Abstract
We have performed three-dimensional linear stability analyses for natural convection in concentric annuli with porous media. A constant heat flux is given at the inner cylinder, while the outer cylinder surface is maintained a constant temperature. We calculate the critical Rayleigh numbers when the basic two-dimensional flow becomes unstable with respect to three-dimensional disturbances. Additionally, we measure a local Nusselt Number to examine the heat transfer characteristics when we put both water and porous media in the gap of two concentric cylinders. In addition, we compare the convection flow patterns obtained from visualization with the results from stability analyses.
