Boundary Layer and Heat Transfer Analysis in Liquid Film of Nanofluid Over an Unsteady Stretching Sheet

In this paper, thermal behavior of a liquid film of nanofluid over an unsteady stretching surface was studied. The governing partial differential equations of flow and heat transfer were transformed to the ordinary differential equations using appropriate similarity transformations. The resulting nonlinear ordinary differential equations were solved using forth order Runge-Kutta method. Comparisons were made between the obtained results and previously published results to show accuracy of solution. The effects of nanofluid concentration on the Nusselt number and skin friction were investigated carefully for various types of nanofluid which are named Cu-water, Al2O3-water and TiO2-water. It was found that increasing nanofluid concentration increases the reduced Nusselt number and the reduced skin friction. In addition, a comparison of employment of various types of nanofluids showed that using Cu-water causes the highest heat transfer rate and the lowest skin friction coefficient in comparison with the other used nanofluids.