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Rough-wall turbulent boundary layers in the transition regimeAn experimental investigation of turbulent boundary layers over two-dimensional spanwise groove and three-dimensional sandgrain roughnesses in the transition regime between hydraulically smooth and fully rough conditions is presented. It is found that a self-preserving state can be reached in boundary layers developing over both d-type groove and sandgrain roughnesses, and that the drag of a k-type rough wall can be reduced by lowering the spanwise aspect ratio of the roughness elements. The two roughness Reynolds numbers defining the boundaries of the transition regime of the k-type roughnesses are shown to decrease with increasing roughness-element spanwise aspect ratio, and the upper critical transition Reynolds number is shown to determine the roughness behavior in both the transition and fully rough regime.
Document ID
19870063031
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bandyopadhyay, Promode R.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 13, 2013
Publication Date
July 1, 1987
Publication Information
Publication: Journal of Fluid Mechanics
Volume: 180
ISSN: 0022-1120
Subject Category
Fluid Mechanics And Heat Transfer
Accession Number
87A50305
Funding Number(s)
CONTRACT_GRANT: NAS1-17296
Distribution Limits
Public
Copyright
Other

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