Heat Transfer in Magnetohydrodynamic Flow in an Entrance Section

1965 ◽  
Vol 87 (2) ◽  
pp. 231-236 ◽  
Author(s):  
A. M. Dhanak
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Prandtl Number ◽  
Flat Plate ◽  
Hartmann Number ◽  
Transverse Magnetic ◽  
Entrance Section ◽  
Pressure Distributions ◽  
Prandtl Numbers ◽  
Iterative Procedures

Based on the Ka´rma´n-Pohlhausen method and the associated iterative procedures developed herein the analysis shows that the presence of a transverse magnetic field in the entrance section of a channel has significant effects on the velocity and pressure distributions, and on the displacement and momentum thicknesses. The calculations further reveal that the heat transfer from the channel, in contrast with the flat plate case, increases with the Hartmann number. This increase is, however, significant only at high Prandtl numbers. The influence of Joulean dissipation appears to be negligible for a Joulean parameter up to 1.0 and at a Prandtl number of unity.

Analytical Model of a Side-Heated Free Convection Loop Placed in a Transverse Magnetic Field

1998 ◽  
Vol 120 (1) ◽  
pp. 62-69 ◽  
Author(s):  
Nesreen Ghaddar
Keyword(s):  
Magnetic Field ◽  
Prandtl Number ◽  
Transverse Magnetic Field ◽  
Hartmann Number ◽  
Transverse Magnetic ◽  
Hydrodynamic Characteristics ◽  
Loop Model ◽  
Grashof Number ◽  
Prandtl Numbers ◽  
Buoyancy Driven Convection

The hydrodynamic characteristics of a buoyancy-driven convection loop containing an electrically-conducting fluid in a transverse magnetic field are investigated analytically using a one-dimensional model. One side of the loop is isothermally heated and the other side isothermally cooled, and the upper and lower sections are insulated. The model which is based on the use of the Hartmann Plane-Poiseuille flow solution for estimating loop shear stress, predicts the flow velocity and the induced current of the magnetohydrodynamic generator in terms of the flow and geometric parameters. The study covers ranges of Grashof number, Gr, from 102 to 106, the Hartmann number, Ha, from 0 to 20, the Prandtl number, Pr, from .003 to 7, and loop height to thickness ratio, L/d, from 10 to 50. It is shown that at low Prandtl numbers, Pr ≪ 1, there exists an optimal Hartmann number, Haopt, that maximizes the induced electric current. This Haopt depends weakly on the Grashof number. The side-heated loop performance is also compared with the bottom heated loop model of Ghaddar, (1997a). It is found that at a low Prandtl number, side heated loop induces the higher velocity whereas at high Prandtl numbers the bottom heated loop induces higher velocity.

scholarly journals Effect of magnetic field on the steady nanofluid flow past obstacle

2021 ◽  
Vol 22 (3) ◽  
pp. 535-542
Author(s):  
Yacine Khelili ◽  
Rafik Bouakkaz
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Laminar Flow ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Transverse Magnetic ◽  
Heated Wall ◽  
Cylinder Wake ◽  
Flow And Heat Transfer ◽  
Model Transition

The fluid flow and heat transfer of a nanofluid past a circular cylinder in a rectangular duct under a strong transverse magnetic field is studied numerically using a quasitwo-dimensional model. Transition from laminar flow with separation to creeping laminar flow is determined as a function of Hartmann number and the volume fraction of nanoparticle, as are critical Hartmann number, and the heat transfer from the heated wall to the fluid. Downstream cross-stream mixing induced by the cylinder wake was found to increase heat transfer. The successive changes in the flow pattern are studied as a function of the Hartmann number. Suppression of vortex shedding occurs as the Hartmann number increases.

scholarly journals Conjugate Effects of Buoyancy and Magnetic Field on Heat and Fluid Flow Pattern at Low-to-Moderate Prandtl Numbers

2016 ◽  
Vol 66 ◽  
pp. 79-95
Author(s):  
Ridha Djebali ◽  
Mohamed Ammar Abbassi ◽  
Ahlem Rouahi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Rayleigh Number ◽  
Prandtl Number ◽  
Threshold Value ◽  
Electrically Conducting ◽  
Viscous Forces ◽  
Side Walls ◽  
Prandtl Numbers ◽  
Energy Equations

This study aims to present a numerical investigation of unsteady two-dimensional natural convection of an electrically conducting fluid in a square medium under externally imposed magnetic field. A temperature gradient is applied between the two opposing side walls parallel to y-direction, while the floor and ceiling parallel to x-direction are kept adiabatic. The coupled momentum and energy equations associated with the Lorentz ‘decelerating’ force as well as the buoyancy force terms are solved using the single relaxation lattice Boltzmann (LB) approach. The flow is characterized by the Rayleigh number Ra (103-106), the Prandtl number Pr (0.01-10), the Hartman number Ha (0-100) determined by the strength of the imposed magnetic field and its tilt angle from x-axis ranging from 0° to 90°. The changes in the buoyant flow patterns and temperature contours due to the effects of varying the controlling parameters and associated heat transfer are examined. It was found that the developed thermal LB model gives excellent results by comparison with former experimental and numerical findings. Starting from the values 105 of the Rayleigh number Ra and Ha=0, the flow is unsteady multicellular for low Prandtl number typical of liquid metal. Increasing gradually Pr, the flow undergoes transition to steady bicellular. The transition occurs at a threshold value between Pr=0.01 and 0.1. Increasing more the Prandtl number, the flow structure is distorted due to the viscous forces which outweigh the buoyancy forces and a thermal stratification is clearly established. For high Hartman number, the damping effects suppress the unsteady behaviour and results in steady state with extended unicellular pattern in the direction of Lorentz force and the heat transfer rate is reduced considerably.

Simulation of Fully-Developed Average Turbulent MHD Pipe Flow With Heat Transfer

2012 ◽  
Author(s):  
K. Alammar ◽  
R. Vilagines ◽  
M. Shariff ◽  
Z. Kaneesamkandi ◽  
S. Abdullah
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Prandtl Number ◽  
Turbulence Model ◽  
Pipe Flow ◽  
Hartmann Number ◽  
Heat Transfer Characteristics ◽  
Enhance Heat Transfer ◽  
Prandtl Numbers ◽  
Grid Independence

Using a zero-equation turbulence model, fully-developed average turbulent MHD pipe flow with wall heating was simulated. Uncertainty was approximated through grid-independence and model validation. Effect of Reynolds, Hartmann, and Prandtl numbers on heat transfer characteristics was investigated. With increasing Hartmann number, heat transfer was shown to increase towards the side layer. Increasing the Prandtl number was shown to enhance heat transfer. Increasing the Reynolds number decreased the effect of the Hartmann number.

Natural Convection Heat Transfer in a Rectangular Enclosure With a Transverse Magnetic Field

1995 ◽  
Vol 117 (3) ◽  
pp. 668-673 ◽  
Author(s):  
S. Alchaar ◽  
P. Vasseur ◽  
E. Bilgen
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transverse Magnetic Field ◽  
Hartmann Number ◽  
Convection Heat Transfer ◽  
Transverse Magnetic ◽  
Temperature Profiles ◽  
Flow Approximation ◽  
Buoyancy Driven Convection ◽  
The Magnetic Field

In this paper the effect of a transverse magnetic field on buoyancy-driven convection in a shallow rectangular cavity is numerically investigated (horizontal Bridgman configuration). The enclosure is insulated on the top and bottom walls while it is heated from one side and cooled from the other. Both cases of a cavity with all rigid boundaries and a cavity with a free upper surface are considered. The study covers the range of the Rayleigh number, Ra, from 102 to 105, the Hartmann number, Ha, from 0 to 102, the Prandtl number, Pr, from 0.005 to 1 and aspect ratio of the cavity, A, from 1 to 6. Comparison is made with an existing analytical solution (Garandet et al., 1992), based on a parallel flow approximation, and its range of validity is delineated. Results are presented for the velocity and temperature profiles and heat transfer in terms of Ha number. At high Hartmann numbers, both analytical and numerical analyses reveal that the velocity gradient in the core is constant outside the two Hartmann layers at the vicinity of the walls normal to the magnetic field.

Heat Transfer in Liquid Metal at an Upward Flow in a Pipe in Transverse Magnetic Field

2020 ◽  
Vol 58 (3) ◽  
pp. 400-409
Author(s):  
N. A. Luchinkin ◽  
N. G. Razuvanov ◽  
I. A. Belyaev ◽  
V. G. Sviridov
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Liquid Metal ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Upward Flow
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