Jets and plumes with negative or reversing buoyancy

摘要: The motion of turbulent jets heavy salt solution injected upwards into a tank fresh water has been compared with that plumes which are initially buoyant but become as they mix the environment. reversal buoyancy in latter case is produced by using fluids having non-linear density change on mixing, laboratory analogue changes occurring at top cumulus cloud due to evaporation. behaviour two cases quite different; reach steady height about only small fluctuations occur, while reversing exhibit violent regular oscillations. This phenomenon, clearly property ‘evaporation’ and not just geometry, suggested likely explanation observed oscillation tops towers. Dimensional arguments have used relate experimental results volume, momentum fluxes source. An application one deduced relations atmosphere gives realistic periods for cloud-top