Browsing by Author "Tshehla, M. S."

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    Analysis of heat transfer in Berman flow of nanofluids with Navier slip, viscous dissipation, and convective cooling
    (Hindawi Publishing Corporation, 2014-03-31) Makinde, O. D.; Khamis, S.; Tshehla, M. S.; Franks, O.
    Heat transfer characteristics of a Berman flow of water based nanofluids containing copper (Cu) and alumina (Al2O3) as nanoparticles in a porous channel with Navier slip, viscous dissipation, and convective cooling are investigated. It is assumed that the exchange of heat with the ambient surrounding takes place at the channel walls following Newton’s law of cooling. The governing partial differential equations and boundary conditions are converted into a set of nonlinear ordinary differential equations using appropriate similarity transformations. These equations are solved analytically by regular perturbation methods with series improvement technique and numerically using an efficient Runge-Kutta Fehlberg integration technique coupled with shooting scheme.The effects of the governing parameters on the dimensionless velocity, temperature, skin friction, pressure drop, and Nusselt numbers are presented graphically and discussed quantitatively.
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    Analysis of thermal stability in a convecting and radiating two-step reactive slab
    (Hindawi, 2013) Makinde, O. D.; Tshehla, M. S.
    This paper investigates the combined effects of convective and radiative heat loss on thermal stability of a rectangular slab of combustible materials with internal heat generation due to a two-step exothermic chemical reaction, taking the diffusion of the reactant into account and assuming a variable (temperature dependent) preexponential factor. The nonlinear differential equation governing the transient reaction-diffusion problem is obtained and tackled numerically using a semidiscretization finite difference technique. A special type of Hermite-Pade approximants coupled with perturbation technique are employed to analyze the effects of ´ various embedded thermophysical parameters on the steady state problem. Important properties of the temperature field including thermal stability conditions are presented graphically and discussed quantitatively.
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    The flow of a variable viscosity fluid down an inclined plane with a free surface
    (Hindawi, 2013) Tshehla, M. S.
    The effect of a temperature dependent variable viscosity fluid flow down an inclined plane with a free surface is investigated.The fluid film is thin, so that lubrication approximation may be applied. Convective heating effects are included, and the fluid viscosity decreases exponentially with temperature. In general, the flow equations resulting from the variable viscosity model must be solved numerically. However, when the viscosity variation is small, then an asymptotic approximation is possible. The full solutions for the temperature and velocity profiles are derived using the Runge-Kutta numerical method.The flow controlling parameters such as the nondimensional viscosity variation parameter, the Biot and the Brinkman numbers, are found to have a profound effect on the resulting flow profiles.
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    Unsteady hydromagnetic flow of radiating fluid past a convectively heated vertical plate with the Navier slip
    (Hindawi Publishing Corporation, 2014-04-17) Makinde, O. D.; Tshehla, M. S.
    This paper investigates the unsteady hydromagnetic-free convection of an incompressible electrical conducting Boussinesq’s radiating fluid past a moving vertical plate in an optically thin environment with the Navier slip, viscous dissipation, and Ohmic and Newtonian heating. The nonlinear partial differential equations governing the transient problem are obtained and tackled numerically using a semidiscretization finite difference method coupled with Runge-Kutta Fehlberg integration technique. Numerical data for the local skin friction coefficient and the Nusselt number have been tabulated for various values of parametric conditions. Graphical results for the fluid velocity, temperature, skin friction, and the Nusselt number are presented and discussed. The results indicate that the skin friction coefficient decreases while the heat transfer rate at the plate surface increases as the slip parameter and Newtonian heating increase.