms in our model,... 

    Second law analysis of an infinitely segmented magnetohydrodynamic generator

    , Article Journal of Magnetism and Magnetic Materials ; Volume 426 , 2017 , Pages 294-301 ; 03048853 (ISSN) Arash, A ; Saidi, M. H ; Najafi, M ; Sharif University of Technology
    Elsevier B.V  2017
    The performance of an infinitely segmented magnetohydrodynamic generator is analyzed using the second law of thermodynamics entropy generation criterion. The exact analytical solution of the velocity and temperature fields are provided by applying the modified Hartmann flow model, taking into account the occurrence of the Hall effect in the considered generator. Contributions of heat transfer, fluid friction, and ohmic dissipation to the destruction of useful available work are found, and the nature of irreversibilities in the considered generator is determined. In addition, the electrical isotropic efficiency scheme is used to evaluate the generator performance. Finally, the implication of... 

    Numerical Simulation of Compressible Magnetohydrodynamic Flow Using Spectral Difference Method on Quadrilateral Grids

    , M.Sc. Thesis Sharif University of Technology Kafian, Hesam (Author) ; Hejranfar, Kazem (Supervisor)
    In the present work, the numerical solution of 2D inviscid compressible Magneto-hydrodynamic flow is performed by using the spectral difference (SD) method on quadrilateral grids. In this numerical method, similar to the discontinuous Galerkin (DG) and spectral volume (SV) methods, the concept of the discontinuous and high-order local representations is used to achieve conservation property and high-order accuracy. In the SD method, the test function or the surface integral is not involved and thus it has a simpler formulation than the DG and SV methods. In this numerical method, two sets of structured points, namely unknown points and flux points, are defined in each cell to support the... 

    System Modeling of Hydrogen Combustion And The Formation Of Plasma And Its Application In MHD Power Plant

    , M.Sc. Thesis Sharif University of Technology Hassan Moradyan, Hossein (Author) ; Sobbohi, Yadollah (Supervisor)
    The purpose of this project is modeling and solving equation of an open cycle system based on MHD generator in order to achiving geometrical properties of generator shuch as length and cross sections of channel and extractable electrical power. In this work hydrogen is used as initial fuel and it’s combustion product near oxygen as working fluid in an open cycle system concluding of combustion chamber, convergence nozzle, farady generator with separated electrod’s and constant mach number and also diffuser. Motion of fluid is considered one dimentional and direction of magnetic field with magnitude of 2 tesla is assumed to be perpendicular to motion and electrical current directs. For... 

    Numerical Simulation of 2D Inviscid Compressible Magnetohydrodynamic Flows by Spectal Difference Method

    , M.Sc. Thesis Sharif University of Technology Kharratyan, Mahdi (Author) ; Hejranfar, Kazem (Supervisor)
    In the present study, the numerical solution of 2D inviscid compressible ideal magnetohydrodynamic (MHD) flows by using the spectral difference (SD) method on unstructured meshes is performed. The SD method combines the most desirable features of structured and unstructured grid methods to have computational efficiency and geometric flexibility to accurately compute flow over complex geometries. In the SD method, two sets of structured points, namely “unknown points” and “flux points”, are defined in each cell to support the reconstruction of given order of accuracy. The differential form of the conservation laws is satisfied at nodal unknown points while the flux derivatives expressed in... 

    Fabrication and Experimental Investigation of Rotary Agnetohydrodynamic Micropump

    , M.Sc. Thesis Sharif University of Technology Esmaily Moghaddam, Mahdi (Author) ; Behshad Shafii, Mohammad (Supervisor)
    Considering the advantages and disadvantages of reported micropumps, we aimed to introduce a novel idea to diminish the disadvantages and promote the advantages of Magnetohydrodynamic (MHD) micropumps. This novel idea operates based on a mercury slug rotation in a circular microchannel. This cyclic motion of the mercury slug which is similar to a piston, push the fluid in the microchannel and pump the flow. However, to bring this idea into the practice, it must be integrated with a specific valve. Fluid has not to go through this specific valve. In contrary, mercury slug has to pass across this valve. These two specifications must be considered during the design process of the valve. On the... 

    Numerical Simulation of Rotary Magnetohydrodynamic Micropump

    , M.Sc. Thesis Sharif University of Technology Abdollahi Mofakham, Amir (Author) ; Shafii, Mohammad Behshad (Supervisor)
    First by reviewing some built micropumps, the importance of rotary magnetohydrodynamic micropump has been highlighted. Then some information about the performance and rules applied to these specific micropumps has been provided. Based on the research, the necessity of using transient flow relations for analyzing the procedure of these micropumps would become crucial. The next step would be extracting the information out of dimensionlessrelations of magnetohydrodynamic theory and dimension less equations of momentum in transientsingle-phase fluid flow which is moved by theoverall Lorentzforce in between 2 parallel surfaces. It would be done in two state of using constantcurrent source and... 

    Evolution of Electromagnetic Fields in a Plasma of Quarks and Gluons

    , Ph.D. Dissertation Sharif University of Technology Shokri, Masoud (Author) ; Sadooghi, Neda (Supervisor)
    In heavy ion collisions, extremely large electromagnetic fields are produced by fast-moving charged nucleons. They are sufficiently large to affect the low energy QCD processes and thus produce observable effects, whose occurrence is, however, directly related to the lifetime of these fields. In the present dissertation, the evolution of electromagnetic fields is studied in a plasma of quarks and gluons, by analytically solving the equations of relativistic magnetohydrodynamics (RMHD). The onideal Bjorken RMHD is solved by introducing the method of nonconserved charges. Assuming an electromagnetic force-free condition, the electric and magnetic fields are found to be either parallel or... 

    Optimal Design of Induction MHD Generator for Electrical Power Generation from Exhaust of the Gas Turbine Power Plants

    , M.Sc. Thesis Sharif University of Technology Barzegar, Iran (Author) ; Boroushaki, Mehrdad (Supervisor)
    Today, due to increasing electricity consumption and demand, the use of conventional systems such as thermal, hydro and nuclear power plants is not enough to convert energy. Over the past century, scientists have sought to discover new technologies for exploiting different forms of energy and converting them into high-efficiency electrical energy. One of these ways is to use the phenomenon of magnetohydrodynamics (magnetic fluid dynamics) to convert thermal energy directly into electrical energy. Magnetohydrodynamics is a theoretical field that studies the dynamics of fluids with electrical conductivity. Induction magneto-hydrodynamic generators use ionized hot plasma (a quasi-neutral gas of...