Study of heat transfer characteristics of copper-water nanofluid in a differentially heated square cavity with different viscosity models

Effect of nanofluid (suspension of copper nanoparticles in water) has been studied as a cooling medium to simulate the behavior of heat transfer due to laminar natural convection in a differentially heated square cavity. The transport equations are solved numerically using the finite volume approach with the SIMPLER algorithm. The thermal conductivity of the nanofluid has been calculated from the model proposed by Patel et al. [2003, 2005]. The viscosity of the nanofluid has been calculated from the Brinkman [1952] model and also from experimental observations of Kwak and Kim [2005]. Study has been conducted for the Rayleigh number (Ra) from 10(4) to 10(7) while solid volume fraction (phi) of copper particles in water varied from 0% to 2%. For the first viscosity model, heat transfer increases with but it decreases for the second model. Also heat transfer increases with Ra. Correlations has been developed to obtain the average Nusselt number as a function of Ra and phi for both models. The copper nanoparticle diameter is 100 nm for all of our studies, which is constant.