Sharif Digital Repository

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.... 

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... 

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... 

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... 

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, 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 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... 

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... 

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... 

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... 

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... 

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...