Exact solutions for the flow of Casson fluid over a stretching surface with transpiration and heat transfer effects

The effects of transpiration on forced convection boundary layer non-Newtonian fluid flow and heat transfer toward a linearly stretching surface are reported. The flow is caused solely by the stretching of the sheet in its own plane with a velocity varying linearly with the distance from a fixed point. The constitutive relationship for the Casson fluid is used. The governing partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations by using similarity transformations. Exact solutions of the resulting ordinary differential equations are obtained. The effect of increasing Casson parameter, i.e., with decreasing yield stress (the fluid behaves as a Newtonian fluid as the Casson parameter becomes large), is to suppress the velocity field. However, the temperature is enhanced as the Casson parameter increases. It is observed that the effect of transpiration is to decrease the fluid velocity as well as the temperature. The skin-friction coefficient is found to increase as the transpiration parameter increases.