Free-convective flow of copper/water nanofluid about a rotating down-pointing cone using Tiwari-Das nanofluid scheme

Here, Tiwari-Das nanofluid scheme has been used to investigate the laminar free-convective flow and heat transfer of an electrically conducting nanofluid in the presence of a transverse magnetic field over a rotating down-pointing vertical cone. Three different types of water-based nanofluid with copper, aluminum oxide (alumina) and titanium dioxide (titania) as nanoparticles are considered while the investigation's emphasis is on copper/water nanofluid. Using the local similarity method, it is shown that a set of suitable similarity transformations reduces the non-linear coupled partial differential equations (PDEs) governing on the problem into a set of non-linear coupled ordinary differential equations (ODEs), which is solved analytically by the well-known homotopy analysis method (HAM) and numerically using the Keller-box method (KBM). The velocity profile, temperature distribution, skin friction coefficient and local Nusselt number are determined for various values of the physical parameters. The computations illustrate that selecting alumina and copper as the nanoparticle leads to the minimum and maximum amounts of skin friction coefficient value, and also copper and titania nanoparticles have the largest and lowest local Nusselt number. Moreover, it can be observed that the spin of the body augments the velocity profiles and compresses the temperature profiles toward the surface where as cause an increasing effect on both the skin friction coefficient and local Nusselt number. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V.