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Turbulent Mixing in Transverse Jets

Shan, Jerry and Dimotakis, Paul (2001) Turbulent Mixing in Transverse Jets. California Institute of Technology . (Unpublished) http://resolver.caltech.edu/CaltechGALCITFM:2001.006

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Abstract

Turbulent mixing is studied in liquid-phase transverse jets. Jet-fluid concentration fields were measured using laser-induced fluorescence and digital-imaging techniques, for jets in the Reynolds number range 1000 <= Re <= 20,000, at a jet-to-freestream velocity ratio of 10. Analysis of the measured scalar fields indicates that turbulent mixing is Reynolds-number dependent, as manifest in the evolving probability density functions of jet-fluid concentration. Enhanced homogenization is found with increasing Reynolds number. Turbulent mixing is also seen to be flow dependent, based on differences between jets discharging into a crossflow and jets into a quiescent reservoir. A novel technique for whole-field measurement of scalar increments was used to study the distribution of difference (scalar increments) of the scalar field. These scalar increments are found to tend toward exponential-tailed distributions with decreasing separation distance. Finally, the scalar field is found to be anisotropic, particularly at small length scales. This is seen in power spectra, directional scalar microscales, and directional PDFs of scalar increments. The local anisotropy of the scalar field is explained in terms of the global dynamics and large-scale strain field of the transverse jet.


Item Type:Report or Paper (Technical Report)
Group:Graduate Aeronautical Laboratories (Fluid Mechanics)
Subject Keywords:Turbulence, mixing, transverse, jets, laser-induced fluorescence, anisotropy, spatial structure
Record Number:CaltechGALCITFM:2001.006
Persistent URL:http://resolver.caltech.edu/CaltechGALCITFM:2001.006
Usage Policy:You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format.
ID Code:25812
Collection:CaltechGALCITFM
Deposited By: Imported from CaltechGALCITFM
Deposited On:18 Oct 2001
Last Modified:26 Dec 2012 13:48

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