Flow structures in initial region of two interacting parallel plane jets

The initial region of two interacting parallel plane jets with a truncated bluff body at the plane of symmetry is studied with velocity measurements in the frequency and time domains. The mean flows of the two plane jets are nearly parallel to the plane of symmetry, and their inner and outer mixing regions are found. Within these mixing regions their respective trains of coherent structures, which are of vortical form, are established. The inner vortices are inwardly rotational, while the outer vortices rotate outwardly. The successive initial vortices in the inner mixing region seem to undergo two processes of either pairing or amalgamation. The former results in the formation of a nearly circular coherent structure, while the latter results in the elongated structure. Both the inner and other structures experience fairly rapid decay. The process of decay also seems to be either the usual decay or the division of the coalesced structure back into the individual vortical structures followed by their decay.