Variable heat flux effect on magnetohydrodynamic flow and heat transfer over an unsteady stretching sheet in the presence of thermal radiation

2014 ◽  
Vol 92 (1) ◽  
pp. 86-91 ◽  
Author(s):  
Ahmed M. Megahed
Keyword(s):  
Heat Flux ◽  
Thermal Radiation ◽  
Stretching Sheet ◽  
Magnetic Parameter ◽  
Skin Friction Coefficient ◽  
Magnetohydrodynamic Flow ◽  
Time Index ◽  
Unsteady Stretching Sheet ◽  
Variable Heat ◽  
Variable Heat Flux

The unsteady laminar magnetohydrodynamic flow over an unsteady stretching sheet in the presence of thermal radiation and variable heat flux is investigated. The governing time-dependent boundary layer equations are transformed into ordinary differential equations containing a radiation parameter, space index parameter, time index parameter, Prandtl number, magnetic parameter, and unsteadiness parameter. These equations are solved numerically by applying the Chebyshev spectral method. The velocity profiles, temperature profiles, the skin friction coefficient, and the dimensionless surface temperature are computed and discussed in detail for various values of the different parameters. It is found that increasing the unsteadiness parameter leads to a fall for both the velocity and temperature distribution. Moreover, the temperature increases with the magnetic parameter, but the reverse is true for the velocity distribution. Likewise, the temperature decreases for increasing both values of space index parameter and time index parameter.

scholarly journals Magnetohydrodynamic Fluid Flow due to an Unsteady Stretching Sheet with Thermal Radiation, Porous Medium, and Variable Heat Flux

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ahmed M. Megahed ◽  
Nourhan I. Ghoneim ◽  
M. Gnaneswara Reddy ◽  
Mostafa El-Khatib
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Thermal Radiation ◽  
Stretching Sheet ◽  
Variable Viscosity ◽  
Unsteady Stretching Sheet ◽  
Variable Heat ◽  
Variable Heat Flux ◽  
Conductivity Parameter ◽  
Efficient Heat Transfer

A shooting method has been introduced for determining the numerical solution of the ordinary differential equations which describe the Newtonian magnetohydrodynamic laminar fluid flow due to an unsteady stretching sheet together with the presence of thermal radiation and variable heat flux. The variable viscosity and variable conductivity are taken into consideration. Absence of magnetic field in some studies restricts the development of the energy-efficient heat transfer mechanism as is desired in numerous applications. The present study encompasses parameters such as unsteadiness parameter, porous parameter, viscosity parameter, magnetic number, radiation parameter, and conductivity parameter. It has been consummated that the proposed model is superior to other existing models for the industrial fluid.

scholarly journals Radiative Heat Transfer Flow of Micropolar Fluid with Variable Heat Flux in a Porous Medium

2008 ◽  
Vol 13 (1) ◽  
pp. 71-87 ◽  
Author(s):  
M. M. Rahman ◽  
T. Sultana
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Micropolar Fluid ◽  
Skin Friction Coefficient ◽  
Similarity Solutions ◽  
Local Similarity ◽  
Local Skin ◽  
Micropolar Fluids ◽  
Variable Heat ◽  
Variable Heat Flux

A two-dimensional steady convective flow of a micropolar fluid past a vertical porous flat plate in the presence of radiation with variable heat flux has been analyzed numerically. Using Darcy-Forchheimer model the corresponding momentum, microrotation and energy equations have been solved numerically. The local similarity solutions for the flow, microrotation and heat transfer characteristics are illustrated graphically for various material parameters. The effects of the pertinent parameters on the local skin friction coefficient, plate couple stress and the heat transfer are also calculated. It was shown that large Darcy parameter leads to decrease the velocity while it increases the angular velocity as well as temperature of the micropolar fluids. The rate of heat transfer in weakly concentrated micropolar fluids is higher than strongly concentrated micropolar fluids.

scholarly journals Modeling and simulation of natural convection flow along a rough surface of sinusoidal nature with variable heat flux: Using Keller box scheme

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3391-3400
Author(s):  
Abuzar Ghaffari ◽  
Tariq Javed ◽  
Irfan Mustafa ◽  
Fotini Labropulu
Keyword(s):  
Heat Flux ◽  
Nusselt Number ◽  
Natural Convection ◽  
Skin Friction Coefficient ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Local Skin ◽  
Variable Heat ◽  
Variable Heat Flux ◽  
Local Skin Friction

In this study, natural convection flow along a vertical wavy surface has been investigated with variable heat flux. The governing equations are transformed into dimensionless PDE by using the non-dimensional variables and then solved numerically by using an implicit finite difference scheme known as Keller Box method. The effects of the parameters amplitude of the wavy surface, ?, exponent of the variable heat flux, m, and Prandtl number on the local skin friction coefficient and local Nusselt number are shown graphically. It is found that for the negative value of exponent of the variable heat flux, m, the local skin friction coefficient increases and Nusselt number decreases but the opposite behavior is observed for the positive values of m. The comparison of limiting case with the previous study is shown through table and it is found that the solution obtained is in excellent agreement with the previous studies.

Natural convection on a vertical plate with variable heat flux in supercritical fluids

2013 ◽  
Vol 74 ◽  
pp. 115-127 ◽  
Author(s):  
Ali Reza Teymourtash ◽  
Danyal Rezaei Khonakdar ◽  
Mohammad Reza Raveshi
Keyword(s):  
Heat Flux ◽  
Natural Convection ◽  
Supercritical Fluids ◽  
Vertical Plate ◽  
Variable Heat ◽  
Variable Heat Flux

Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

2016 ◽  
Vol 30 (16) ◽  
pp. 1650155 ◽  
Author(s):  
Ebrahim Afshari ◽  
Masoud Ziaei-Rad ◽  
Nabi Jahantigh
Keyword(s):  
Heat Flux ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Pressure Drop ◽  
Flow Field ◽  
Pem Fuel Cells ◽  
Coolant Flow ◽  
Temperature Uniformity ◽  
Variable Heat ◽  
Variable Heat Flux

In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

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