TRANSIENT AND STEADY BUOYANCY-DRIVEN FLOW IN A HORIZONTAL CYLINDER

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.