The effect of background turbulence on jet entrainment: an experimental study of a plane jet in a shallow coflow

Many effluents are released into water bodies or into the atmosphere, and dilution is relied on to minimize the toxic effects of the pollutants on the environment. Dilution occurs due to entrainment and subsequent mixing of the "clean" (or cleaner) ambient fluid and the effluent stream. In...

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Veröffentlicht in:Journal of hydraulic research Jg. 42; H. 5; S. 533 - 542
Hauptverfasser: Gaskin, S.J., Mckernan, M., Xue, F.
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Delft Taylor & Francis Group 01.01.2004
International Association for Hydraulic Research
Schlagworte:
Background turbulence
coflow
Earth sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
entrainment
Exact sciences and technology
Hydrology
Hydrology. Hydrogeology
jet
Pollution, environment geology
turbulent diffusion
experimental studies
models
diffusion
plumes
effluents
concentration
velocity
pollution
turbulence
buoyancy
pollutants
hydraulics
dilution
direction
ISSN:0022-1686, 1814-2079
Online-Zugang:Volltext
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Zusammenfassung:Many effluents are released into water bodies or into the atmosphere, and dilution is relied on to minimize the toxic effects of the pollutants on the environment. Dilution occurs due to entrainment and subsequent mixing of the "clean" (or cleaner) ambient fluid and the effluent stream. In the near field, dilution occurs due to momentum or buoyancy driven entrainment into the effluent stream, which is proportional to a characteristic velocity of the jet or plume. Whereas in the far field, dilution occurs due to turbulent diffusion at a rate dependent on the level of turbulence in the receiving fluid. In order to predict the expected dilution of an effluent stream, it is necessary to answer the question, at what point does the dilution mechanism change and how does it affect dilution rates. An experimental study examining the velocity and concentration decay of plane jets released into shallow coflows with increasing levels of external turbulence, indicated that levels of external turbulence just large enough to disrupt the jet structure reduced dilution rates significantly. This indicates that models, in which the jet dilution and turbulent diffusion are superimposed, will not always give a conservative estimate of effluent dilution.
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ISSN:0022-1686
1814-2079
DOI:10.1080/00221686.2004.9641222