Characterization of structures associated with low- and high-shear regions in experimental and numerical turbulent channel flows

Omid Amili, Yoshinori Mizuno, Nicolas Buchmann, Callum Atkinson, Julio Soria

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

Abstract

Measurements of the wall shear stress distribution in a fully developed turbulent channel flow have been performed using a film-based sensor. The sensor, as a direct method for measuring the wall shear stress, enables the conduction of measurements in a relatively large domain with high spatial resolution. From the experimental data, instantaneous velocity components in the region of y+<5 were approximated using the instantaneous wall shear stress distribution, the application of the continuity condition, and Taylor expansion of the velocity at the wall. In addition, a direct numerical simulation of a turbulent channel flow at the same Reynolds number range was used to assess the experimental results and to extend the analysis to the buffer layer. The investigated Reynolds numbers are in the range of 2,100-2,900 based on the friction velocity and the half channel height. The distribution of the fluctuating wall shear stress reveals the presence of low- and high-shear regions oriented in the streamwise direction. This indicates the imprint of existing streaky structures in the near-wall region. The conditionally averaged field of low-shear stress regions exhibits the existence of a counter-rotating vortex pattern elongated in the streamwise direction. The averaged map conjectures the signature of long quasi-streamwise vortices or stretched legs of hairpins as the dominant structures in the immediate vicinity of the wall.

Original languageEnglish
Title of host publicationInternational Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013
PublisherTSFP-8
Volume2
ISBN (Electronic)9780000000002
Publication statusPublished - 1 Jan 2013
EventTurbulence and Shear Flow Phenomena 2013 - École Nationale Supérieure de Mécanique et d'Aérotechnique, Poitiers, France
Duration: 28 Aug 201330 Aug 2013
Conference number: 8th
https://web.archive.org/web/20130403150344/http://tsfp8.pprime.fr/index.php

Conference

ConferenceTurbulence and Shear Flow Phenomena 2013
Abbreviated titleTSFP-8
CountryFrance
CityPoitiers
Period28/08/1330/08/13
OtherThe series of biennial TSFP Symposia is the principal venue for reporting and
disseminating recent and ongoing research on turbulence and shear flow phenomena.
Internet address

Cite this

Amili, O., Mizuno, Y., Buchmann, N., Atkinson, C., & Soria, J. (2013). Characterization of structures associated with low- and high-shear regions in experimental and numerical turbulent channel flows. In International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013 (Vol. 2). TSFP-8.