Influence of a horizontal magnetic field on the natural convection of paramagnetic fluid in a cube heated and cooled from two vertical side walls

The effect of the direction of external horizontal magnetic fields on the linear stability of natural convection of liquid metal in an infinitely long vertical rectangular enclosure is numerically studied. A vertical side wall is heated and the opposing vertical wall is cooled both isothermally, whereas the other two vertical walls are adiabatic. A uniform horizontal magnetic field is applied either in the direction parallel or perpendicular to the temperature gradient. In this study, the height of the enclosure is so long as to neglect the top and bottom effects where returning flow takes place, and thus the basic flow is assumed to be a parallel flow and the temperature field is in heat conduction state. The Prandtl number is limited to the value of 0.025 and horizontal cross-section is square. The natural convection is monotonously stabilized as increase in the Hartmann number when the applied magnetic field is parallel to the temperature gradient. However, when the applied magnetic field is perpendicular to the temperature gradient, it is once destabilized at a certain low Hartmann number, but it is stabilized at high Hartmann numbers.

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Effect of magnetic field on nanofluid free convection in Conical Partially Annular Space

MATEC Web of Conferences ◽

10.1051/matecconf/202033001005 ◽

2020 ◽

Vol 330 ◽

pp. 01005

Author(s):

Abderrahmane AISSA ◽

Mohamed Amine MEDEBBER ◽

Khaled Al-Farhany ◽

Mohammed SAHNOUN ◽

Ali Khaleel Kareem ◽

...

Keyword(s):

Magnetic Field ◽

Hartmann Number ◽

Volume Fraction ◽

Boussinesq Approximation ◽

Simulation Software ◽

Comsol Multiphysics ◽

Governing Equations ◽

Element Analysis ◽

Vertical Side ◽

Side Walls

Natural convection of a magneto hydrodynamic nanofluid in a porous cavity in the presence of a magnetic field is investigated. The two vertical side walls are held isothermally at temperatures Th and Tc, while the horizontal walls of the outer cone are adiabatic. The governing equations obtained with the Boussinesq approximation are solved using Comsol Multiphysics finite element analysis and simulation software. Impact of Rayleigh number (Ra), Hartmann number (Ha) and nanofluid volume fraction (ϕ) are depicted. Results indicated that temperature gradient increases considerably with enhance of Ra and ϕ but it reduces with increases of Ha.

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Numerical Solution of Melting Processes for Fixed and Unfixed Phase Change Material in the Presence of Magnetic Field: Simulation of Low Gravity Environment

10.1115/imece2001/htd-24290 ◽

2001 ◽

Author(s):

Y. Asako ◽

E. Gonçalves ◽

M. Faghri ◽

M. Charmchi

Keyword(s):

Magnetic Field ◽

Natural Convection ◽

Phase Change ◽

Phase Change Material ◽

Flow Patterns ◽

Transport Processes ◽

Low Gravity ◽

Horizontal Magnetic Field ◽

Wall Heating ◽

Change Material

Abstract Transport processes associated with melting of an electrically conducting Phase Change Material (PCM), placed inside a rectangular enclosure, under low-gravity environment, and in the presence of a magnetic field is simulated numerically. Electromagnetic forces damp the natural convection as well as the flow induced by sedimentation and/or floatation, and thereby simulating the low gravity environment of outer space. Computational experiments are conducted for both side-wall heating and top-wall heating under horizontal magnetic field. The governing equations are discretized using a control-volume-based finite difference scheme. Numerical solutions are obtained for true low-gravity environment as well as for the simulated-low-gravity conditions resulted by the presence of a horizontal magnetic field. The effects of magnetic field on the natural convection, solid phase floatation/sedimentation, liquid-solid interface location, solid melting rate, and flow patterns are investigated. It is found that the melting under low-gravity environment can reasonably be simulated on earth via applying a strong horizontal magnetic field. However, the flow patterns obtained for the true low-gravity cases are not similar to the corresponding cases solved for the simulated-low-gravity environment.

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Instabilities of natural convection heat transfer from a horizontal cylinder to potassium under a horizontal magnetic field

Fusion Engineering and Design ◽

10.1016/s0920-3796(89)80117-6 ◽

1989 ◽

Vol 8 ◽

pp. 271-275 ◽

Cited By ~ 1

Author(s):

N. Takenaka ◽

O. Takahashi ◽

I. Michiyoshi

Keyword(s):

Magnetic Field ◽

Heat Transfer ◽

Natural Convection ◽

Convection Heat Transfer ◽

Horizontal Cylinder ◽

Natural Convection Heat Transfer ◽

Convection Heat ◽

Horizontal Magnetic Field

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Numerical Calculation of Three-Dimensional Turbulent Natural Convection in a Cubical Enclosure Using a Two-Equation Model for Turbulence

Journal of Heat Transfer ◽

10.1115/1.3247016 ◽

1986 ◽

Vol 108 (4) ◽

pp. 806-813 ◽

Cited By ~ 18

Author(s):

H. Ozoe ◽

A. Mouri ◽

M. Hiramitsu ◽

S. W. Churchill ◽

N. Lior

Keyword(s):

Natural Convection ◽

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Vertical Wall ◽

Three Dimensional ◽

Spiral Flow ◽

Vertical Side ◽

Turbulent Natural Convection ◽

Cubical Enclosure ◽

Side Walls

This paper presents a model and numerical results for turbulent natural convection in a cubical enclosure heated from below, cooled on a portion of one vertical side wall and insulated on all other surfaces. Three-dimensional balances were derived for material, energy, and the three components of momentum, as well as for the turbulent kinetic energy k and the rate of dissipation of turbulent kinetic energy ε. The constants used in the model were the same as those used by Fraikin et al. for two-dimensional convection in a channel. Illustrative transient calculations were carried out for Ra = 106 and 107 and Pr = 0.7. Both the dominant component of the vector potential and the Nusselt number were found to converge to a steady state. Isothermal lines and velocity vectors for vertical cross sections normal to the cooled wall indicated three-dimensional effects near the side walls. A top view of the velocity vectors revealed a downward spiral flow near the side walls along the cooled vertical wall. A weak spiral flow was also found along the side walls near the wall opposing the partially cooled one. The highest values of the eddy diffusivity were 2.6 and 5.8 times the molecular kinematic viscosity for Ra = 106 and 107, respectively. A coaxial double spiral movement, similar to that previously reported for laminar natural convection, was found for the time-averaged flow field. This computing scheme is expected to be applicable to other thermal boundary conditions.

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An Experimental Study of Magnetic Damping Effect on Temperature Gradient Induced Natural Convection in Liquid Gallium

Fluids Engineering ◽

10.1115/imece2004-59841 ◽

2004 ◽

Author(s):

B. Xu ◽

B. Q. Li ◽

D. E. Stock

Keyword(s):

Magnetic Field ◽

Natural Convection ◽

Liquid Gallium ◽

Horizontal Magnetic Field ◽

Magnetic Damping ◽

Damping Effect ◽

Different Temperatures ◽

Hot Film ◽

The Magnetic Field ◽

Good Agreement

The results of an experimental investigation of natural convection driven flow of liquid gallium are presented. The gallium contained by a rectangular box with two opposite ends held at different temperatures and is subject to a uniform horizontal magnetic field. The objective of this study was to examine the damping effect of a magnetic field on the natural convection in a liquid metal. A hot film anemometry was used to measure the velocity profile and a thermocouple was used to measure the temperature field. The hot-film probe was calibrated over a narrow range of temperatures in a rotating container fill with liquid gallium. The velocity and temperature profiles are compared with previous numerical simulations and reasonably good agreement was found. The damping effect of the external magnetic field was observed in both the temperature and the velocity profiles and found to increase as the strength of the magnetic field increases.

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