Free Convection Flow and Heat Transfer of Nanofluids of Different Shapes of Nano-size particles ...

In this paper, free convection flow and heat transfer of nanofluids of different shapes nano-size particles over a vertical plate at very low and high Prandtl number are analyzed. The governing systems of nonlinear partial differential equations of the flow and heat transfer processes are converted to systems of nonlinear ordinary differential equation through similarity transformations. The resulting systems of fully coupled nonlinear ordinary differential equations are solved using differential transformation method-Padé approximant technique. The accuracies of the developed analytical methods are verified by comparing their results with the results of past works as presented in literature. Thereafter, the analytical solutions are used to investigate the effects of Prandtl number, nanoparticles volume-fraction, shape and type on the flow and heat transfer behaviour of various nanofluids over the flat plate. It is observed that the velocity and temperature of the nanofluid decreases and increases, respectively as the Prandtl number and volume-fraction of the nanoparticles in the basefluid increase. Also, the maximum decrease in velocity and maximum increase in temperature are caused lamina shaped nanoparticle and followed by platelets, cylinder, bricks and sphere shaped nanoparticles, respectively. Using a common basefluid to all the nanoparticle type, it was established that the maximum decrease in velocity and maximum increase in temperature are caused by TiO2 and followed by CuO, Al2O3 and SWCNTs nanoparticles, in that order. It is hoped that the present study will enhance the understanding of free convection boundary-layer problems as applied in various engineering processes.