Velocity profiles and friction coefficients in circular open channels / Ji-In Yoon in Journal of hydraulic research, Vol. 50 N° 3 (Mai/Juin 2012)  

Public ISBD [article]  inJournal of hydraulic research > Vol. 50 N° 3 (Mai/Juin 2012) . - pp. 304-311 Titre : Velocity profiles and friction coefficients in circular open channels Type de document : texte imprimé Auteurs : Ji-In Yoon, Auteur ; Jaeyong Sung, Auteur ; Myeong Ho Lee, Auteur Année de publication : 2012 Article en page(s) : pp. 304-311 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Chézy equation Circular open channel Friction coefficient Manning Stereoscopic PIV Velocity distribution function Résumé : Velocity distributions and friction coefficients in a circular open channel have been investigated experimentally. To measure three-dimensional velocity components, a stereoscopic particle image velocimetry system was used. Based on the measured data, velocity distributions and wall friction coefficients were obtained using the non-linear least-squares fitting method. Unlike in rectangular channels, the velocity distribution varies significantly since the side walls affect the flow in a different manner as the flow depth changes. The present experimental data exhibit different characteristics whether the flow depth is higher or lower than 50% of the pipe diameter. The main effect of the flow depth on the velocity distribution is the ratio of mean to maximum velocities and the position of maximum velocity. Both values reduce if the flow depth is below 50%. Wall friction and Manning coefficients also differ from the generally estimated values as the flow depth is reduced by 50%. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/full/10.1080/00221686.2012.673745 [article] Velocity profiles and friction coefficients in circular open channels [texte imprimé] / Ji-In Yoon, Auteur ; Jaeyong Sung, Auteur ; Myeong Ho Lee, Auteur . - 2012 . - pp. 304-311. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 3 (Mai/Juin 2012) . - pp. 304-311 Mots-clés : Chézy equation Circular open channel Friction coefficient Manning Stereoscopic PIV Velocity distribution function Résumé : Velocity distributions and friction coefficients in a circular open channel have been investigated experimentally. To measure three-dimensional velocity components, a stereoscopic particle image velocimetry system was used. Based on the measured data, velocity distributions and wall friction coefficients were obtained using the non-linear least-squares fitting method. Unlike in rectangular channels, the velocity distribution varies significantly since the side walls affect the flow in a different manner as the flow depth changes. The present experimental data exhibit different characteristics whether the flow depth is higher or lower than 50% of the pipe diameter. The main effect of the flow depth on the velocity distribution is the ratio of mean to maximum velocities and the position of maximum velocity. Both values reduce if the flow depth is below 50%. Wall friction and Manning coefficients also differ from the generally estimated values as the flow depth is reduced by 50%. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/full/10.1080/00221686.2012.673745

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