The turbulent Prandtl number in a pure plume is 3/5

File Description SizeFormat 
main.pdfAccepted version649.16 kBAdobe PDFDownload
turbulent_prandtl_number_in_a_pure_plume_is_35.pdfPublished version606.53 kBAdobe PDFDownload
Title: The turbulent Prandtl number in a pure plume is 3/5
Author(s): Craske, J
Salizzoni, P
Van Reeuwijk, M
Item Type: Journal Article
Abstract: We derive a new expression for the entrainment coefficient in a turbulent plume using an equation for the squared mean buoyancy. Consistency of the resulting expression with previous relations for the entrainment coefficient implies that the turbulent Prandtl number in a pure plume is equal to 3 / 5 when the mean profiles of velocity and buoyancy have a Gaussian form of equal width. Entrainment can be understood in terms of the volume flux, the production of turbulence kinetic energy or the production of scalar variance for either active or passive variables. The equivalence of these points of view indicates how the entrainment coefficient and the turbulent Prandtl and Schmidt numbers depend on the Richardson number of the flow, the ambient stratification and the relative widths of the velocity and scalar profiles. The general framework is valid for self-similar plumes, which are characterised by a power-law scaling. For jets and pure plumes it is shown that the derived relations are in reasonably good agreement with results from direct numerical simulations and experiments.
Publication Date: 8-Jun-2017
Date of Acceptance: 27-Mar-2017
URI: http://hdl.handle.net/10044/1/46102
DOI: https://dx.doi.org/10.1017/jfm.2017.259
ISSN: 1469-7645
Publisher: Cambridge University Press (CUP)
Start Page: 774
End Page: 790
Journal / Book Title: Journal of Fluid Mechanics
Volume: 822
Copyright Statement: © 2017 Cambridge University Press This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
Sponsor/Funder: EPSRC
Keywords: Science & Technology
Technology
Physical Sciences
Mechanics
Physics, Fluids & Plasmas
Physics
plumes/thermals
stratified turbulence
turbulent mixing
GRAVITATIONAL CONVECTION
BUOYANT PLUME
ROUND JET
ENTRAINMENT
TEMPERATURE
01 Mathematical Sciences
09 Engineering
Fluids & Plasmas
Publication Status: Published
Appears in Collections:Faculty of Engineering
Civil and Environmental Engineering



Items in Spiral are protected by copyright, with all rights reserved, unless otherwise indicated.

Creative Commons