Reynolds number trend of hierarchies and scale interactions in turbulent boundary layers

Baars, W, Hutchins, N and Marusic, I 2017, 'Reynolds number trend of hierarchies and scale interactions in turbulent boundary layers', Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 375, no. 2089, pp. 1-18.


Document type: Journal Article
Collection: Journal Articles

Title Reynolds number trend of hierarchies and scale interactions in turbulent boundary layers
Author(s) Baars, W
Hutchins, N
Marusic, I
Year 2017
Journal name Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume number 375
Issue number 2089
Start page 1
End page 18
Total pages 18
Publisher The Royal Society Publishing
Abstract Small-scale velocity fluctuations in turbulent boundary layers are often coupled with the larger-scale motions. Studying the nature and extent of this scale interaction allows for a statistically representative description of the small scales over a time scale of the larger, coherent scales. In this study, we consider temporal data from hot-wire anemometry at Reynolds numbers ranging from Re-tau approximate to 2800 to 22 800, in order to reveal how the scale interaction varies with Reynolds number. Large-scale conditional views of the representative amplitude and frequency of the small-scale turbulence, relative to the large-scale features, complement the existing consensus on large-scale modulation of the small-scale dynamics in the near-wall region. Modulation is a type of scale interaction, where the amplitude of the small-scale fluctuations is continuously proportional to the near-wall footprint of the large-scale velocity fluctuations. Aside from this amplitude modulation phenomenon, we reveal the influence of the large-scale motions on the characteristic frequency of the small scales, known as frequency modulation. From the wall-normal trends in the conditional averages of the small-scale properties, it is revealed how the near-wall modulation transitions to an intermittent-type scale arrangement in the log-region. On average, the amplitude of the small-scale velocity fluctuations only deviates from its mean value in a confined temporal domain, the duration of which is fixed in terms of the local Taylor time scale. These concentrated temporal regions are centred on the internal shear layers of the large-scale uniform momentum zones, which exhibit regions of positive and negative stream-wise velocity fluctuations. With an increasing scale separation at high Reynolds numbers, this interaction pattern encompasses the features found in studies on internal shear layers and concentrated vorticity fluctuations in high-Reynolds- number wall turbulence.
Subject Aerodynamics (excl. Hypersonic Aerodynamics)
Keyword(s) Amplitude and frequency modulation
Coherent structures
Scale interaction
Wall-bounded turbulence
DOI - identifier 10.1098/rsta.2016.0077
Copyright notice © 2017 The Author(s) Published by the Royal Society. All rights reserved.
ISSN 1364-503X
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 19 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 0 times in Scopus Article
Altmetric details:
Access Statistics: 3 Abstract Views  -  Detailed Statistics
Created: Thu, 23 May 2019, 08:44:00 EST by Catalyst Administrator
© 2014 RMIT Research Repository • Powered by Fez SoftwareContact us