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Title:Reynolds-stress enhancement associated with a short fetch of roughness in wall turbulence
Author(s):Wu, Yanhua; Christensen, Kenneth T.
Subject(s):Reynolds stress producing events
Abstract:Particle-image velocimetry experiments are performed to study the response of smooth-wall turbulent channel flow to a short fetch of roughness (ten outer length scales long). The roughness studied herein is replicated from a surface scan of a damaged turbine blade and contains both large- and small-scale surface defects attributable to pitting, deposition and spallation. Quadrant analysis is used to investigate the characteristics of Reynolds-stress-producing events within the internal layer that develops over the roughness. The total mean Reynolds stress is dramatically increased in the presence of the roughness as compared to the smooth-wall baseline owing to an increased number of extremely intense ejections and sweeps. In contrast, inward and outward interactions, as well as relatively weak ejection and sweep events, are found to be insensitive to the surface conditions. While the stress and space fractions for all Reynolds-stress-producing events are found to be insensitive to the surface topology, the most intense ejection and sweep events yield stress and space fractions that vary significantly with the local surface topology.
Issue Date:2006-01
Technical Report
Publication Status:published or submitted for publication
Peer Reviewed:is peer reviewed
Date Available in IDEALS:2007-01-18
Is Version Of:Published as: Yanhua Wu and Kenneth T. Christensen. Reynolds-stress enhancement associated with a short fetch of roughness in wall turbulence. AIAA Journal, Vol. 44, No. 12, 2006, pp. 3098-3106. DOI: 10.2514/1.22357. Copyright 2006 American Institute of Aeronautics and Astronautics, Inc.

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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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