Modelling three dimensional gravity-induced natural convection buoyant plumes.

The aim of this study was to ascertain the validity of using computational fluid dynamics (CFD) techniques to predict the behaviour of three dimensional gravity induced natural convection buoyant plumes from a vertical heated cylinder in a large quiescent enclosure. The calculated velocity distributions and turbulence quantities over the cylinder were compared to a wide range of experimental measurements. The laminar boundary layer on an isothermal vertical plate was also modelled. The CFX4. l code with the CCCT (QUICK-based) discretisation method and low Reynolds number kE-turbulence model was used. For buoyancy, the Boussinesq approximation was employed. In the calculations, three different sets of boundary conditions were studied. The CFD calculations satisfactorily predicted the boundary layer, velocity profiles, magnitudes and spreading rates of the plume. Good agreement between the CFD predictions for the turbulence intensities and the experimental data was also achieved.