Correlation of frictional drag and roughness length scale for transitionally and fully rough turbulent boundary layers

Uʇur Oral Ünal*

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21 Atıf (Scopus)

Özet

This study investigates zero-pressure-gradient turbulent boundary layers for several rough surfaces in the transitionally rough and fully rough flow regimes. The tested surfaces include, but are not limited to marine antifoulings as irregularly rough engineering surfaces. The boundary layer profiles were measured by using a two-dimensional Laser Doppler Velocimetry system. The coatings were applied with different procedures to simulate the effect of different application types. An attempt was made to find a new roughness length scale which provides a good correlation to represent the roughness functions for both transitionally and fully rough flow regimes. Surface roughness measurements with a laser profilometer device were carried out to determine several roughness parameters to be used in the calculation of the roughness length scale. Different roughness calculation methods, with varying low-pass filter window lengths and sampling lengths, were applied to determine their effect on the roughness parameters and hence the roughness function correlations. The paper presents a new definition for the roughness length scale and covers the details of the measurements, analyses, discussions regarding the differences between the surfaces, the effect of the roughness calculation methods and application type of the antifouling coatings.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)283-298
Sayfa sayısı16
DergiOcean Engineering
Hacim107
DOI'lar
Yayın durumuYayınlandı - 25 Ağu 2015

Bibliyografik not

Publisher Copyright:
© 2015 Elsevier Ltd. All rights reserved.

Finansman

This research was supported by the Emerson Cavitation Tunnel (School of Marine Science and Technology) of Newcastle University (Grant no: C0570D0306). The coating materials were provided by International Paint Ltd., Gateshead, UK, as a kind contribution to this research study. The author gratefully acknowledges the close collaboration and help provided by the Emerson Cavitation Tunnel staff, in particular Prof. Mehmet Atlar, Mr. Georgios Politis and Dr. Roderick Sampson. The author is also grateful to Dr. Colin Anderson of International Paint Ltd. in materializing the coating needs for the tests. Special thanks are conveyed to Prof. Ömer Gören and Prof. Emin Korkut of Istanbul Technical University for their help during the preparation of this paper.

FinansörlerFinansör numarası
Emerson Cavitation Tunnel
Newcastle UniversityC0570D0306

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