Lattice Boltzmann simulation of natural convection heat transfer in nanofluids

In this study, lattice Boltzmann method is applied to investigate the natural convection flows utilizing nanofluids in a square cavity. The fluid in the cavity is a water-based nanofluid containing Al2O3 or Cu nanoparticles. The study has been carried out for the Rayleigh number 10(3)-10(6) and the solid volume fraction 0-0.05. The effective thermal conductivity and viscosity of nanofluid are calculated by Chon and Brinkman models, respectively. The effects of solid volume fraction of nanofluids on hydrodynamic and thermal characteristics are investigated and discussed. The average and local Nusselt numbers, streamlines, temperature contours and vertical component of velocity for different values of solid volume fraction and Rayleigh number are illustrated. The results indicate that by increasing solid volume fraction, the average Nusselt number increases for both nanofluids. It is found that the effects of solid volume fraction for Cu are stronger than Al2O3. (C) 2011 Elsevier Masson SAS. All rights reserved.