scholarly journals The effect of an external magnetic field on the entropy generation in three-dimensional natural convection

2010 ◽  
Vol 14 (2) ◽  
pp. 341-352 ◽  
Author(s):  
Lioua Kolsi ◽  
Awatef Abidi ◽  
Naceur Borjini ◽  
Ben Aïssia
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
External Magnetic Field ◽  
Liquid Metal ◽  
Entropy Generation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Laminar Natural Convection ◽  
The Magnetic Field

A 3-D original numerical study of entropy generation in the case of liquid metal laminar natural convection in a differentially heated cubic cavity and in the presence of an external magnetic field orthogonal to the isothermal walls is carried out. The effect of this field on the various types of irreversibilities is analyzed. It was observed that in the presence of a magnetic field the generated entropy is distributed on the entire cavity and that the magnetic field limits the 3-D character of the distribution of the generated entropy.

scholarly journals Magnetohydrodynamics, Natural Convection, and Entropy Generation of CuO–Water Nanofluid in an I-Shape Enclosure—A Numerical Study

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Ali Malekpour ◽  
Nader Karimi ◽  
Amirfarhang Mehdizadeh
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Entropy Generation ◽  
Numerical Study ◽  
Heat Transfer Process ◽  
Geometrical Parameters ◽  
Strong Function ◽  
Exact Shape ◽  
The Magnetic Field

Abstract This paper presents a numerical study of the magnetohydrodynamics, natural convection, and thermodynamic irreversibilities in an I-shape enclosure, filled with CuO-water nanofluid and subject to a uniform magnetic field. The lateral walls of the enclosure are maintained at different but constant temperatures, while the top and bottom surfaces are adiabatic. The Brownian motion of the nanoparticles is taken into account and an extensive parametric study is conducted. This involves the variation of Rayleigh and Hartmann numbers, and the concentration of nanoparticles and also the geometrical specifications of the enclosure. Further, the behaviors of streamlines and isotherms under varying parameters are visualized. Unlike that in other configurations, the rate of heat transfer in the I-shaped enclosure appears to be highly location dependent and convection from particular surfaces dominates the heat transfer process. It is shown that interactions between the magnetic field and natural convection currents in the investigated enclosure can lead to some peculiarities in the thermal behavior of the system. The results also demonstrate that different parts of the enclosure may feature significantly different levels of heat transfer sensitivity to the applied magnetic field. Further, the analysis of entropy generation indicates that the irreversibility of the system is a strong function of the geometrical parameters and that the variations in these parameters can minimize the total generation of entropy. This study clearly shows that ignoring the exact shape of the enclosure may result in major errors in the prediction of heat transfer and second law performances of the system.

Natural convection with volumetric heat generation and external magnetic field in differentially heated enclosure

2014 ◽  
Vol 228 (15) ◽  
pp. 2711-2727 ◽  
Author(s):  
Farid Berrahil ◽  
Smail Benissaad ◽  
Abid Chérifa ◽  
Marc Médale
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
External Magnetic Field ◽  
Prandtl Number ◽  
Heat Generation ◽  
Numerical Study ◽  
Internal Heat ◽  
Internal Heat Generation ◽  
Simpler Algorithm ◽  
The Magnetic Field

Abstract This work presents a numerical study of natural convection in a laterally heated cavity filled with an electrically conductive fluid ([Formula: see text]) in the presence of an external magnetic field and an internal heat source. The finite volume method with the SIMPLER algorithm is used to solve the system of equations governing the magnetohydrodynamics flow. The influence of volumetric heating SQ on the flow structure and on the heat transfer within the cavity for Gr = 104, 105, and 106 was examined. The effects of aspect ratio ( A = 1, 0.5, and 2), Prandtl number (low Prandtl number fluids), and magnetic field ([Formula: see text] to [Formula: see text]) were determined in the steady state with internal heat generation. Two orientations of the magnetic field were considered in order to have better control of the flow. The strongest stabilization of the flow field with internal heat generation is found when the magnetic field is oriented horizontally.

scholarly journals Numerical study of three-dimensional natural convection and entropy generation in a cubical cavity with partially active vertical walls

2017 ◽  
Vol 10 ◽  
pp. 100-110 ◽  
Author(s):  
Abdullah A.A.A Al-Rashed ◽  
Lioua Kolsi ◽  
Ahmed Kadhim Hussein ◽  
Walid Hassen ◽  
Mohamed Aichouni ◽  
...  
Keyword(s):  
Natural Convection ◽  
Entropy Generation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vertical Walls ◽  
Cubical Cavity

scholarly journals Numerical Study of Periodic Magnetic Field Effect on 3D Natural Convection of MWCNT-Water/Nanofluid with Consideration of Aggregation

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 957 ◽  
Author(s):  
Lioua Kolsi ◽  
Hakan Oztop ◽  
Kaouther Ghachem ◽  
Mohammed Almeshaal ◽  
Hussein Mohammed ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Three Dimensional ◽  
Magnetic Field Effect ◽  
Oscillation Period ◽  
Governing Equations ◽  
Periodic Magnetic Field ◽  
Aggregation Effect ◽  
Volume Method ◽  
The Magnetic Field

In this paper, a numerical study is performed to investigate the effect of a periodic magnetic field on three-dimensional free convection of MWCNT (Mutli-Walled Carbone Nanotubes)-water/nanofluid. Time-dependent governing equations are solved using the finite volume method under unsteady magnetic field oriented in the x-direction for various Hartmann numbers, oscillation periods, and nanoparticle volume fractions. The aggregation effect is considered in the evaluation of the MWCNT-water/nanofluid thermophysical properties. It is found that oscillation period, the magnitude of the magnetic field, and adding nanoparticles have an important effect on heat transfer, temperature field, and flow structure.

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