Entropy generation under the influence of radial magnetic field and viscous dissipation of generalized Couette flow in an annulus

In this study, the influences of the applied magnetic field and fluid elasticity were investigated for a nonlinear viscoelastic fluid obeying the Carreau equation between concentric annulus where the inner cylinder rotates at a constant angular velocity and the outer cylinder is stationary. The governing motion and energy balance equations are coupled while viscous dissipation is taken into account, adding complexity to the already highly correlated set of differential equations. The numerical solution is obtained for the narrow gap limit and steady-state base flow. Magnetic field effect on local entropy generation due to steady two-dimensional laminar forced convection flow was investigated. This study was focused on the entropy generation characteristics and its dependency on various dimensionless parameters. The effects of the Hartmann number, the Brinkman number, the Deborah number, and the fluid elasticity on the stability of the flow were investigated. The application of the magnetic field induces a resistive force acting in the opposite direction of the flow, thus causing its deceleration. Moreover, the study shows that the presence of magnetic field tends to slowdown the fluid motion and thus increases the fluid temperature. However, the total entropy generation number decreases as the Hartmann number and fluid elasticity increase and it increases with increasing Brinkman number.

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The effect of a radial magnetic field on the stability of Couette flow

Canadian Journal of Physics ◽

10.1139/p94-038 ◽

1994 ◽

Vol 72 (5-6) ◽

pp. 258-265 ◽

Cited By ~ 1

Author(s):

M. A. Ali

Keyword(s):

Magnetic Field ◽

Eigenvalue Problem ◽

Incompressible Fluid ◽

Couette Flow ◽

Wave Number ◽

Rotating Cylinders ◽

Radial Magnetic Field ◽

Electrically Conducting ◽

Angular Velocities ◽

The Stability

The effect of a radial magnetic field on the stability of an electrically conducting incompressible fluid between two concentric rotating cylinders is considered. The eigenvalue problem for determining the critical Taylor number TC and the corresponding wave number aC is solved numerically for different values of ±μ(= Ω2/Ω1), (where Ω1, and Ω2 are me angular velocities of the inner and outer cylinders, respectively) and for different gap sizes. It is observed that the radial magnetic field stabilizes the flow. This effect is more pronounced for cylinders that are corotating as compared with counter-rotating cylinders or the situation where only the inner one is rotating.

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Effects of magnetic field and viscous dissipation on entropy generation of mixed convection in porous lid-driven cavity with corner heater

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-11-2014-0344 ◽

2016 ◽

Vol 26 (5) ◽

pp. 1548-1566 ◽

Cited By ~ 11

Author(s):

Sameh E Ahmed ◽

Hakan F. Öztop ◽

Khaled Al-Salem

Keyword(s):

Magnetic Field ◽

Heat Transfer ◽

Mixed Convection ◽

Viscous Dissipation ◽

Entropy Generation ◽

Hartmann Number ◽

Heat Transfer Fluid ◽

Content Type ◽

Driven Cavity ◽

Corner Heater

Purpose – The purpose of this paper is to investigate the effects of magnetic field and viscous dissipation on mixed convection heat transfer, fluid flow and entropy generation in a porous media filled square enclosure heated with corner isothermal heater. Design/methodology/approach – Finite volume method has been used to solve governing equations. A code is developed by FORTRAN and entropy generation is calculated from the obtained results of velocities and temperature. Results are presented via streamlines, isotherms, local and mean Nusselt number for different values of Richardson number (0.001=Ri=100), Hartmann number (0.001=Ha=100), Darcy number (0.001=Da=0.1), length of heaters (0.25=hx=hy=0.75) and viscous dissipation factors (10−4=ε=10−6). Findings – It is observed that entropy is generated mostly due to lid-driven wall and right side of the heater. Entropy generation decreases with increasing of Hartmann number and heat transfer increases with decreasing of viscous parameter. Originality/value – The originality of this work is to application of magnetic field and viscous dissipation on entropy generation in a lid-driven cavity with corner heater. Here, both corner heater and the external forces are original parameters.

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Entropy Generation Optimization in Squeezing Magnetohydrodynamics Flow of Casson Nanofluid with Viscous Dissipation and Joule Heating Effect

Entropy ◽

10.3390/e21080747 ◽

2019 ◽

Vol 21 (8) ◽

pp. 747 ◽

Cited By ~ 8

Author(s):

Muhammad Zubair ◽

Zahir Shah ◽

Abdullah Dawar ◽

Saeed Islam ◽

Poom Kumam ◽

...

Keyword(s):

Magnetic Field ◽

Skin Friction ◽

Viscous Dissipation ◽

Entropy Generation ◽

Joule Heating ◽

Volume Fraction ◽

Bejan Number ◽

Parallel Plates ◽

Casson Nanofluid ◽

Porosity Parameter

In this research article, the investigation of the three-dimensional Casson nanofluid flow in two rotating parallel plates has been presented. The nanofluid has been considered in steady state. The rotating plates have been considered porous. The heat equation is considered to study the magnetic field, joule heating, and viscous dissipation impacts. The nonlinear ordinary system of equations has been solved analytically and numerically. For skin friction and Nusslt number, numerical results are tabulated. It is found that velocity declines for higher values of magnetic and porosity parameter while it is heightened through squeezing parameter. Temperature is an enhancing function for Eckert number and nanoparticles volume fraction. Entropy generation is augmented with radiation parameter, Prandtl, and Eckert numbers. The Casson, porosity, magnetic field, and rotation parameters were reduced while the squeezing and suction parameters increased the velocity profile along x-direction. The porosity parameter increased the Bejan number while the Eckert and Prandtl numbers decreased the Bejan number. Skin friction was enhanced with increasing the Casson, porosity, and magnetic parameters while it decreased with enhancing rotation and squeezing parameters. All these impacts have been shown via graphs. The influences by fluid flow parameters over skin friction and Nusselt number are accessible through tables.

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Numerical study on combined thermal radiation and magnetic field effects on entropy generation in unsteady fluid flow past an inclined cylinder

Journal of Computational Design and Engineering ◽

10.1093/jcde/qwaa068 ◽

2020 ◽

Author(s):

Zachariah Mbugua Mburu ◽

Sabyasachi Mondal ◽

Precious Sibanda

Keyword(s):

Magnetic Field ◽

Fluid Flow ◽

Thermal Radiation ◽

Viscous Dissipation ◽

Chemical Reaction ◽

Entropy Generation ◽

Magnetic Field Effects ◽

Slip Conditions ◽

Field Effects ◽

Flow Past

Abstract This study reports on combined thermal radiation, chemical reaction, and magnetic field effects on entropy generation in an unsteady nanofluid flow past an inclined cylinder using the Buongiorno model. We consider the impact of viscous dissipation, velocity slip conditions, thermal slip conditions, and the Brownian motion. The transport equations governing the flow are solved using an overlapping grid spectral collocation method. The results indicate that entropy generation is suppressed significantly by thermal radiation and chemical reaction parameters but enhanced with the magnetic field, viscous dissipation, the Brinkman number, and the Reynolds number. Also, fluid flow variables are affected by the thermophoresis parameter, the angle of cylinder inclination, and the Richardson number. We present the findings of the skin friction coefficient, the Nusselt number, and the Sherwood number. The model is applicable in fields such as the petroleum industry, building industries, and medicine.

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Interactions of Porosity-Magnetic Field and Viscous Dissipation in an Inclined Channel Type Flow

2010 14th International Heat Transfer Conference, Volume 2 ◽

10.1115/ihtc14-23323 ◽

2010 ◽

Author(s):

Murat Havzali ◽

Guven Komurgoz ◽

Aytac Arikoglu ◽

Haci Ibrahim Keser ◽

Ibrahim Ozkol

Keyword(s):

Magnetic Field ◽

Viscous Dissipation ◽

Entropy Generation ◽

Thermal Characteristics ◽

Darcy Number ◽

Transverse Magnetic ◽

Constant Heat Flux ◽

Bejan Number ◽

Entropy Generation Number ◽

Inclined Channel

In this work, entropy generation due to laminar viscous incompressible flow of a conducting fluid in the presence of a transverse magnetic field in a porous inclined channel is investigated. Fully developed flow field is solved analytically whereas the solution of the energy equation is obtained by Finite Difference Method (FDM). The boundary conditions at the walls are considered to be constant heat flux. The influence of the applied magnetic field, porous medium and the viscous dissipation on velocity, temperature and entropy generation is examined. The dependence of flow and thermal characteristics on Peclet number (Pe), Brinkman number (Br), Darcy number (Da) and Hartman number (Ha) is analyzed through velocity and temperature distribution as well as Entropy generation number (Ns) and Bejan Number (Be) profiles.

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MHD Couette Flow in Cylindrical Porous Annulus with Perfectly Conducting Walls

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.284-287.829 ◽

2013 ◽

Vol 284-287 ◽

pp. 829-833

Author(s):

Sian Wun Guo ◽

Jik Chang Leong

Keyword(s):

Magnetic Field ◽

Porous Medium ◽

Analytical Solution ◽

Couette Flow ◽

Outer Cylinder ◽

Variable Order ◽

Radial Magnetic Field ◽

Mhd Couette Flow ◽

The Magnetic Field ◽

Direction Opposite

This work obtained an analytical solution for a steady cylindrical MHD Couette flow in a porous medium between two perfectly conducting rotating cylinders under the influence of a non-uniform radial magnetic field. Since part of the analytical solution is expressed in terms of the integral of the Modified Bessel function of the first and second kinds of variable order, numerical integration was performed. Current results indicate that the flow may become more uniform when the strength of the external magnetic field is increased. The magnetic fluid tends to slow down if the permeability of the porous medium decreases. If the porous annulus is thick, the momentum of the flow is more difficult to propagate from the outer cylinder into the inner part of the annulus. If both the inner and outer cylinders rotate, the shear effect the inner cylinder imposes is only relatively influential in the region close to it. A decrease in Da no less than 10-2 may increase the amount of magnetic field induced. The transfer of momentum across the annular space is easier in a thin porous annulus than a thick one and hence induces a stronger magnetic field. If the inner cylinder rotates in the direction opposite of the outer one, the magnetic field in the clockwise direction will be induced in some region.

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