On the vorticity dynamics of a turbulent jet in a crossflow

We present numerical solutions of the fully three-dimensional flow of a round, turbulent jet emitted normal to a uniform free stream. Comparisons with available laboratory data and comparison between different numerical grid resolutions are used to demonstrate the quality of the simulation. Examination of the detailed flow pattern within a computational domain, which extends 15 jet diameters from the source allows us to follow the vorticity dynamics in the transition from an initially vertical jet to a wake with a vortex pair essentially aligned with the free stream. The transition is presented as a function of the ratio of the jet exit velocity to free stream velocity. For large velocity ratios, the source of the streamwise vorticity in the vortex pair can be readily traced back to the original streamwise vorticity in the sides of the vertical jet.