Repository logo
 

Turbulence spectra in the buoyancy subrange of thermally stratified shear flows

Simple item page
dc.contributor.authorLin, Jung-Tai, author
dc.contributor.authorPanchev, S. (Stoĭcho), 1933-, author
dc.contributor.authorCermak, J. E. (Jack E.), author
dc.contributor.authorFluid Dynamics and Diffusion Laboratory, College of Engineering, Colorado State University, publisher
dc.date.accessioned2019-09-17T19:20:11Z
dc.date.available2019-09-17T19:20:11Z
dc.date.issued1969-02
dc.descriptionCER68-69JTL21.
dc.descriptionFebruary 1969.
dc.descriptionOriginally presented as the author's thesis, Colorado State University.
dc.descriptionIncludes bibliographical references (pages 94-97).
dc.descriptionPrepared under Office of Naval Research, project no. NR 062-414/6-6-68(Code 438), U.S. Department of Defense.
dc.description.abstractA generalized eddy-viscosity approximation is used to study the turbulence spectra of thermally stratified shear flows. For a stationary process in the wave number range investigated--the buoyancy subrange--under the assumption of local homogeneity of the flow, two governing spectral equations with six unknowns are derived from the equations of motion and energy. In order to reduce the number of unknowns to two so that the spectral equations can be solved, a generalized eddy-viscosity is used for expressing the integrated forms of the inertial transfers of energy and temperature inhomogeneity, the shear stress and vertical heat flux in terms of velocity spectrum ¢(k) and temperature spectrum ¢TT(k). Asymptotic solutions are obtained in the buoyancy subrange where the local production and local dissipation of turbulent energy is negligible as compared to the inertial transfer and vertical heat flux terms when the flow conditions satisfy the criterion ε|dT'/dz| << N g/T' or g/T'. |dT'/dz| << N/ε.(g/T)^2. In the buoyancy subrange of stably stratified turbulent flow, the power law for the velocity and temperature spectra is not universal but varies with the flow conditions in the way ¢(k) ~ k^n and ¢TT(k) ~ k^m where 11/5 ≥ n ≥ -3 and -1 ≥ m ≥ -7/5. According to the measurements of velocity spectra in the atmosphere (Pinus and Schcherbakova, 1966; Myrup, 1968), the dependence of the power law on the flow conditions was confirmed. The solutions of Bolgiano (1959) and Luialey-Shur (1964) are only two particular cases of the present results under cert ain flow conditions. In the case of the unstably stratified turbulent flow, the velocity spectrum exhibits a hump in the buoyancy subrange as a result of the energy input from the temperature field to the velocity field. In the left side of this hump the velocity spectrum approaches a +1 slope and the temperature spectrum shows a -3 slope. The measurements of the velocity spectra in the atmosphere (Ivanov and Ordanovich, 1967) confirms this tendency.
dc.description.sponsorshipUnder Contract no. N00014-68-A-0493-0001.
dc.format.mediumtechnical reports
dc.identifier.urihttps://hdl.handle.net/10217/198087
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relationCatalog record number (MMS ID): 991012736759703361
dc.relation.ispartofCivil Engineering Reports
dc.relation.ispartofCER, 68/69-21
dc.relation.ispartofProject THEMIS technical report, no. 1
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectHydrodynamics
dc.subjectFluid dynamics
dc.subjectTurbulence
dc.titleTurbulence spectra in the buoyancy subrange of thermally stratified shear flows
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Files

Collections

Civil Engineering Reports