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Title:Spatial signatures of retrograde spanwise vortices in wall turbulence
Author(s):Natrajan, Vinay K.; Wu, Yanhua; Christensen, Kenneth T.
Subject(s):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 Ret = 2350. The present results suggest that a portion of retrograde spanwise vortices have a well-defined spatial relationship with neighboring prograde vortices. Two-point cross-correlations and conditionally averaged velocity fields given a retrograde vortex reveal that such structures are typically oriented either upstream/below or downstream/above a prograde core. While the former preferred orientation is consistent with the typical-eddy patterns reported by Falco and co-workers, we offer an alternative interpretation for a portion of these retrograde/prograde pairs. In particular, the arrangement of a retrograde core upstream and below of 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.
Issue Date:2006-04
Publisher:Department of Theoretical and Applied Mechanics (UIUC)
Series/Report:TAM Reports 1091, (2006)
Genre:Technical Report
Publication Status:published or submitted for publication
Peer Reviewed:is peer reviewed
Date Available in IDEALS:2007-03-09
Is Version Of:Published as: V. K. Natrajan, Y. Wu and K. T. Christensen. Spatial signatures of retrograde spanwise vortices in wall turbulence. Journal of Fluid Mechanics. Vol. 574, 2007, pp. 155-167. DOI: 10.1017/S0022112006003788. Copyright 2007 Cambridge University Press.

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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