Flow resistance over fixed roughness elements / Yang, Shu-Qing in Journal of hydraulic research, Vol. 49 N° 2 (Mars/Avril 2011)  

Public ISBD [article]  inJournal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 257-262 Titre : Flow resistance over fixed roughness elements Type de document : texte imprimé Auteurs : Yang, Shu-Qing, Auteur ; Yu Han, Auteur ; Nadeesha Dharmasiri, Auteur Année de publication : 2011 Article en page(s) : pp. 257-262 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Friction factor Open channel flow Pipe Reynolds number Turbulent Index. décimale : 627 Ingénierie des cours d'eau naturels, des ports, des rades et des cotes. Installations de navigation, de dragage, de récupération et de sauvetage. Barrages et centrales électriques hydrauliques Résumé : The underlying mechanism of flow resistance in open channels and pipelines over rough boundary is investigated. Different from Einstein's method, this work extends the principle of boundary shear stress summation in a mobile bed to the rigid boundary. It is found that the principle is valid to express the friction factor in all pipe flow regimes, mainly concerning the transition from laminar to turbulent flows, and between fully smooth and fully rough turbulent flows. This research also evaluates the concept developed by Einstein regarding the relationship between skin friction and form drag. Experimental data of Nikuradse are used to test the obtained results, indicating that the above-mentioned method yields the best agreement with experimental data, relative to the other friction factor formulas available in the literature. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.540121 [article] Flow resistance over fixed roughness elements [texte imprimé] / Yang, Shu-Qing, Auteur ; Yu Han, Auteur ; Nadeesha Dharmasiri, Auteur . - 2011 . - pp. 257-262. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 257-262 Mots-clés : Friction factor Open channel flow Pipe Reynolds number Turbulent Index. décimale : 627 Ingénierie des cours d'eau naturels, des ports, des rades et des cotes. Installations de navigation, de dragage, de récupération et de sauvetage. Barrages et centrales électriques hydrauliques Résumé : The underlying mechanism of flow resistance in open channels and pipelines over rough boundary is investigated. Different from Einstein's method, this work extends the principle of boundary shear stress summation in a mobile bed to the rigid boundary. It is found that the principle is valid to express the friction factor in all pipe flow regimes, mainly concerning the transition from laminar to turbulent flows, and between fully smooth and fully rough turbulent flows. This research also evaluates the concept developed by Einstein regarding the relationship between skin friction and form drag. Experimental data of Nikuradse are used to test the obtained results, indicating that the above-mentioned method yields the best agreement with experimental data, relative to the other friction factor formulas available in the literature. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.540121

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