Temperature dissipation fluctuations in a turbulent boundary layer

K. R. Sreenivasan, R. A. Antonia, H. Q. Danh

Research output: Contribution to journalArticle

Abstract

All three components of the dissipation rate of the fluctuating temperature θ are measured simultaneously in the inner region of a fully developed turbulent boundary layer at a moderate Reynolds number. Measurements are made with a probe of four cold wires consisting of two closely spaced parallel vertical wires mounted a small distance upstream of two closely spaced parallel horizontal wires. In the inner region of the layer, local isotropy is not closely approximated [(∂θ/θz) 2 >(∂ θ/∂y) 2 >(∂θ/∂x) 2]. The spectral density of the sum χ[ = (∂θ/∂x) 2 + (∂θ/∂y) 2 +(∂θ/∂z) 2] is similar in shape to that of (∂θ/∂y) 2 or (∂θ/∂z) 2 , but not as rich in high frequency content as that of (∂θ/∂x) 2. The probability density of χ has a lower skewness and flatness factor and is more closely log-normal than those of the individual components. This is true regardless of whether χ and its components are unaveraged or locally averaged over a linear dimension r. When averaging is applied, departures from log-normality are diminished but do not disappear entirely. The variance σ 2 of the logarithm of the locally averaged χ is proportional to 1n r over a wide range of r (r max/r min≃30), in contrast to the individual components where this ratio may be as small as 2. The value of the Kolmogoroff constant μ θdetermined from the slope of σ 2 vs 1n r is about 0.35. This is consistent with the slope of the spectral density of χ and is also in agreement with previous best estimates of μ θ(and μ) obtained at high Reynolds numbers.

Original languageEnglish (US)
Pages (from-to)1238-1249
Number of pages12
JournalPhysics of Fluids
Volume20
Issue number8
StatePublished - 1977

Fingerprint

turbulent boundary layer
Boundary layers
dissipation
Spectral density
Wire
Reynolds number
wire
slopes
normality
Temperature
temperature
skewness
high Reynolds number
isotropy
flatness
logarithms
upstream
probes
estimates

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Mechanics of Materials
  • Computational Mechanics
  • Fluid Flow and Transfer Processes

Cite this

Temperature dissipation fluctuations in a turbulent boundary layer. / Sreenivasan, K. R.; Antonia, R. A.; Danh, H. Q.

In: Physics of Fluids, Vol. 20, No. 8, 1977, p. 1238-1249.

Research output: Contribution to journalArticle

Sreenivasan, KR, Antonia, RA & Danh, HQ 1977, 'Temperature dissipation fluctuations in a turbulent boundary layer', Physics of Fluids, vol. 20, no. 8, pp. 1238-1249.
Sreenivasan, K. R. ; Antonia, R. A. ; Danh, H. Q. / Temperature dissipation fluctuations in a turbulent boundary layer. In: Physics of Fluids. 1977 ; Vol. 20, No. 8. pp. 1238-1249.
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