Mixed convection–radiation on stagnation-point flow of nanofluids over a stretching/shrinking sheet in a porous medium with heat generation and viscous dissipation

This paper is concerned with the effects of thermal radiation of mixed convection boundary layer flow towards a stagnation-point flow over a stretching/shrinking embedded in porous medium in nanofluids with heat generation and viscous dissipation. Dual solutions are obtained for shrinking sheet case. The basic equations are solved numerically by using Runge–Kutta–Fehlberg method with shooting technique. This method is more suitable to the present boundary value problem as it has advantages like automatic grid generation and convergence test in order to get very accurate results compared to Runge–Kutta-fourth order method which lacks these features. Results are compared with the previously published results and excellent agreement has been obtained. It is found that suction parameter decreases the velocity and temperature profiles for stretching sheet, whereas reverse trend is obtained for shrinking sheet. It is also found that the boundary layer thickness for second solution is higher than first solution for the three types of nanofluids for shrinking sheet. It is important to note that addition of nanoparticles into the base fluid produced an increase in the skin-friction.