scholarly journals Unsteady/Steady Hydromagnetic Convective Flow between Two Vertical Walls in the Presence of Variable Thermal Conductivity

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. M. Hamza ◽  
I. G. Usman ◽  
A. Sule
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Skin Friction ◽  
Numerical Solutions ◽  
Nonlinear Partial Differential Equations ◽  
Vertical Channel ◽  
Approximate Solutions ◽  
Variable Thermal Conductivity ◽  
Convection Flow

Unsteady as well as steady natural convection flow in a vertical channel in the presence of uniform magnetic field applied normal to the flow region and temperature dependent variable thermal conductivity is studied. The nonlinear partial differential equations governing the flow have been solved numerically using unconditionally stable and convergent semi-implicit finite difference scheme. For steady case, approximate solutions have been derived for velocity, temperature, skin friction, and the rate of heat transfer using perturbation series method. Results of the computations for velocity, temperature, skin friction, and the rate of heat transfer are presented graphically and discussed quantitatively for various parameters embedded in the problem. An excellent agreement was found during the numerical computations between the steady-state approximate solutions and unsteady numerical solutions at steady-state time. In addition, comparison with previously published work is performed and the results agree well.

Instability of Variable Thermal Conductivity Magnetohydrodynamic Nanofluid Flow in a Vertical Porous Channel of Varying Width

2017 ◽  
Vol 378 ◽  
pp. 85-101
Author(s):  
Md. Sarwar Alam ◽  
Oluwole Daniel Makinde ◽  
Md. Abdul Hakim Khan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Differential Equations ◽  
Entropy Generation ◽  
Fluid Velocity ◽  
Nonlinear Partial Differential Equations ◽  
Vertical Channel ◽  
Porous Wall ◽  
Variable Thermal Conductivity ◽  
Physical Parameters

A numerical investigation is performed into the heat transfer and entropy generation of a variable thermal conductivity magnetohydrodynamic flow of Al2O3-water nanofluid in a vertical channel of varying width with right porous wall, which enable the fluid to enter. The effects of the Lorentz force, buoyancy force, viscous dissipation and Joule heating are considered and modeled using the transverse momentum and energy balance equations respectively. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations using appropriate similarity transformations and then solved numerically using power series with Hermite-Padé approximation method. A stability analysis has been performed for the local rate of shear stress and Nusselt number that indicates the existence of dual solution branches. Numerical results are achieved for the fluid velocity, temperature as well as the rate of heat transfer at the wall and the entropy generation of the system. The present results are original and new for the flow and heat transfer past a channel of varying width in a nanofluid which shows that the physical parameters have significant effects on the flow field.

Combined effect of variable viscosity and thermal conductivity on free convection flow of a viscous fluid in a vertical channel

2016 ◽  
Vol 26 (1) ◽  
pp. 18-39 ◽  
Author(s):  
Jawali C Umavathi ◽  
A J Chamkha ◽  
Syed Mohiuddin
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Variable Viscosity ◽  
Vertical Channel ◽  
Variable Thermal Conductivity ◽  
Convection Flow ◽  
Free Convection Flow ◽  
Temperature Relation ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose – The purpose of this paper is to investigate the effect of exponential viscosity-temperature relation, exponential thermal conductivity-temperature relation and the combined effects of variable viscosity and variable thermal conductivity on steady free convection flow of viscous incompressible fluid in a vertical channel. Design/methodology/approach – The governing equations are solved analytically using regular perturbation method. The analytical solutions are valid for small variations of buoyancy parameter and the solutions are found up to first order for variable viscosity. Since the analytical solutions have a restriction on the values of perturbation parameter and also on the higher order solutions, the authors resort to numerical method which is Runge-Kutta fourth order method. Findings – The skin friction coefficient and the Nusselt number at both the plates are derived, discussed and their numerical values for various values of physical parameters are presented in tables. It is found that an increase in the variable viscosity enhances the flow and heat transfer, whereas an increase in the variable thermal conductivity suppresses the flow and heat transfer for variable viscosity, variable thermal conductivity and their combined effect. Originality/value – This research is relatively original as, to the best of the authors’ knowledge, not much work is done on the considered problem with variable properties.

scholarly journals Unsteady Flow of Reactive Viscous, Heat Generating/Absorbing Fluid with Soret and Variable Thermal Conductivity

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
I. J. Uwanta ◽  
M. M. Hamza
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Skin Friction ◽  
Sherwood Number ◽  
Vertical Channel ◽  
Variable Thermal Conductivity ◽  
Finite Difference Schemes ◽  
Transfer Coefficients ◽  
Flow Parameters ◽  
Viscous Heat

This study investigates the unsteady natural convection and mass transfer flow of viscous reactive, heat generating/absorbing fluid in a vertical channel formed by two infinite parallel porous plates having temperature dependent thermal conductivity. The motion of the fluid is induced due to natural convection caused by the reactive property as well as the heat generating/absorbing nature of the fluid. The solutions for unsteady state temperature, concentration, and velocity fields are obtained using semi-implicit finite difference schemes. Perturbation techniques are used to get steady state expressions of velocity, concentration, temperature, skin friction, Nusselt number, and Sherwood number. The effects of various flow parameters such as suction/injection (γ), heat source/sinks (S), Soret number (Sr), variable thermal conductivityδ, Frank-Kamenetskii parameterλ, Prandtl number (Pr), and nondimensional timeton the dynamics are analyzed. The skin friction, heat transfer coefficients, and Sherwood number are graphically presented for a range of values of the said parameters.

Steady-State Conduction With Variable Thermal Conductivity

1962 ◽  
Vol 84 (1) ◽  
pp. 92-93 ◽  
Author(s):  
Robert K. McMordie
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Variable Thermal Conductivity ◽  
Two Dimensional ◽  
The Real ◽  
State Heat ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Transfer Problems

A method is developed for solving two-dimensional, steady-state heat-transfer problems with thermal conductivity dependent on temperature. The quantity ∫ KdT is employed in the analysis and although this quantity has been known for some time,2, 3 it seems that the real usefulness of this quantity in analysis has not been, in general, recognized.

Analysis of Nonlinear Heat Transfer in Solids of Various Geometries with Variable Thermal Conductivity and Heat Source

2017 ◽  
Vol 377 ◽  
pp. 1-16
Author(s):  
Raseelo Joel Moitsheki ◽  
Oluwole Daniel Makinde
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Exact Solutions ◽  
Heat Generation ◽  
Numerical Solutions ◽  
Internal Heat ◽  
Variable Thermal Conductivity ◽  
Internal Heat Generation ◽  
Temperature Dependent ◽  
Power Law Function

In this paper we consider heat transfer in a hot body with different geometries. Here, the thermal conductivity and internal heat generation are both temperature-dependent. This assumption rendered the model considered to be nonlinear. We assume that thermal conductivity is given by a power law function. We employ the preliminary group classification to determine the cases of internal heat generation for which the principal Lie algebra extends by one. Exact solutions are constructed for the case when thermal conductivity is a differential consequence of internal heat generation term. We derive the approximate numerical solutions for the cases where exact solutions are difficult to construct or are nonexistent. The effects of parameters appearing in the model on temperature profile are studied.

scholarly journals Joule heating and MHD free convection flow along a vertical wavy surface with viscosity and thermal conductivity dependent on temperature

2013 ◽  
Vol 10 (2) ◽  
pp. 81-98 ◽  
Author(s):  
Nazma Parveen ◽  
Md. Abdul Alim
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Friction Coefficient ◽  
Free Convection ◽  
Skin Friction ◽  
Joule Heating ◽  
Skin Friction Coefficient ◽  
Wavy Surface ◽  
Convection Flow ◽  
Free Convection Flow

A numerical study is conducted to analyze the effect of Joule heating and MHD (magnetohydrodynamic) free convection flow and heat transfer along a uniformly heated vertical wavy surface with temperature dependent variable viscosity and thermal conductivity. The governing boundary layer equations with associated boundary conditions for phenomenon are converted to non-dimensional form using the appropriate transformations. The resulting nonlinear system of partial differential equations are mapped into the domain of a vertical flat plate and solved numerically by employing implicit finite difference method, known as the Keller-box scheme. The behavior of the fluid in the ranges of Joule heating parameter (0.0–2.0), viscosity parameter (0.0–20.0) and thermal conductivity parameter (0.0 –10.0) are explained in details. It is found that the flow and temperature fields are strongly dependent on the above stated parameters for the ranges considered. The skin friction coefficient and the rate of heat transfer are also presented. The skin friction coefficient and the heat transfer for different values of Prandtl number Pr are compared with previously published work and are found to be in excellent agreement.DOI: http://dx.doi.org/10.3329/jname.v10i2.11707

scholarly journals Unsteady/Steady Natural Convection Flow of Reactive Viscous Fluid in a Vertical Annulus

2013 ◽  
Vol 18 (1) ◽  
pp. 73-83 ◽  
Author(s):  
B.K. Jha ◽  
A.K. Samaila ◽  
A.O. Ajibade
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Differential Equations ◽  
Viscous Fluid ◽  
Skin Friction ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Vertical Annulus ◽  
Analytical Expressions

This paper presents both analytical and numerical analyses of a fully developed unsteady/steady natural convection flow of a reactive viscous fluid in an open ended vertical annulus. Analytical expressions for velocity, temperature, skin-friction and rate of heat transfer are obtained after simplifying and solving the governing differential equations with reasonable approximations. The interesting result found in this study is that an increase in non-dimensional time (t) , increases both temperature and velocity profiles until a steady-state value is attained. Subsequent results obtained by numerical calculations show excellent agreement with analytical results.

scholarly journals Conjugate effects of temperature sensitive viscosity and thermal conductivity on free convection flow along a wavy surface with heat generation

2013 ◽  
Vol 10 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Md. Abdul Alim ◽  
M. Miraj Akand ◽  
M. Rezaul Karim
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Friction Coefficient ◽  
Skin Friction ◽  
Heat Generation ◽  
Skin Friction Coefficient ◽  
Numerical Results ◽  
Wavy Surface ◽  
Convection Flow ◽  
Surface Shear Stress

The effects of internal heat generation on natural convection flow with temperature dependent variable viscosity along a uniformly heated vertical wavy surface have been investigated. The governing boundary layer equations are first transformed into a non-dimensional form using suitable set of dimensionless variables. The resulting nonlinear system of partial differential equations are mapped into the domain of a vertical flat plate and then solved numerically employing the implicit finite difference method, known as Keller-box scheme. Numerical results of the surface shear stress in terms of skin friction coefficient and the rate of heat transfer in terms of local Nusselt number, the stream lines as well as the isotherms are shown graphically for a selection of parameters set consisting of viscosity variation parameter e, thermal conductivity parameter g, heat generation parameter Q and Prandtl number Pr. Numerical results of the local skin friction coefficient and the rate of heat transfer for different values are presented in tabular form and graphically.DOI: http://dx.doi.org/10.3329/jname.v10i2.9450

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