Documents disponibles écrits par cet auteur

Comparison of macroturbulence measured using decomposition of PIV, ADV and LSPIV data / James F. Fox in Journal of hydraulic research, Vol. 49 N° 1 (Janvier/Fevrier 2011) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 49 N° 1 (Janvier/Fevrier 2011) . - pp. 122-126 Titre : Comparison of macroturbulence measured using decomposition of PIV, ADV and LSPIV data Type de document : texte imprimé Auteurs : James F. Fox, Auteur ; Brian J. Belcher, Auteur Année de publication : 2011 Article en page(s) : pp. 122-126 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Gravel-bed  Open  channel  Scales  of  turbulence  Velocimetry 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 : Visualization and length-scale estimates are provided for turbulence in open channel flow over a gravel-bed. Results obtained using the digital particle image velocimetry (PIV) followed by post-processing with proper orthogonal decomposition showed higher and lower velocity regions aligned along a stagnation plane extending from the bed at approximately a 20° angle. Periodicity of second and fourth quadrant events equalled 0.20 s and agreed well with the outer variable defined bursting period. Normalized turbulence length scales were measured after performing the decomposition of the turbulent fields collected with various instrumentation techniques. Acoustic Doppler velocimetry and PIV had turbulence length scales equal to the flow depth, and the good agreement highlights the ability of the former to estimate length scales in streams. Large scale PIV provided length scales equal to 1.5 times the flow depth, but care should be used if directly inferring scales of macroturbulence from the free-surface. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.informaworld.com/smpp/content~db=all~content=a933311934~frm=titlelink [article] Comparison of macroturbulence measured using decomposition of PIV, ADV and LSPIV data [texte imprimé] / James F. Fox, Auteur ; Brian J. Belcher, Auteur . - 2011 . - pp. 122-126. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 49 N° 1 (Janvier/Fevrier 2011) . - pp. 122-126 Mots-clés : Gravel-bed  Open  channel  Scales  of  turbulence  Velocimetry 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 : Visualization and length-scale estimates are provided for turbulence in open channel flow over a gravel-bed. Results obtained using the digital particle image velocimetry (PIV) followed by post-processing with proper orthogonal decomposition showed higher and lower velocity regions aligned along a stagnation plane extending from the bed at approximately a 20° angle. Periodicity of second and fourth quadrant events equalled 0.20 s and agreed well with the outer variable defined bursting period. Normalized turbulence length scales were measured after performing the decomposition of the turbulent fields collected with various instrumentation techniques. Acoustic Doppler velocimetry and PIV had turbulence length scales equal to the flow depth, and the good agreement highlights the ability of the former to estimate length scales in streams. Large scale PIV provided length scales equal to 1.5 times the flow depth, but care should be used if directly inferring scales of macroturbulence from the free-surface. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.informaworld.com/smpp/content~db=all~content=a933311934~frm=titlelink

Outer scaling for open channel flow over a gravel bed / Brian J. Belcher in Journal of engineering mechanics, Vol. 137 N° 1 (Janvier 2011) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 137 N° 1 (Janvier 2011) . - pp.40-46 Titre : Outer scaling for open channel flow over a gravel bed Type de document : texte imprimé Auteurs : Brian J. Belcher, Auteur ; James F. Fox, Auteur Année de publication : 2011 Article en page(s) : pp.40-46 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Turbulence  Velocity  profile  Open  channel  flow  Gravel  River  beds. Résumé : Similarity analysis is performed for hydraulically rough open channel flow over a gravel bed to provide mixed outer scaling of the mean-velocity profile. The analysis is based on equilibrium turbulent boundary-layer theory derived using the asymptotic invariance principle. Outer scaling based on the similarity theory is validated with velocity measurements from the laboratory and field, having a Reynolds number range that includes 1×104, 1×105, and 1×106 and a Froude number range from 0.26 to 0.83. The results show that the free-stream velocity is an appropriate outer scale for gravel-bed river flows at moderate and bankfull stage. The results agree well with the velocity measurements and collapse laboratory and field data, which allow an important connection between open channel research in the laboratory and the applications for which the research is performed in the field. The results show that the R/aD84 roughness parameter is consistent with the mixed scale used in boundary-layer velocity scaling. This is in agreement with the consistent turbulent structure of the flow for both flat plate boundary-layer and open channel flow scenarios. While R/D84 has been used empirically with depth-averaged velocity and roughness laws for many years, this roughness parameter is shown in a theoretical context due to its influence on the turbulent structure of the flow. The results are applicable to modeling the velocity distribution under fundamental gravel-bed flow cases that span to the bankfull flow regime, which provides a contribution to stream engineering. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i1/p40_s1?isAuthorized=no [article] Outer scaling for open channel flow over a gravel bed [texte imprimé] / Brian J. Belcher, Auteur ; James F. Fox, Auteur . - 2011 . - pp.40-46. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 137 N° 1 (Janvier 2011) . - pp.40-46 Mots-clés : Turbulence  Velocity  profile  Open  channel  flow  Gravel  River  beds. Résumé : Similarity analysis is performed for hydraulically rough open channel flow over a gravel bed to provide mixed outer scaling of the mean-velocity profile. The analysis is based on equilibrium turbulent boundary-layer theory derived using the asymptotic invariance principle. Outer scaling based on the similarity theory is validated with velocity measurements from the laboratory and field, having a Reynolds number range that includes 1×104, 1×105, and 1×106 and a Froude number range from 0.26 to 0.83. The results show that the free-stream velocity is an appropriate outer scale for gravel-bed river flows at moderate and bankfull stage. The results agree well with the velocity measurements and collapse laboratory and field data, which allow an important connection between open channel research in the laboratory and the applications for which the research is performed in the field. The results show that the R/aD84 roughness parameter is consistent with the mixed scale used in boundary-layer velocity scaling. This is in agreement with the consistent turbulent structure of the flow for both flat plate boundary-layer and open channel flow scenarios. While R/D84 has been used empirically with depth-averaged velocity and roughness laws for many years, this roughness parameter is shown in a theoretical context due to its influence on the turbulent structure of the flow. The results are applicable to modeling the velocity distribution under fundamental gravel-bed flow cases that span to the bankfull flow regime, which provides a contribution to stream engineering. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i1/p40_s1?isAuthorized=no