The ASTEC code is used to simulate both transient and steady two-dimen
sional, compressible, buoyancy-driven laminar flow and heat transfer i
n a horizontal cylinder full of air. Calculations cover Rayleigh numbe
rs from 10(4) to 10(8). The local and average Nusselt numbers, the vel
ocity and temperature profiles along the vertical and horizontal diame
ters, and the velocity vector plots and temperature fields are present
ed for both the transient and steady-state cases. Results show that a
near-stagnant, thermally stratified core exists only at moderately hig
h Rayleigh numbers (> 10(5)), the dimensionless temperature difference
vertically across the core decreases with increasing Rayleigh number,
and the time evolution of the flow and thermal fields is quite compli
cated. Numerical predictions are in good agreement with available expe
rimental data.