University of Illinois Urbana-Champaign

Spatial signatures of retrograde spanwise vortices in wall turbulence

Natrajan, Vinay K.; Wu, Yanhua; Christensen, Kenneth T.

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https://hdl.handle.net/2142/1712

Description

Title
Spatial signatures of retrograde spanwise vortices in wall turbulence
Author(s)
  • Natrajan, Vinay K.
  • Wu, Yanhua
  • Christensen, Kenneth T.
Issue Date
2007
Keyword(s)
  • Vortices
  • Wall turbulence
Abstract
The spatial signatures of retrograde spanwise vortices in wall turbulence are assessed from particle-image velocimetry measurements in the streamwise–wall-normal plane of a zero-pressure-gradient turbulent boundary layer at Reτ ≡u∗δ/ν =2350. The present results suggest that a proportion of retrograde spanwise vortices have a welldefined spatial relationship with neighbouring prograde vortices. Two-point crosscorrelations and conditionally averaged velocity fields given a retrograde vortex reveal that such structures are typically oriented either upstream of and below or downstream of and above a prograde core. While these pairings are consistent with the typical-eddy patterns reported by Falco and co-workers, we offer an alternative interpretation for a proportion of these retrograde/prograde pairs. In particular, the arrangement of a retrograde spanwise vortex upstream of and below a prograde core is also consistent with the spatial signature revealed if an omega-shaped hairpin structure were sliced through its shoulder region by a fixed streamwise–wall-normal measurement plane.
Publisher
Cambridge University Press
Type of Resource
text
Language
en
Permalink
http://hdl.handle.net/2142/1712
DOI
https://doi.org/10.1017/S0022112006003788
Copyright and License Information
Copyright owned by Cambridge University Press 2007.

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Published Papers - Theoretical and Applied Mechanics (TAM) PRIMARY
Papers published by faculty in Theoretical and Applied Mechanics