The influence of a localised region of turbulence on the structural development of a turbulent, round, buoyant jet

Results are presented from a series of laboratory experiments in which the interaction of a turbulent buoyant jet with a localised patch of grid-generated turbulence has been investigated. The experiments show that the effect of the turbulent patch is to arrest the structural development of the buoyant jet at a location determined by the relative values of the r.m.s. turbulent velocities in the patch and jet, respectively. Measurements of the breakdown distance z c from the jet source have been compared successfully with the predictions of a scaling analysis for the limiting cases of momentum- and buoyancy-dominated regions of the buoyant jet.