Search for: effect-of-magnetic-field
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    Effect of magnetic field on internal forced convection of ferrofluid flow in porous media

    , Article Experimental Heat Transfer ; Volume 29, Issue 1 , 2016 , Pages 1-16 ; 08916152 (ISSN) Sadrhosseini, H ; Sehat, A ; Shafii, M. B ; Sharif University of Technology
    Taylor and Francis Ltd 
    Enhancement of heat transfer is investigated in an experimental study of ferrofluid flow in a tube subjected to a constant and uniform heat flux on its wall, filled with permeable material under the effect of magnetic field. Effect of ferrofluid volume fraction, Reynolds number, and different frequencies of various magnetic field modes on heat transfer is examined by measuring the temperature on the wall. Using ferrofluid under the effect of magnetic field improves the heat transfer, and porous media makes the temperature distribution more uniform. Volumetric percentage of nano-particles has the greatest effect on the heat transfer  

    Enhancement of pool boiling heat transfer using ferromagnetic beads in a variable magnetic field

    , Article Applied Thermal Engineering ; Volume 164 , 2020 Rahmati, P ; Ebrahimi Dehshali, M ; Hakkaki Fard, A ; Sharif University of Technology
    Elsevier Ltd  2020
    The pool boiling is one of the heat transfer mechanisms used in cooling systems. Using an external force to improve the efficiency of thermo-fluid systems is among the most effective approaches, and also highly applicable in enhancing heat transfer. In this study, the pool boiling of water, as the working fluid, in the presence of a variable magnetic field, is studied. To this end, ferromagnetic beads were placed on the boiling surface, and the effect of their movements due to a variable magnetic field was observed and measured. The number of beads was selected such that they would cover 1/3, 1/2 and 2/3 of the surface in different cases and the magnetic field was controlled by altering... 

    Tuning of random lasers by means of external magnetic fields based on the Voigt effect

    , Article Optics and Laser Technology ; Volume 47 , April , 2013 , Pages 121-126 ; 00303992 (ISSN) Ghasempour Ardakani, A ; Mahdavi, S. M ; Bahrampour, A. R ; Sharif University of Technology
    It has been proposed that emission spectrum of random lasers with magnetically active semiconductor constituents can be made tunable by external magnetic fields. By employing the FDTD method, the spectral intensity and spatial distribution of electric field are calculated in the presence of an external magnetic field. It is numerically shown that due to the magneto-optical Voigt effect, the emission spectrum of a semiconductor-based random laser can be made tunable by adjusting the external magnetic field. The effect of magnetic field on the localization length of the laser modes is investigated. It is also shown that the spatial distribution of electric field exhibited remarkable... 

    Effect of magnetic field on thermal conductivity and viscosity of a magnetic nanofluid loaded with carbon nanotubes

    , Article Journal of Mechanical Science and Technology ; Volume 30, Issue 2 , 2016 , Pages 809-815 ; 1738494X (ISSN) Shahsavar, A ; Salim Pour, M. R ; Saghafian, M ; Shafii, M. B ; Sharif University of Technology
    Korean Society of Mechanical Engineers 
    The present work examines experimentally the effect of magnetic field on the viscosity and thermal conductivity of a hybrid nanofluid containing tetramethylammonium hydroxide (TMAH) coated Fe3O4 nanoparticles and Gum arabic (GA) coated carbon nanotubes (CNTs). The hybrid nanofluid was prepared by using ultrasonic dispersion method. Magnetic field was created by a pair of spaced apart magnet plates. The effect of temperature on the time variation of thermal conductivity under applied magnetic field was also investigated. According to the results of this study, viscosity of the hybrid nanofluid increases with the strength of magnetic field, while it decreases with the increase of temperature.... 

    Hydrodynamics of fingering instability in the presence of a magnetic field

    , Article Fluid Dynamics Research ; Volume 48, Issue 5 , 2016 ; 01695983 (ISSN) Mostaghimi, P ; Ashouri, M ; Ebrahimi, B ; Sharif University of Technology
    Institute of Physics Publishing 
    The hydrodynamics of two immiscible fluids in a rectangular Hele-Shaw cell under the influence of a magnetic field is studied, both theoretically and numerically. A linear stability analysis is conducted to determine the effect of magnetic fields on the formation of viscous fingers. As a result, an analytical solution is found to calculate the growth rate of perturbations. For numerical simulation of the two-phase flow, the interfacial tension is treated as a body force using the continuum surface force model and the interface tracking is performed by the volume of fluid method. The variations of the width and growth rate of fingers in an unstable displacement versus Hartmann number, a... 

    Effect of non-uniform magnetic field on heat transfer of swirling ferrofluid flow inside tube with twisted tapes

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 117 , 2017 , Pages 70-79 ; 02552701 (ISSN) Mokhtari, M ; Hariri, S ; Barzegar Gerdroodbary, M ; Yeganeh, R ; Sharif University of Technology
    In this article, a three-dimensional numerical simulation is performed to investigate the effect of magnetic field on the heat transfer of ferrofluid inside a tube which is equipped with twisted tape. This work comprehensively focused on the flow feature and temperature distribution of ferrofluid in presence of non-uniform magnetic field while ferrofluid swirled inside a tube with twisted tape. In this study, it is assumed that the ferrofluid is single phase and laminar and constant heat flux is applied on the outside of the tube. The magnetic field is established by wire in parallel direction with the axis of the tube. The base fluid is water with 0.86 Vol% Nano particles (Fe3O4). The... 

    Effect of transverse and parallel magnetic fields on thermal and thermo-hydraulic performances of ferro-nanofluid flow in trapezoidal microchannel heat sink

    , Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 31, Issue 7 , 2021 , Pages 2089-2111 ; 09615539 (ISSN) Sepehrnia, M ; Khorasanizadeh, H ; Shafii, M. B ; Sharif University of Technology
    Emerald Group Holdings Ltd  2021
    Purpose: This paper aims to study the thermal and thermo-hydraulic performances of ferro-nanofluid flow in a three-dimensional trapezoidal microchannel heat sink (TMCHS) under uniform heat flux and magnetic fields. Design/methodology/approach: To investigate the effect of direction of Lorentz force the magnetic field has been applied: transversely in the x direction (Case I);transversely in the y direction (Case II); and parallel in the z direction (Case III). The three-dimensional governing equations with the associated boundary conditions for ferro-nanofluid flow and heat transfer have been solved by using an element-based finite volume method. The coupled algorithm has been used to solve...