Showing papers by "Oluwole Daniel Makinde published in 2008"

The effect of thermal radiation on the heat and mass transfer flow of a variable viscosity fluid past a vertical porous plate permeated by a transverse magnetic field

Abstract: The effect of temperature-dependent viscosity on free convective flow past a vertical porous plate is studied in the presence of a magnetic field, thermal radiation, and a first-order homogeneous chemical reaction. Boundary layer equations are derived and the resulting approximate nonlinear ordinary differential equations are solved numerically by the shooting method. A parametric study of all parameters involved is conducted, and a representative set of numerical results for the velocity and temperature profiles as well as the skin-friction parameter and the Nusselt and Sherwood numbers is illustrated graphically to show typical trends of the solutions. The dynamic viscosity in this study is taken as a function of the temperature although the Prandtl number is considered constant.

Magnetohydrodynamic Mixed-Convective Flow and Heat and Mass Transfer Past a Vertical Plate in a Porous Medium With Constant Wall Suction

Abstract: The problem of steady laminar hydromagnetic heat transfer by mixed convection flow over a vertical plate embedded in a uniform porous medium in the presence of a uniform normal magnetic field is studied. Convective heat transfer through porous media has wide applications in engineering problems such as in high temperature heat exchangers and in insulation problems. We construct solutions for the free convection boundary-layer flow equations using an Adomian–Pade approximation method that in the recent past has proven to be an able alternative to the traditional numerical techniques. The effects of the various flow parameters such as the Eckert, Hartmann, and Schmidt numbers on the skin friction coefficient and the concentration, velocity, and temperature profiles are discussed and presented graphically. A comparison of our results with those obtained using traditional numerical methods in earlier studies is made, and the results show an excellent agreement. The results demonstrate the reliability and the efficiency of the Adomian–Pade method in an unbounded domain.

Unsteady hydromagnetic free convection flow of a dissipative and radiating fluid past a vertical plate with constant heat flux

Abstract: The effect of thermal radiation absorption on an unsteady free convective flow past a vertical plate is studied in the presence of a magnetic field and constant wall heat flux. Boundary layer equations are derived, and the resulting approximate nonlinear ordinary differential equations are solved analytically using asymptotic technique. A parametric study of all parameters involved is conducted, and a representative set of numerical results for the velocity and temperature profiles as well as the skin-friction parameter are illustrated graphically to show typical trends of the solutions.

Effect of arbitrary magnetic Reynolds number on MHD flows in convergent‐divergent channels

Abstract: – The objective of the present study is to investigate the effect of arbitrary magnetic Reynolds number on steady flow of an incompressible conducting viscous liquid in convergent‐divergent channels under the influence of an externally applied homogeneous magnetic field., – The solution of the non‐linear 2D Navier‐Stokes equations modeling the flow field is obtained using a perturbation technique coupled with a special type of Hermite‐Pade approximation method implemented numerically on MAPLE and a bifurcation study is performed., – The results show that increasing values of magnetic Reynolds number causes a general decrease in the fluid velocity around the central region of the channel. The flow reversal control is also observed by increasing magnetic field intensity. The bifurcation study reveals the solution branches and turning points., – The reported results are very useful in the field of engineering flow control and industrial metal casting for the control of molten metal flows., – Effect of arbitrary magnetic Reynolds on the overall flow structure in converging‐diverging channels are presented and studied using a newly developed numerical approach.

Thermal criticality and entropy analysis for a variable viscosity Couette flow

Abstract: This study investigates the thermal criticality and inherent irreversibility in a variable viscosity Couette flow. The two plates are kept at two constant but different temperatures, while the viscosity of the fluid is assumed to be temperature dependent. The coupled set of the equations of motion and the energy including the viscous terms becomes nonlinear and is solved analytically using a perturbation method coupled with a special type of Hermite–Pade approximation technique to obtain the velocity and temperature distributions together with thermal criticality conditions which essentially expedite to obtain expressions for volumetric entropy generation numbers, irreversibility distribution ratio and the Bejan number in the flow field.

On Nonperturbative Techniques for Thermal Radiation Effect on Natural Convection past a Vertical Plate Embedded in a Saturated Porous Medium

Abstract: In this article, the heat transfer characteristics of natural convection about a vertical permeable flat surface embedded in a saturated porous medium are studied by taking into account the thermal radiation effect. The plate is assumed to have a power-law temperature distribution. Similarity variables are employed in order to transform the governing partial differential equations into a nonlinear ordinary differential equation. Both Adomian decomposition method (ADM) and He's variational iteration method (VIM) coupled with Pade approximation technique are implemented to solve the reduced system. Comparisons with previously published works are performed, and excellent agreement between the results is obtained.

Irreversibility analysis of variable viscosity channel flow with convective cooling at the walls

Abstract: This study investigates the inherent irreversibility in the flow of a variable (temperature-dependent) viscosity fluid through a channel with parallel plates. The channel is narrow so that the lubrication approximation may be applied, and the temperature-dependent nature of viscosity is assumed to follow an exponential model. The system is assumed to exchange heat with the ambient surroundings following Newton’s cooling law. Using a perturbation method coupled with a special type of Hermite–Pade approximation technique, the simplified governing nonlinear equations are solved and the important properties of overall flow structure, including velocity field, temperature field, and thermal criticality conditions are derived, which essentially expedite obtaining expressions for volumetric entropy generation numbers, irreversibility distribution ratio, and the Bejan number in the flow field. PACS Nos.: 44.10.+a, 47.11.–j, 47.15.gm

Application of Lie point symmetry and Adomain decomposition techniques to thermal-storage nonlinear diffusion models

Abstract: Classical Lie point symmetry techniques are employed to time dependent nonlinear heat diffusion equations describing thermal energy storage in a medium subjected to a convective heat transfer to the surrounding environment at the boundary through a variable heat transfer coefficient. Exponential temperature-dependent thermal conductivity and heat capacity are assumed. Group classification for the source term is performed and some exciting large symmetry algebras are admitted. It turns out that the principal Lie algebra extends when the source term vanishes and when it is given as the exponential function of temperature. Reduction by one of the independent variables is performed for some realistic choices of the source term. In some case the resulting nonlinear ordinary differential equation with appropriate corresponding conditions are solved using Adomian decomposition method.

Modelling Transmission Dynamics of Childhood Diseases in the Presence of a Preventive Vaccine: Application of Adomian Decomposition Technique

Abstract: In recent time, diligent vaccination campaigns have resulted in high levels of permanent immunity against the childhood disease among the population, e.g.measles, mumps, rubella, poliomyelitis, etc. In this paper, a SIR model that monitors the temporal dynamics of a childhood disease in the presence of a preventive vaccine is developed. The qualitative analysis reveals the vaccination reproductive number for disease control and eradication. Adomian decomposition method is also employed to compute an approximation to the solution of the non-linear system of differential equations governing the problem. Graphical results are presented and discussed quantitatively to illustrate the solution.

Modelling the Thermal Operation in a Catalytic Converter of an Automobile's Exhaust

Abstract: Catalytic converter in an automobile’s exhaust system is made up of a finely divided platinum–iridium catalyst (i.e. forming a porous matrix) and provides a platform for exothermic chemical reaction where unburned hydrocarbons completely combust. In this paper, the steady-state solutions of a strongly exothermic reaction of a viscous combustible fluid (fuel) in a catalytic converter-modelled as a cylindrical pipe filled with a saturated porous medium under Arrhenius kinetics, neglecting reactant consumption, are presented. The Brinkman flow model is employed. Having known the velocity distribution, the nonlinear energy equation is solved using a perturbation technique together with a special type of Hermite– Padé approximants and the important properties of the temperature field including bifurcations and thermal criticality are discussed.