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Investigations of round vertical turbulent buoyant jets

Papanicolaou, Panos N. and List, E. John (1988) Investigations of round vertical turbulent buoyant jets. Journal of Fluid Mechanics, 195 . pp. 341-391. ISSN 0022-1120. doi:10.1017/S0022112088002447.

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The axial and radial velocity components w and u, and the concentration c of a Rhodamine 6G dye were measured simultaneously in a turbulent buoyant jet, using laser-Doppler anemometry combined with a recently developed laser-induced-fluorescence concentration measurement technique. These non-intrusive techniques enable measurements in a region of plume motion where conventional probe-based techniques have had difficulties. The results of the study show that the asymptotic decay laws for velocity and concentration of a tracer transported by the flow are verified experimentally in both jets and plumes. The momentum and volume fluxes and the mean dilution factor are determined in dimensionless form as a function of the normalized distance from the flow source. Contradictory results from earlier experimental plume investigations concerning the decay laws of w and c and the plume width ratio b_c/b_w are discussed. The turbulence properties and the transition from momentum-driven jets to buoyancy-driven plumes are presented. The turbulence is found to scale with the mean flow as predicted by dimensional analysis and self-similarity. Buoyancy-produced turbulence is found to transport twice as much tracer as jet turbulence. Although velocity statistics in jets and plumes are found to be highly self-similar there is a strong disparity in the distribution of tracer concentration in the two flows. This occurs in the time-average mean flows as well as the r.m.s. turbulent quantities. Instantaneous concentration fluctuations are found to exceed time averages by as much as a factor of 3. The experimental results should provide a reasonable basis for validation of computer models of axisymmetric plumes.

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Additional Information:© 1988 Cambridge University Press. (Received 3 April 1987 and in revised form 16 February 1988) The support of the National Science Foundation through Grant Nos. CEE81-17272A01 and MSM84-12641A01 is gratefully acknowledged.
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NSFCEE81-17272 A01
NSFMSM84-12641 A01
Record Number:CaltechAUTHORS:20160418-152319876
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Official Citation:Panos N. Papanicolaou and E. John List (1988). Investigations of round vertical turbulent buoyant jets. Journal of Fluid Mechanics, 195, pp 341-391 doi:10.1017/S0022112088002447
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66258
Deposited By: George Porter
Deposited On:18 Apr 2016 22:33
Last Modified:10 Nov 2021 23:55

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