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Fifth International Symposium on Turbulence and Shear Flow Phenomena
August, 27-29, 2007, Technische Universität München, Munich, Germany

DOI: 10.1615/TSFP5

INVESTIGATION OF FINE SCALE STRUCTURES IN A TURBULENT JET BY USING CINEMATOGRAPHIC PARTICLE IMAGE VELOCIMETRY

pages 253-258
DOI: 10.1615/TSFP5.380
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Краткое описание

Cinematographic stereoscopic PIV measurements were performed to resolve small- and intermediate-scales in the far field of an axisymmetric co-owing jet. Measurements were performed in a plane normal to the axis of the jet and the time-resolved measurement was converted to quasiinstantaneous three-dimensional data by using Taylor's hypothesis. The quasi-instantaneous three-dimensional data enabled computation of all nine components of the velocity gradient tensor over a volume. Iso-surfaces of swirling strength (a vortex identification parameter) in the volume reveal that, in agreement with direct numerical simulation results, the intense vortex structures are in the form of elongated 'worms' with characteristic diameter of approximately 10ν and characteristic length of 60−100ν. Iso-surfaces of intense dissipation show that the most dissipative structures are in the form of sheets and are associated with clusters of vortex tubes. The largest length scale of dissipation sheets is of order 60ν and the characteristic thickness (in a plane normal to the axis of the sheet) is about 10ν.

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