Simulation of Natural Convection Heat Transfer in Complex Cavity Filled with Nano-Fluids

Abstract

This paper reports a numerical simulation of natural convection mode of heat flow in a complex enclosure having Aspect ratio (A=1). This complex enclosure consists of  heated hot wall (313K) and cold wall (293K) on either side, together with all other impermeable walls filled with Al₂O₃-EG-Water nanofluid mixture having different temperature dependent properties. These problems are stated as vorticity stream function formulation and the resulting governing equation are solved numerically using the finite differential method. Boussinesq approximation model is used for fluid property including density variation. Simple quick scheme is used for general boundary conditions, for validation a comparison with previously published work is done and the results found to be in good agreement. The volume fraction of nanoparticle mixture is φ= 0%, 10% and 20% considered for three cases which are compared later in this study. Various results for streamline and isotherm contours are presented for a wide range of Rayleigh Number (10³ - 10⁶). Local and Average Nusselt number are also calculated. The complex geometry seems to have a significant effect on the behaviour of the Average Nusselt number which increases as volume fraction of the nanofluids and Rayleigh number increases. Also, the fluid flow inside the enclosure is in Brownian motion and as the ratio of nanoparticle and Rayleigh number increases causes convection mode of heat transfer regime to substantially enhance.