Study of laminar natural convection in a vertical annulus with inner wall covered by a porous layer by using lattice Boltzmann method

Laminar natural convection in a vertical annulus with inner wall covered by a porous layer is numerically studied in this paper by using a multiple-relaxation-time lattice Boltzmann (MRT LB) model for the axisymmetric thermal flow in porous media at the representative element volume (REV) scale. The effects of the Rayleigh number, Darcy number, thermal diffusivity ratio and thickness of the porous layer on the overall heat transfer rate are investigated. It is found that wrapping with a porous layer can serve as a useful tool for heat transfer augmentation or reduction, which is strongly depending on the physical parameters, especially the Darcy number and thermal diffusivity ratio.