Effects of suction/injection on flow and heat transfer over a permeable surface in presence of different nanofluids

In this study, flow and heat transfer of some nano-fluids over a permeable surface with convective boundary condition has been investigated. Four types of nano-fluids, i.e. Cu-water, Al2O3-water, TiO2-water and Ag-water are considered for investigation. The governing partial differential equations (PDEs) first transformed to ordinary differential equations (ODEs) using similarity solution method. The obtained equations then, solved numerically by making use of Runge–Kutta–Fehlberg fourth–fifth order’s (RKF45) method. The effects of nanoparticles type, volume fraction of nanoparticles, the type of permeability and convective boundary condition in three cases, i.e. suction, injection and impermeable surface, on the velocity and temperature variations as well as the local Nusselt number and skin friction coefficient are examined. The results show that some of above parameters have different effects in suction and injection states. The effect of nanoparticle volume fraction on velocity and temperature variations and then the local skin-friction coefficient and local Nusselt number are noticeably larger than in injection rather than suction or impermeable surfaces. In all cases, the increase of volume fraction lead to enhancement of local skin friction as well as Nusselt number. In the cases of suction and impermeable surfaces, the maximum friction coefficient was found with Ag-water as nano-fluid while the maximum Nusselt number observed with Cu-water nanofluid in suction.