Measurement of the turbulent diffusivity in the near field of variable density jets using conditional velocimetry

Pulsed laser Mie scattering and laser Doppler velocimetry (LDV), both conditioned on the origin of the seed particles, have been successively performed in turbulent jets with variable density. In the early stages of the jet developments, significant differences are measured between the ensemble aver...

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Bibliographic Details
Published in:Experiments in fluids 2003-11, Vol.35 (5), p.397-407
Main Authors: Stepowski, D, Sautet, J C
Format: Article
Language:English
Subjects:
Computational fluid dynamics
Density
Fluid flow
Markers
Nucleation
Turbulence
Turbulent flow
Velocimetry
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Summary:Pulsed laser Mie scattering and laser Doppler velocimetry (LDV), both conditioned on the origin of the seed particles, have been successively performed in turbulent jets with variable density. In the early stages of the jet developments, significant differences are measured between the ensemble average LDV data obtained by jet seeding and those obtained by seeding the ambient air. Careful analysis of the marker statistics shows that this difference is a quantitative measure of the turbulent mixing. The good agreement with gradientadiffusion modelling suggests the validity of a general diffusion equation where the velocities involved are expressed in terms of ensemble conditional Favre averages. This operator accounts for all events (including intermittent ones) and for variations in the density of the marked fluid whose velocity is still specified by the binary origin of the marker.
ISSN:0723-4864
1432-1114
DOI:10.1007/s00348-003-0662-5