Lattice Boltzmann simulation of double diffusive natural convection of nanofluids in an enclosure with heat conducting partitions and sinusoidal boundary conditions

Abstract In present work numerical simulation of double diffusive natural convection of nanofluids in an enclosure with heat conducting partitions vertically attached to the horizontal walls has been considered. Sinusoidal boundary conditions are applied to the right side wall of the enclosure filled with Cu-water nanofluid. The Maxwell-Garnett model is used in the governing equation to modify the fluid properties affected by Cu nanoparticles. Solution of governing equation was performed via the lattice Boltzmann method (LBM). The effect of thermal Rayleigh number (10 3 ≤ Ra ≤ 10 5 ), nanoparticle volume fraction (0 ≤ φ ≤ 0.08), phase deviation (0 ≤ ξ ≤ π), thermal conductivity ratio (10 −2 ≤ Kr ≤ 10 2 ) was investigated. The results indicate that the position of partitions is a major factor in controlling the heat and mass transfer rates of nanofluids, and made the average Nusselt and Sherwood numbers are linearly related to the change of nanoparticle volume fraction. In addition, there is an optimal phase deviation value at which the maximum heat and mass transfer enhancement is obtained. Moreover, increasing in the thermal conductivity ratio results to the heat and mass transfer enhancement by properly setting the position of the partitions.