An approach to the simulation of natural-convective heat transfer between two concentric horizontal cylindrical annuli

The effects of Rayleigh and Prandtl number, diameter, and temperature difference ratio in the ranges 10(2) <= Ra <= 10(5), 10(-3) e Pr <= 10(-3), 0.8 <= L <= 2.0, and 0 <= J e 2.0, respectively on the heat function in a concentric horizontal cylindrical annulus are investigated numerically. The results show that heat transfer in a cylindrical annulus is enhanced by making the gap width smaller than the cylinder inner radius. Both the Rayleigh and Prandtl numbers and the temperature difference ratio have very strong effects on the heat function profiles.