Lattice Boltzmann simulation of natural convection heat transfer of Al2O3/water nanofluids in a square enclosure

In the present study, mathematical modeling is performed to simulate natural convection of Al2O3/water nanofluids in a vertical square enclosure using the lattice Boltzmann method (LBM). Results indicate that the average Nusselt number increases with the increase of Rayleigh number and particle volume concentration. The average Nusselt number with the use of nanofluid is higher than the use of water under the same Rayleigh number. However, the heat transfer rate of the nanofluid takes on a lower value than water at a fixed temperature difference across the enclosure mainly due to the significant enhancement of dynamic viscosity. Furthermore, great deviations of computed Nusselt numbers using different models associated with the physical properties of a nanofluid are revealed. The present results are well validated with the works available in the literature and consequently LBM is robust and promising for practical applications. (C) 2011 Elsevier Masson SAS. All rights reserved.