A LARGE-EDDY SIMULATION OF BUOYANT PLUMES IN A CONVECTIVE BOUNDARY-LAYER

By means of a large-eddy simulation technique, the time-dependent large-scale flow field of a convective atmospheric boundary layer has been claculated. Using a conservation equation for the concentration dispersion we applied this simulation technique to dispersion from both passive and buoyant sources. The results were found to be in good agreement with laboratory and field experiments. It was possible to separate the mean plume motion into a part induced by convective turbulence and a part induced by plume buoyancy. We found that the part of the plume motion caused by convective turbulence was strongly influenced by plume buoyancy. On the other hand, it appears that the large-scale motions of convective turbulence have a strong influence on the entrainment processes governing the motion due to buoyancy. © 1990 Società Italiana di Fisica.