Vortex Flows and Related Numerical Methods II
ESAIM: Proceedings,
Vol. 1, 1996, pp. 553-564
Three-Dimensional Vorticity Dynamics in a
Coflowing Turbulent Jet Subjected to
Axial and Azimuthal Perturbations
Katherine Prestridge and Juan C. Lasheras
Department of Applied Mechanics and Engineering Sciences
University of California, San Diego
La Jolla, CA 92093-0411, USA
Abstract
The effect of axial and azimuthal forcing on the spreading and mixing
characteristics in the near field x/D<13 of a
coflowing, turbulent Re>2000 water jet is studied by means
of planar, laser induced fluorescence (PLIF) visualizations.
Measurements of both the initial spreading rate of the jet and the
decay of the concentration along the centerline of the jet show a
marked increase in the mixing of the jet as a result of the axial
forcing. The mixing enhancement, which is shown to depend on the
wavenumber of the azimuthal forcing, the frequency of the axial forcing,
and the Reynolds number of the jet, results from the formation of
vortex loops caused by the global induction of the jet's vorticity.
This vortex induction mechanism appears to be similar to the
vorticity modes earlier found in laminar coflowing jets (Lasheras et
al., Lect. Appl. Math., 28, 1991).
Vortex Flows and Related
Numerical Methods II
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