Velocity measurements of turbulence collapse in a linearly stratified jet

The behavior of a horizontal turbulent round jet in a linearly density-stra tified fluid is studied and compared to the unstratified case using digital particle-tracking velocimetry (DPTV). Close to the nozzle, the stratified jet grows axi symmetrically at the same rate as an unstratified jet. At a c ritical distance downstream, the vertical growth is suppressed, while the l ateral spreading increases. The self-similar nature of unstratified round j ets is not preserved in the stratified case. The velocity field and turbule nt stresses are affected by the stratification closer to the jet nozzle tha n is expected from the flow visualization observations. In particular, the vertical normal stress and shear stress are significantly reduced compared to the unstratified case.