Influence of size, shape, type of nanoparticles, type and temperature of the base fluid on natural convection MHD of nanofluids

In this paper, we have presented MHD natural convection boundary layer flow, heat and mass transfer characteristics of nanofluid through porous media over a vertical cone influenced by different aspects of nanoparticles such as size, shape, type of nanoparticles and type of the base fluid and working temperature of base fluid. To increase the physical significance of the problem, we have taken dynamic viscosity and thermal conductivity as the functions of local volume fraction of nanoparticles. The drift-flux model of nanofluids, Brownian motion, thermophoresis, and enhancement ratio parameters are also considered in the present analysis. The influence of non-dimensional parameters such as magnetic field (M), buoyancy ratio parameter (Nr), conductivity parameter (Nc), viscosity parameter (Nv), Brownian motion parameter (Nb), thermophoresis parameter (Nt), Lewis number (Le) on velocity, temperature and volume fraction of nanoparticles in the boundary layer region is examined in detail. Furthermore the impact of these parameters on local Nusselt number (Nu(x)) and enhancement ratio (h(nf)/h(bf)) is also investigated. The results of present study reveal that significant natural convection heat transfer enhancement is noticed as the size of nanoparticles decreases. Moreover, type of the nanoparticles and type of the base fluid also influenced the natural convection heat transfer. (C) 2016 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).