Three-dimensional boundary layer flow of nanofluids due to an unsteady stretching surface

A numerical solution has been obtained for the unsteady three-dimensional stretching flow and heat transfer due to uncertainties of thermal conductivity and dynamic viscosity of nanofluids. The term of nanofluid refers to a solid–liquid mixture with a continuous phase which is a nanometer sized nanoparticle dispersed in conventional base fluids. The unsteadiness in the flow and temperature fields is caused by the time-dependent of the stretching velocity and the surface temperature. Different water-based nanofluids containing Cu, Ag, and TiO2 are taken into consideration. The governing partial differential equations with the auxiliary conditions are converted to ordinary differential equations with the appropriate corresponding conditions via scaling transformations. Comparison with known results for steady state flow is presented and it found to be in excellent agreement.