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1

Post-stagnation-point boundary layer flow and mixed convection heat transfer over a vertical, linearly stretching sheet

Ishak A., Nazar R., Pop I.

Archives of Mechanics

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2008

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Vol. 60, nr 4

303-322

EN

A theoretical analysis is made for the steady two-dimensional post-stagnationpoint flow of an incompressible viscous fluid over a stretching vertical sheet in its own plane. The stretching velocity, the free stream velocity and the surface temperature are assumed to vary linearly with the distance from the stagnation point. The governing partial differential equations are transformed into a coupled system of ordinary differential equations, which is then solved numerically by a finite-difference method. Results are presented in terms of the skin friction coefficient and local Nusselt number, along with a selection of velocity and temperature profiles. It was shown that for both cases of a fixed surface (? = 0) and a stretching surface (? = 0), dual solutions exist for the assisting flow (positive values of the buoyancy parameter ?), besides that usually reported in the literature for the opposing flow (? < 0). It was also found that for the assisting flow, a solution exists for all values of ? (> 0), while for the opposing flow, a solution exists only if the magnitude of the buoyancy parameter is small.

2

Steady and unsteady boundary layers due to a stretching vertical sheet in a porous medium using Darcy-Brinkman equation model

Ishak A., Nazar R., Pop I.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 3

623-637

EN

The present paper deals with the analysis of steady and unsteady boundary layer flow and heat transfer past a vertical stretching sheet in a viscous fluid-saturated porous medium by using the Darcy-Brinkman equation model. It is assumed that unsteadiness is caused by the impulsive stretching of the sheet and by sudden increase in the surface temperature. The problem is reduced to parabolic partial differential equations, which are solved numerically using the Keller-box method. The small time (initial unsteady flow) as well as the large time (final steady-state flow) solutions are also included in the analysis. It is shown that there is a smooth transition from the small time solution to large time solution, respectively.

3

Flow of a micropolar fluid on a continuous moving surface

Ishak A., Nazar R., Pop I.

Archives of Mechanics

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2006

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Vol. 58, nr 6

529-541

EN

The present paper deals with the analysis of steady boundary layer flow and heat transfer of a micropolar fluid on an isothermal continuously moving plane surface. It is assumed that the microinertia density is variable and not constant, as in many other published papers. Also, the viscous dissipation effect is taken into account. The basic partial differential equations are reduced to a system of nonlinear ordinary differential equations, which is solved numerically using the Keller-box method. Numerical results are obtained for the skin friction coefficient, local Nusselt number, as well as velocity, temperature and microrotation profiles. Results are shown in graphical form and the numerical values for the skin friction coefficient and local Nusselt number are given in the form of tables. The effects of material parameter K, Prandtl number Pr and Eckert number Ec on the flow and heat transfer characteristics are discussed.