Numerical Investigation of Natural Convective Heat Transfer of Nanofluids in a Rectangular Cavity

This paper presents an explicit finite-volume model which has been developed to study two dimensional incompressible natural convection in a square enclosure filled with Al2O3 Water nanofluid that operates under differentially heated walls. As boundary conditions of cavity, two opposite left and right walls were kept at constant but different temperatures. Also two opposite bottom and top walls were thermally insulated. The Navier-Stokes and energy equations are solved, numerically. Heat transfer and fluid flow are examined for parameters of non-uniform nanoparticle size, mean nanoparticle diameter, nanoparticle volume fraction, Grashof number, Prandtl number and different geometries of enclosure. At this work, for solving of the governing equations an explicit finite-volume procedure and a time-marching method are utilized, and the forth order rungkuta is used for discretizating time expressions. Also instead of the conventional algorithms of SIMPLE, SIMPLEM and SIMPLEC, an artificial compressibility technique is applied for coupling the continuity to the momentum equations. Results indicate that using nanofluid causes an increase in the heat transfer and the Nusselt number. Furthermore; by decreasing the mean diameters of nanoparticles, Nusselt number increases. By increasing R nano particle volume fraction, Nusselt number increases.