Effects of uncertainties of conductivity models on mixed convection for Al2O3-water nano uid

The present numerical study aims to investigate the eects of uncertainties of dierent conductivity models on mixed convection uid 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 uid eective 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 dierences between the average Nusselt numbers predicted by the ve employed conductivity models.