The boundary layers of an unsteady stagnation-point flow in a nanofluid

The boundary layer of an unsteady two-dimensional stagnation-point flow of a nanofluid is further investigated. The similarity equations are solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al2O3), and titania (TiO2) in the water based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, the local Nusselt number, and the velocity and temperature profiles are presented and discussed. Effects of the solid volume fraction parameter phi on the fluid flow and heat transfer characteristics are thoroughly examined. Interesting observation is that there are dual solutions seen for negative values of the unsteadiness parameter A (decelerating flow with A < 0). (C) 2012 Elsevier Ltd. All rights reserved.