Double Population MRT LBM in an Enclosure Using Nanofluid

Abstract

In this study, lattice Boltzmann method is applied to investigate the natural convection flows utilizing nanofluids in a square enclosure. Al₂O₃ and CuO water based nanofluids with 5, 6, 7, 8 and 9% nanoparticle volume fraction are used as the fluid. This study has been carried out for the pertinent parameters in the following ranges: the Rayleigh number of nanofluid, Ra=103, 104, 105 and 106, the volumetric fraction of nanoparticles 5, 6, 7, 8 and 9% and the aspect ratio (Ar) of the enclosure is 1.0. 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. Results show that by increasing Rayleigh number and nanoparticle volume fraction, average Nusselt number increases in whole range of Rayleigh numbers that lead to decreasing thermal boundary layer and enhancement of heat transfer of fluid in the cavity. As expected, Al₂O₃ with higher heat conductivity has higher Nusselt number with respect to CuO with lower heat conductivity.