Mixing in stratified jets

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