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Plane turbulent buoyant jets. Part 2. Turbulence structure

Published online by Cambridge University Press:  12 April 2006

Nikolas E. Kotsovinos
Nikolas E. Kotsovinos
Affiliation:
W. M. Keck Laboratory of Hydraulics and Water Resources, California Institute of Technology, Pasadena Present address: School of Engineering, University of Patras, Greece.
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Abstract

The turbulence structure of a plane vertical buoyant jet in the transition state from jet-like to plume-like growth is the object of this investigation. The ambient fluid is of uniform density and motionless except for the flow induced by the jet.

An analysis of the turbulence energy equation reveals that the production of turbulent energy by the buoyancy forces relative to the production by the shear stress increases as the jet Richardson number increases, and becomes constant for a plume-like buoyant jet.

A systematic set of experiments was carried out to examine the turbulence structure for a wide range of initial Richardson numbers, extending from a value appropriate to a jet-like flow (very close to zero) to that appropriate for a plume-like flow (approximately 0·6). Fast-response thermistors and a laser-Doppler velocimeter were used to measure the buoyant jet's temperature and velocity respectively. The temperature and velocity data were recorded magnetically in digital form and subsequently processed to extract both mean and fluctuating values. The turbulence intensity and the probability density distribution of the temperature and velocity fluctuations, the maximum and minimum temperature, the intermittency, and the frequency of crossing of the hot/cold and the cold/hot interface of a buoyant jet were investigated. It was determined that the intensity of temperature and velocity fluctuations increases with increasing Richardson number. An explanation is suggested for the large-scale vortices observed in a plume.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 81 , Issue 1 , 9 June 1977 , pp. 45 - 62
Copyright
© 1977 Cambridge University Press

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References

Abraham, G. 1963 Jet diffusion in stagnant ambient fluid. Delft Hydraul. Lab. Publ. no. 29.Google Scholar
Batchelor, G. K. 1954 Heat convection and buoyancy effects in fluids. Quart. J. Roy. Met. Soc. 80, 339–358.Google Scholar
Bradbury, L. 1965 The structure of the self-preserving turbulent plane jet. J. Fluid Mech. 23, 31–64.Google Scholar
Brooks, N. H. & Koh, R. C. Y. 1965 Discharge of sewage effluent from a line source into a stratified ocean. 11th Cong. Int. Assoc. Hydraul. Res. paper 2.19.
Hegge Zijnen, B. G. Van Der 1957 Measurements of turbulence in a plane jet of air by the diffusion method and by the hot-wire method. Appl. Sci. Res. 7, 292–313.Google Scholar
Heskestad, G. 1965 Hot wire measurements in a plane turbulent jet. J. Appl. Mech. 33, 721–734 (erratum, Sept. 1966 p. 710).Google Scholar
Kotsovinos, N. E. 1975 A study of the entrainment and turbulence in a plane buoyant jet. W. M. Keck Lab. Hydraul. Water Res., Caltech Rep. KH-R-32.Google Scholar
Kotsovinos, N. E. & List, E. J. 1977 Turbulent buoyant jets. Part 1. Integral properties. J. Fluid Mech. 81, 25–44.Google Scholar
Laufer, J. 1975 New trends in experimental turbulence research. Ann. Rev. Fluid Mech. 7, 307–326.Google Scholar
Lee, S. L. & Emmons, H. W. 1961 A study of natural convection above a line fire. J. Fluid Mech. 11, 353–368.Google Scholar
List, E. J. & Imberger, J. 1973 Turbulent entrainment in buoyant jets and plumes. J. Hydraul. Div. A.S.C.E. 99, 1461–1474.Google Scholar
List, E. J. & Imberger, J. 1975 Concluding discussion of paper ‘Turbulent entrainment in buoyant jets and plumes.’ J. Hydraul. Div. A.S.C.E. 101, 617–620.Google Scholar
Morton, B. R. 1959 Forced plumes. J. Fluid Mech. 5, 151–163.Google Scholar
Morton, B., Taylor, G. I. & Turner, J. S. 1956 Turbulent gravitational convection from maintained and instantaneous sources. Proc. Roy. Soc. A 234, 1–23.Google Scholar
Papailiou, D. D. & Lykoudis, P. S. 1974 Turbulent vortex streets and the entrainment mechanism of the turbulent wake. J. Fluid Mech. 62, 11–31.Google Scholar
Ricou, F. P. & Spalding, D. B. 1961 Measurements of entrainment by axisymmetrical turbulent jets. J. Fluid Mech. 11, 21–32.Google Scholar
Rouse, H., Yih, C. & Humphreys, H. 1952 Gravitational convection from a boundary source. Tellus 4, 200–210.Google Scholar
Shaughnessy, E. 1975 Measurement of particle diffusion in a turbulent jet by laser light scattering. Ph.D. thesis, University of Virginia.