Mixing in Stratified Jets

Experiments were performed to measure the mixing characteristics of turbulent momentum jets discharged horizontally into a linearly-stratified, stationary environment. These flows can occur when sewage is discharged into water bodies such as lakes. The centerline dilution was found to follow the results for an unstratified jet up to the point where the jet begins to collapse under the influence of the stratification. The distance at which this occurs is slightly longer than that reported previously from visual observations. The dilution then continues to increase with distance, but more slowly. The results are interpreted in terms of stratified turbulence collapse, and a model is proposed for the initial and final collapse of the turbulence in the jet. Implications for mixing zone models are discussed.