Flow time scales and drag reduction

The effects of the flow time scales on the onset and magnitude of drag reduction in turbulent pipe flow were studied using comparatively low molecular weight samples of water soluble polymers in glycerine‐water mixtures and in two different pipe sizes. The results show that onset depends only on the...

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Bibliographic Details
Published in:The Physics of fluids (1958) 1977-10, Vol.20 (10), p.S168-S174
Main Author: Berman, Neil S.
Format: Article
Language:English
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Summary:The effects of the flow time scales on the onset and magnitude of drag reduction in turbulent pipe flow were studied using comparatively low molecular weight samples of water soluble polymers in glycerine‐water mixtures and in two different pipe sizes. The results show that onset depends only on the time scale νu τ 2 with no Reynolds number dependence. The magnitude of drag reduction after the molecules are extended was found to increase with pipe diameter. A correlation with the lifetime of large eddies or the mean period of turbulence production is suggested.
ISSN:0031-9171
2163-4998
DOI:10.1063/1.861726