Hartmann number

About: Hartmann number is a research topic. Over the lifetime, 2593 publications have been published within this topic receiving 61342 citations.

Effect of Induced Magnetic Field on Natural Convection in Vertical Concentric Annuli Heated/Cooled Asymmetrically

Abstract: In the present paper, the fully developed laminar free convective flow of a viscous incompressible and electrically conducting fluid between two concentric vertical cylinders is considered in the presence of a radial magnetic field. The induced magnetic field produced by the motion of an electrically conducting fluid is taken into account. The expressions for the temperature, velocity, induced magnetic field, induced current density, skin-friction and Nusselt number are obtained in a closed form under more general boundary conditions for the induced magnetic field. The influence of the Hartmann number and buoyancy force distribution parameter on the fluid velocity, induced magnetic field and induced current density have been analyzed by using the graphs while the values of the skin-friction, Nusselt number, induced current flux and mass flux are given in the tabular form. It is observed that the fluid velocity and induced magnetic field are rapidly decreasing with increase in the value of Hartmann number in the case when one of the cylinders is conducting compared with the case when both cylinders are non-conducting. The effect of the induced magnetic field is to increase the velocity profiles in comparison to the case of neglecting the induced magnetic field. The buoyancy force distribution parameter has tendency to increase the fluid velocity, induced magnetic field, temperature field and induced current flux.

Heat transfer to MHD oscillatory dusty fluid flow in a channel filled with a porous medium

Abstract: In this paper, we examine the combined effects of thermal radiation, buoyancy force and magnetic field on oscillatory flow of a conducting optically thin dusty fluid through a vertical channel filled with a saturated porous medium. The governing partial differential equations are obtained and solved analytically by variable separable method. Numerical results depicting the effects of various embedded parameters like radiation number, Hartmann number and Grashof number on dusty fluid velocity profiles, temperature profiles, Nusselt number and skin friction coefficient are presented graphically and discussed qualitatively.

MHD turbulence in a channel with spanwise magnetic field

Abstract: The effect of a uniform spanwise magnetic field on a turbulent channel flow is investigated for the case of low magnetic Reynolds number. DNS and LES computations are performed for two values of the hydrodynamic Reynolds number (10^4 and 2\times 10^4) and the Hartmann number varying in a wide range. It is shown that the main effect of the magnetic field is the suppression of turbulent velocity fluctuations and momentum transfer in the wall-normal direction. This leads to drag reduction and transformation of the mean flow profile. The centerline velocity grows, the mean velocity gradients near the wall decrease, and the typical horizontal dimensions of the coherent structures enlarge upon increasing the Hartmann number. Comparison between LES and DNS results shows that the dynamic Smagorinsky model accurately reproduces the flow transformation.

Convective heat transfer of ferrofluid in a lid-driven cavity with a heat-conducting solid backward step under the effect of a variable magnetic field

Abstract: The effect of variable magnetic field on the mixed convective flow of a ferrofluid within a lid-driven cavity has been analyzed numerically. A heat-conducting solid block is located in the bottom part of the cavity. Governing partial differential equations have been formulated taking into account that the magnetic source is a point source located over the moving lid. Analysis has been performed for a wide range of Hartmann number, nanoparticles volume fraction, and magnetic number. It has been found that the growth of the magnetic number leads to the heat transfer enhancement.

Numerical simulation for heat transfer intensification of nanofluid in a porous curved enclosure considering shape effect of Fe3O4 nanoparticles

Abstract: In this paper, influence of external magnetic field and thermal radiation on heat transfer intensification of nanofluid in a porous curved enclosure is simulated. Magnetic field and shape factor effects on nanofluid properties are taken into account. Final equations are obtained by means of vorticity stream function formulation and they are solved via Control volume based finite element method. Isotherms and streamlines are shown for various values of Darcy number, Fe 3 O 4 -water nanofluid volume fraction, radiation parameter, Hartmann number and Rayleigh number. Results indicate that maximum Nusselt number is obtained for Platelet shaped nanoparticles. Heat transfer rate augments with rise of permeability of porous media and Rayleigh number and opposite trend is observed for Hartmann number. Besides, it can be found that velocity of nanofluid decreases with increase of Lorentz forces.