Effects of conductivity models uncertainties on mixed convection for Al2O3 –water nanofluid

Abstract

Present numerical study aims to investigate the uncertainties effects of different conductivity models on mixed convection fluid flow and heat transfer in a square cavity filled with Al2O3-water nanofluid. The left and right vertical sides of enclosure are maintained at high and low constant temperatures, respectively, while the bottom and top horizontal sides of the enclosure are kept insulated. Furthermore, the right wall moves from down to up with a constant velocity Vp. To approximate the nanofluid effective thermal conductivity, five most commonly used models, namely, Maxwell, Khanafer and Vafai, Corcione, Chon et al., and Patel et al. models, are employed. Finite volume method and SIMPLER algorithm are used in order to discretize the governing equations. Simulations are performed for nanoparticles volume fraction ranging from 0 to 0.05 and Richardson number ranging between 0.01 and 100. The results indicate that there are significant differences between the average Nusselt numbers predicted by five employed conductivity models.