Flow and heat transfer of nanofluids at a stagnation point flow over a stretching/shrinking surface in a porous medium with thermal radiation

• Momentum boundary layer thickness decreases with an increase in ϕ  , when a/c>1a/c>1.
• Cu–water velocity is higher than Al2O3Al2O3–water and TiO2TiO2–water for stretching and shrinking sheets.
• Skin-friction coefficient increases with increasing the value of volume fraction ϕ.
• Decrease in suction parameter s>0s>0 decreases velocity profiles for Cu–water.
• Temperature for Cu–water increase with decreasing the suction parameter s>0s>0.

In this paper, the effects of thermal radiation and viscous dissipation on a stagnation point flow and heat transfer over a flat stretching/shrinking surface in nanofluids are analyzed. The effects of suction/injection are also considered. Using a similarity transformation, the governing equations are transformed into a system of nonlinear ordinary differential equations. The resulting system is then solved numerically by Runge–Kutta–Fehlberg method with shooting technique. It is observed that the local Nusselt number increases with increment in the suction/injection parameter for stretching sheet whereas reverse effect is observed for shrinking sheet. It is found that skin-friction coefficient increases for both stretching/shrinking sheet with increase in volume fraction of the nanoparticles.