Mixing Behavior of Absolutely Unstable Axisymmetric Shear Layers Forming Side Jets.
Mixing Behavior of Absolutely Unstable Axisymmetric
Shear Layers Forming Side Jets.
Pitts, W. M.; Johnson, A. W.
IUTAM Symposium. Variable Density Low Speed Turbulent
Flows. Volume 41. Fluid Mechanics and Its
Applications. 1997, Kluwer Academic Publishers,
Fulachier, L.; Lumley, J. L.; Anselmet, F.,
Editor(s)(s), 17-24 pp, 1997.
absolute instability; axisymmetric jets; concentration
measurement; mixing; Raleigh light scattering; side jets
Recently it has been shown that low-density axisymmetric
jets can become absolutely unstable and develop highly
coherent vortical structures in the near-field shear
layer. These jets have several unusual properties when
compared to jets which are convectively unstable. The
vortical structures grow quickly with downstream
distance and rapidly develop three-dimensional
structure. Intense pairing of alternative structures is
observed. Perhaps the most interesting of all behaviors
is the observation of strong ejections of jet fluid,
termed "side jets", into the ambient surroundings.
Their formation is attributed to the generation of
strongly coupled pairs of lontiudinal vortices in the
developing shear layer.