Boundary layer flow of a nanofluid past a stretching sheet with a convective boundary condition

The boundary layer flow induced in a nanofluid due to a linearly stretching sheet is studied numerically. The transport equations include the effects of Brownian motion and thermophoresis. Unlike the commonly employed thermal conditions of constant temperature or constant heat flux, the present study uses a convective heating boundary condition. The solutions for the temperature and nanoparticle concentration distributions depend on five parameters, Prandtl number Pr, Lewis number Le, the Brownian motion parameter Nb, the thermophoresis parameter Nt, and convection Riot number Bi. Numerical results are presented both in tabular and graphical forms illustrating the effects of these parameters on thermal and concentration boundary layers. The thermal boundary layer thickens with a rise in the local temperature as the Brownian motion, thermophoresis, and convective heating each intensify. The effect of Lewis number on the temperature distribution is minimal. With the other parameters fixed, the local concentration of nanoparticles increases as the convection Riot number increases but decreases as the Lewis number increases. For fixed Pr, Le, and Bi, the reduced Nusselt number decreases but the reduced Sherwood number increases as the Brownian motion and thermophoresis effects become stronger. (C) 2011 Elsevier Masson SAS. All rights reserved.