Reynolds stress scaling in pipe flow turbulence-first results from CICLoPE.
This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×104are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A2≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A2,w≈A2/2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'.
Linné FLOW Centre, KTH Mechanics, 10044 Stockholm, Sweden ramis@mech.kth.se.
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http://orcid.org/0000-0002-1663-3553
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Örlü
Department of Industrial Engineering, Alma Mater Studiorum, Università di Bologna, 47100 Forlì, Italy.
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T
Fiorini
Linné FLOW Centre, KTH Mechanics, 10044 Stockholm, Sweden.
A
http://orcid.org/0000-0001-8667-0520
A
Segalini
Department of Industrial Engineering, Alma Mater Studiorum, Università di Bologna, 47100 Forlì, Italy.
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G
Bellani
Linné FLOW Centre, KTH Mechanics, 10044 Stockholm, Sweden.|Department of Industrial Engineering, Alma Mater Studiorum, Università di Bologna, 47100 Forlì, Italy.
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A
Talamelli
Linné FLOW Centre, KTH Mechanics, 10044 Stockholm, Sweden.|Department of Industrial Engineering, Alma Mater Studiorum, Università di Bologna, 47100 Forlì, Italy.
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http://orcid.org/0000-0002-1146-3241
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Alfredsson
high Reynolds number turbulence; pipe flow; wall turbulence