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Sheikholeslami M.,University of Mazandaran | Sheikholeslami M.,Babol Noshirvani University of Technology | Hatami M.,Islamic Azad University at Esfarayen | Ganji D.D.,Babol Noshirvani University of Technology
Journal of Molecular Liquids | Year: 2014

In this paper the magnetohydrodynamic (MHD) nanofluid flow and heat transfer between two horizontal plates in a rotating system is analyzed. The lower plate is a stretching sheet and the upper one is a solid permeable plate. The basic partial differential equations are reduced to ordinary differential equations which are solved numerically using the fourth-order Runge-Kutta method. Different types of nanoparticles such as copper, silver, alumina and titanium oxide with water as their base fluid have been considered. Velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number are determined numerically. The influence of pertinent parameters such as nanofluid volume fraction, magnetic parameter, wall injection/suction parameter, viscosity parameter and rotation parameter on the flow and heat transfer characteristics is discussed. The results indicate that, for both suction and injection the Nusselt number has a direct relationship with the nanoparticle volume fraction. The type of nanofluid is a key factor for heat transfer enhancement. The highest values are obtained when titanium oxide is used as a nanoparticle. Also it can be found that the Nusselt number decreases with the increase of the magnetic parameter due to the presence of Lorentz forces. © 2013 Elsevier B.V. Source


Hatami M.,Islamic Azad University at Esfarayen | Hatami M.,Babol Noshirvani University of Technology | Ganji D.D.,Babol Noshirvani University of Technology
International Journal of Refrigeration | Year: 2014

Temperature distribution equation and refrigeration efficiency for fully wet circular porous fins with variable sections are introduced in this study by a new modified wet fin parameter presented by Sharqawy and Zubair. This parameter can be calculated without knowing the fin tip condition by considering the temperature and humidity ratio differences for the driving forces of heat and mass transfer, respectively. It's assumed that heat and mass convective coefficients vary with fin temperature and heat transfer through porous media is simulated using passage velocity from the Darcy's model. After presenting the governing equation, Least Square Method (LSM) and fourth order Runge-Kutta method (NUM) are applied for predicting the temperature distribution in the sample aluminum porous fins. After that, effects of porosity, Darcy number, Rayleigh number, Lewis number and etc. on fin efficiency are examined. As a main outcome, for reaching to high values of fin efficiency, rectangular fin should be used instead of convex and triangular sections. © 2013 Elsevier Ltd and IIR. All rights reserved. Source


Hatami M.,Islamic Azad University at Esfarayen | Ganji D.D.,Babol Noshirvani University of Technology
Powder Technology | Year: 2014

In this letter, the equation of a particle's motion on a rotating parabolic surface is introduced through Lagrange equations and is solved by Multi-step Differential Transformation Method (Ms-DTM). As a main outcome, it is shown that this method gives approximations of a high degree of accuracy and least computational effort for studying particle motion on rotating parabolic surfaces compared to previous analytical methods. Also, position trajectory of the particle, r(t), and its phase planes are depicted in the current study for different constant numbers. © 2014 Elsevier B.V. Source


Hatami M.,Islamic Azad University at Esfarayen | Hatami M.,University of Mazandaran | Hatami J.,Semnan University of Medical Sciences | Ganji D.D.,University of Mazandaran
Computer Methods and Programs in Biomedicine | Year: 2014

In this paper, heat transfer and flow analysis for a non-Newtonian third grade nanofluid flow in porous medium of a hollow vessel in presence of magnetic field are simulated analytically and numerically. Blood is considered as the base third grade non-Newtonian fluid and gold (Au) as nanoparticles are added to it. The viscosity of nanofluid is considered a function of temperature as Vogel's model. Least Square Method (LSM), Galerkin method (GM) and fourth-order Runge-Kutta numerical method (NUM) are used to solve the present problem. The influences of the some physical parameters such as Brownian motion and thermophoresis parameters on non-dimensional velocity and temperature profiles are considered. The results show that increasing the thermophoresis parameter (Nt) caused an increase in temperature values in whole domain and an increase in nanoparticles concentration just near the inner wall of vessel. Furthermore by increasing the MHD parameter, velocity profiles decreased due to magnetic field effect. © 2013 Elsevier Ireland Ltd. Source


Hatami M.,Islamic Azad University at Esfarayen | Ganji D.D.,Babol Noshirvani University of Technology
Ceramics International | Year: 2014

In this study, heat transfer and temperature distribution equations for longitudinal convective-radiative porous fins are presented. It is assumed that the thickness of fins varies with length, so four different shapes (rectangular, convex, triangular and exponential) are considered. Temperature-dependent heat generation, convection and radiation are considered and heat transfer through porous media is simulated using passage velocity from Darcy's model. After deriving equation for all geometries, the Least Square Method (LSM) and fourth order Runge-Kutta method (NUM) are applied for predicting the temperature distribution in the porous fins. The selected ceramic porous materials are Al, SiC, and Si3N4. Effects of porosity, Darcy number, Rayleigh number, etc. on transferred heat are examined. As a main outcome, exponential section fin with Si3N4 material has the most amount of transferred heat among other shapes and materials. © 2013 Elsevier Ltd and Techna Group S.r.l.All rights reserved. Source

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