The University of Southampton
University of Southampton Institutional Repository

Time evolution of uniform momentum zones in a turbulent boundary layer

Time evolution of uniform momentum zones in a turbulent boundary layer
Time evolution of uniform momentum zones in a turbulent boundary layer

Time-resolved planar particle image velocimetry was used to analyse the structuring of a turbulent boundary layer into uniform momentum zones (UMZs). The instantaneous peak-detection method employed by Adrian et al. (J. Fluid Mech., vol. 422, 2000, pp. 1–54) and de Silva et al. (J. Fluid Mech., vol. 786, 2016, pp. 309–331) is extended to account for temporal coherence of UMZs. The resulting number of zones detected appears to follow a normal distribution at any given instant. However, the extreme cases in which the number of zones is either very high or very low, are shown to be linked with two distinct flow states. A higher than average number of zones is associated with a large-scale (Formula presented.) event in the log region which creates increased small-scale activity within that region. Conversely, a low number of zones corresponds to a large-scale (Formula presented.) event in the log region and decreased turbulent activity away from the wall. The residence times, within the measurement plane, of zones belonging to the latter scenario are shown to be on average four times larger than those of zones present during higher than average zone structuring states. For both cases, greater residence times are observed for zones of higher momentum that are generally closer to the free stream.

boundary layer structure, turbulent flows
0022-1120
554-590
Laskari, A.
15fd6017-4699-4cb5-bbf1-a158e8dcd70f
de Kat, R.
d46a99a4-8653-4698-9ef4-46dd0c77ba5d
Hearst, R.J.
965708e6-ddf4-4cbb-af74-866bb4cdb4de
Ganapathisubramani, B.
5e69099f-2f39-4fdd-8a85-3ac906827052
Laskari, A.
15fd6017-4699-4cb5-bbf1-a158e8dcd70f
de Kat, R.
d46a99a4-8653-4698-9ef4-46dd0c77ba5d
Hearst, R.J.
965708e6-ddf4-4cbb-af74-866bb4cdb4de
Ganapathisubramani, B.
5e69099f-2f39-4fdd-8a85-3ac906827052

Laskari, A., de Kat, R., Hearst, R.J. and Ganapathisubramani, B. (2018) Time evolution of uniform momentum zones in a turbulent boundary layer. Journal of Fluid Mechanics, 842, 554-590. (doi:10.1017/jfm.2018.126).

Record type: Article

Abstract

Time-resolved planar particle image velocimetry was used to analyse the structuring of a turbulent boundary layer into uniform momentum zones (UMZs). The instantaneous peak-detection method employed by Adrian et al. (J. Fluid Mech., vol. 422, 2000, pp. 1–54) and de Silva et al. (J. Fluid Mech., vol. 786, 2016, pp. 309–331) is extended to account for temporal coherence of UMZs. The resulting number of zones detected appears to follow a normal distribution at any given instant. However, the extreme cases in which the number of zones is either very high or very low, are shown to be linked with two distinct flow states. A higher than average number of zones is associated with a large-scale (Formula presented.) event in the log region which creates increased small-scale activity within that region. Conversely, a low number of zones corresponds to a large-scale (Formula presented.) event in the log region and decreased turbulent activity away from the wall. The residence times, within the measurement plane, of zones belonging to the latter scenario are shown to be on average four times larger than those of zones present during higher than average zone structuring states. For both cases, greater residence times are observed for zones of higher momentum that are generally closer to the free stream.

Text
Time_evolution_of_Uniform_Momentum_Zones - Accepted Manuscript
Download (6MB)

More information

Accepted/In Press date: 27 January 2018
e-pub ahead of print date: 13 March 2018
Published date: 10 May 2018
Keywords: boundary layer structure, turbulent flows

Identifiers

Local EPrints ID: 420233
URI: http://eprints.soton.ac.uk/id/eprint/420233
ISSN: 0022-1120
PURE UUID: 496aed32-0c1c-4d52-97d9-8131be29b208
ORCID for R. de Kat: ORCID iD orcid.org/0000-0002-6851-4409
ORCID for B. Ganapathisubramani: ORCID iD orcid.org/0000-0001-9817-0486

Catalogue record

Date deposited: 02 May 2018 16:30
Last modified: 07 Oct 2020 06:40

Export record

Altmetrics

Contributors

Author: A. Laskari
Author: R. de Kat ORCID iD
Author: R.J. Hearst

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×