E ffects of uncertainties of conductivity models on mixed convection for Al2O3-water nano fluid

The present numerical study aims to investigate the e ects of uncertainties of di erent conductivity models on mixed convection fluid ow and heat transfer in a square cavity lled with Al2O3-water nano uid. 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 nano fluid e ective thermal conductivity, ve most commonly used models, namely, Maxwell, Khanafer and Vafai, Corcione, Chon et al., and Patel et al., 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 signi cant di erences between the average Nusselt numbers predicted by the ve employed conductivity models.