An Unsteady Double-Diffusive Natural Convection in an Inclined Rectangular Enclosure with Different Angles of Magnetic Field

2016 ◽  
Vol 13 (04) ◽  
pp. 1641015 ◽  
Author(s):  
Sabyasachi Mondal ◽  
Precious Sibanda
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Staggered Grid ◽  
Convection Flow ◽  
Rectangular Enclosure ◽  
Nusselt Numbers ◽  
Inclination Angles ◽  
The Magnetic Field ◽  
Buoyancy Ratio ◽  
Double Diffusive

An unsteady double-diffusive natural convection flow in an inclined rectangular enclosure subject to an applied magnetic field and heat generation parameter is studied. The enclosure is heated and concentrated from one side and cooled from the adjacent side. The other two sides are adiabatic. The governing equations are solved numerically using a staggered grid finite-difference method to determine the streamline, isotherm and iso-concentration contours. We have further obtained the average Nusselt numbers and average Sherwood numbers for various values of buoyancy ratio and different angles of the magnetic field by considering three different inclination angles of the enclosure while keeping the aspect ratio fixed. The results indicate that the flow pattern, temperature and concentration fields are significantly dependent on the buoyancy ratio and the magnetic field angles. It is found that different angles of the magnetic field suppress the convection flow and its direction influences the flow patterns. This leads to the appearance of inner loop and multiple eddies.

The effect of an external magnetic field on natural convection in an inclined rectangular enclosure

2007 ◽  
Vol 221 (12) ◽  
pp. 1609-1622 ◽  
Author(s):  
M C Ece ◽  
E Büyük
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Differential Quadrature Method ◽  
Convection Flow ◽  
Rectangular Enclosure ◽  
Aspect Ratios ◽  
Inclination Angles ◽  
Side Walls ◽  
Vertical Walls ◽  
The Magnetic Field

Steady, laminar, natural-convection flow in the presence of a magnetic field of an arbitrary direction in an inclined rectangular enclosure with isothermal vertical walls and adiabatic horizontal walls was considered. The governing equations were solved numerically for the stream function, vorticity, and temperature ratio using the differential quadrature method for various Grashof and Hartman numbers and three different magnetic field directions, aspect ratios, and inclination angles. Counter-clockwise inclination of the enclosure enhances the convection whereas the clockwise inclination retards it. The magnetic field applied normal to the side walls are more effective for square and tall enclosures whereas the magnetic field applied parallel to the side walls is more effective for shallow enclosures.

Effect of a Magnetic Field on the Heat Transfer Rate on Free Convection in a Rectangular Cavity

2005 ◽  
Author(s):  
Gustavo Gutierrez ◽  
Ezequiel Medici
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stokes Equations ◽  
Rectangular Cavity ◽  
Convection Flow ◽  
Interesting Phenomenon ◽  
The Magnetic Field

The interaction between magnetic fields and convection is an interesting phenomenon because of its many important engineering applications. Due to natural convection motion the electric conductive fluid in a magnetic field experiences a Lorenz force and its effect is usually to reduce the flow velocities. A magnetic field can be used to control the flow field and increase or reduce the heat transfer rate. In this paper, the effect of a magnetic field in a natural convection flow of an electrically conducting fluid in a rectangular cavity is studied numerically. The two side walls of the cavity are maintained at two different constant temperatures while the upper wall and the lower wall are completely insulated. The coupling of the Navier-Stokes equations with the Maxwell equations is discussed with the assumptions and main simplifications assumed in typical problems of magnetohydrodynamics. The nonlinear Lorenz force generates a rich variety of flow patterns depending on the values of the Grashof and Hartmann numbers. Numerical simulations are carried out for different Grashof and Hartmann numbers. The effect of the magnetic field on the Nusselt number is discussed as well as how convection can be suppressed for certain values of the Hartmann number under appropriate direction of the magnetic field.

scholarly journals Non-Darcian effect on double-diffusive natural convection inside aninclined square Dupuit-Darcy porous cavity under a magnetic field

2019 ◽  
pp. 271-271
Author(s):  
Redha Rebhi ◽  
Noureddine Hadidi ◽  
Rachid Bennacer
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Numerical Study ◽  
Lewis Number ◽  
Boussinesq Approximation ◽  
Buoyant Force ◽  
Porous Cavity ◽  
Effect Parameter ◽  
The Magnetic Field ◽  
Double Diffusive

This paper presents a numerical study of a double diffusive convection in an inclined square porous cavity filled with an electrically conducting binary mixture. The upper and bottom walls are maintained at a constant temperatures and concentrations whereas the left and right walls are assumed to be adiabatic and impermeable. A uniform and tilted magnetic field is applied at an angle, ?, about the horizontal, it is obvious that this is related to the orientation of the magnetic force that can help or oppose the buoyant force. The Dupuit-Darcy flow model, which includes effects of the inertial parameter, with the Boussinesq approximation, energy and species transport equations are solved numerically using the classical finite difference method. Governing parameters of the problem under study are the thermal Rayleigh number, Rt, Hartmann number, Ha, Lewis number, Le, the buoyancy ratio, ?,inclination angle, ? and tilting angle of the magnetic field, ?,. The numerical results are reported on the contours of streamline, temperature, and concentration and for the average Nusselt and Sherwood numbers for various parametric conditions. It is demonstrated that both the inertial effect parameter and the magnetic field, have a strong influence on the strength of the natural convection heat and mass transfer within the porous layer.

scholarly journals A Tilted Lorentz Force Effect on Porous Media Filled with Nanofluid

2018 ◽  
Vol 48 (2) ◽  
pp. 50-71
Author(s):  
M. Muthtamilselvan ◽  
S. Sureshkumar
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Staggered Grid ◽  
Convection Flow ◽  
The Magnetic Field

Abstract This paper is intended to investigate the effects of an inclined magnetic field on the mixed convection flow in a lid-driven porous enclosure filled with nanofluid. Both the left and right vertical walls of the cavity are thermally insulated while the bottom and top horizontal walls are maintained at constant but different temperatures. The governing equations are solved numerically by using finite volume method on a uniformly staggered grid system. The computational results are obtained for various combinations of Richardson number, Darcy number, Hartmann number, inclination angle of magnetic field, and solid volume fraction. It is found that the presence of magnetic field deteriorates the fluid flow, which leads to a significant reduction in the overall heat transfer rate. The inclination angle of magnetic field plays a major role in controlling the magnetic field strength and the overall heat transfer rate is enhanced with the increase of inclination angle of magnetic field. Adding the nanoparticles in the base fluid significantly increases the overall heat transfer rate in the porous medium whether the magnetic field is considered or not.

Investigating Double Diffusive Convection in an Inclined Rectangular Porous Enclosure Subjected to Magnetic Field

2009 ◽  
Author(s):  
Behnam Moghadassian ◽  
Pooyan Razi ◽  
Hossein Shokouhmand
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Flow Characteristics ◽  
Darcy Number ◽  
Double Diffusive Convection ◽  
Diffusive Convection ◽  
Dimensional Parameters ◽  
The Magnetic Field ◽  
Buoyancy Ratio ◽  
Double Diffusive

The problem of double diffusive convection in an inclined rectangular enclosure filled with a uniform porous medium at the presence of magnetic field has been studied. The constant temperature and concentration are imposed along two opposing walls, while the other two walls are adiabatic and impermeable to mass transfer. Non-dimensional governing equations are solved using the finite difference method. The representative results illustrates streamline, temperature, concentration and density contours as well as non-dimensional parameters of heat and mass transfer versus changes in magnitude and direction of magnetic field, buoyancy ratio, Darcy number and inclination angle of the enclosure. One of the main results is that average Nusselt and Sherwood numbers and flow characteristics depend significantly on the buoyancy ratio, Darcy number and direction of the magnetic field. Also it is observed that there is a decreasing trend in the average Nusselt and Sherwood numbers with increasing strength of the magnetic field.

Magnetohydrodynamic Natural Convection in a Rotating Enclosure

2016 ◽  
Vol 8 (2) ◽  
pp. 279-292
Author(s):  
H. Saleh ◽  
I. Hashim
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Vertical Direction ◽  
Staggered Grid ◽  
Governing Equations ◽  
Coriolis Forces ◽  
Velocity Pressure ◽  
The Magnetic Field

AbstractMagnetohydrodynamic natural convection heat transfer in a rotating, differentially heated enclosure is studied numerically in this article. The governing equations are in velocity, pressure and temperature formulation and solved using the staggered grid arrangement together with MAC method. The governing parameters considered are the Hartmann number, 0≤Ha≤70, the inclination angle of the magnetic field, 0°≤θ 90°, the Taylor number, 8.9 x 104≤Ta≤1.1 x 106 and the centrifugal force is smaller than the Coriolis force and the both forces were kept below the buoyancy force. It is found that a sufficiently large Lorentz force neutralizes the effect of buoyancy, inertial and Coriolis forces. Horizontal or vertical direction of the magnetic field was most effective in reducing the global heat transfer.

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