Comparison of far-field turbulent structure of a rectangular surface jet to three-dimensional free and wall jets / Soheil Gholamreza-Kashi in Journal of engineering mechanics, Vol. 134 N°3 (Mars 2008)  

Public ISBD [article]  inJournal of engineering mechanics > Vol. 134 N°3 (Mars 2008) . - pp.224–233. Titre : Comparison of far-field turbulent structure of a rectangular surface jet to three-dimensional free and wall jets Type de document : texte imprimé Auteurs : Soheil Gholamreza-Kashi, Auteur ; Robert J. Martinuzzi, Auteur ; Raouf E. Baddour, Auteur Année de publication : 2008 Article en page(s) : pp.224–233. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Surface jets Submerged Shear flow Three-dimensional Turbulent Résumé : The turbulence structure of a rectangular surface jet is compared to that of the three-dimensional free and wall jets. The surface jet turbulence quantities are mapped using laser Doppler velocimetry. In general, the turbulence structure of these three jets is found to be significantly different. For the surface jet, the free surface kinematic condition has a predominant effect on the whole structure, while for the wall jet, the influence of wall kinematic constraint is contained in the wall layer. A surface current with a higher lateral spreading rate than the submerged portion of the jet is developed, which does not exist for the wall jet because of the no-slip boundary condition. Unlike free jets, the submerged portion of the rectangular surface jet is characterized by two length scales. The Prandtl hypothesis with constant eddy viscosity provides a good estimate for the shear stresses in the lateral direction, but fails in the vertical direction, where the velocity profiles are much flatter, due to the free surface condition, than those for the free and wall jets. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A3%2822 [...] [article] Comparison of far-field turbulent structure of a rectangular surface jet to three-dimensional free and wall jets [texte imprimé] / Soheil Gholamreza-Kashi, Auteur ; Robert J. Martinuzzi, Auteur ; Raouf E. Baddour, Auteur . - 2008 . - pp.224–233. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°3 (Mars 2008) . - pp.224–233. Mots-clés : Surface jets Submerged Shear flow Three-dimensional Turbulent Résumé : The turbulence structure of a rectangular surface jet is compared to that of the three-dimensional free and wall jets. The surface jet turbulence quantities are mapped using laser Doppler velocimetry. In general, the turbulence structure of these three jets is found to be significantly different. For the surface jet, the free surface kinematic condition has a predominant effect on the whole structure, while for the wall jet, the influence of wall kinematic constraint is contained in the wall layer. A surface current with a higher lateral spreading rate than the submerged portion of the jet is developed, which does not exist for the wall jet because of the no-slip boundary condition. Unlike free jets, the submerged portion of the rectangular surface jet is characterized by two length scales. The Prandtl hypothesis with constant eddy viscosity provides a good estimate for the shear stresses in the lateral direction, but fails in the vertical direction, where the velocity profiles are much flatter, due to the free surface condition, than those for the free and wall jets. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A3%2822 [...]

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Free-surface stretching-sustained intake vortices / Rupp Carriveau in Journal of hydraulic research, Vol. 47 N° 4 (2009)  

Public ISBD [article]  inJournal of hydraulic research > Vol. 47 N° 4 (2009) . - pp. 486-491 Titre : Free-surface stretching-sustained intake vortices Titre original : Vortex de prise soutenus par étirement en surface Type de document : texte imprimé Auteurs : Rupp Carriveau, Auteur ; Gregory A. Koop, Auteur ; Raouf E. Baddour, Auteur Article en page(s) : pp. 486-491 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Dye-core vortex Free-surface intake Intake submergence model formation Stretching-sustained Vortex stret ching 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 : An experimental investigation of vortices at deep hydraulic intakes revealed two distinct categories of free surface intake vortex. In case 1 when the strain field was strong enough, without an external, quantifiable source of vorticity, minor asymmetries in the near radial intake flow were concentrated and amplified into a vortex core that was purely stretching sustained (PSS). This vortex did not decay so long as the rate of intake withdrawal did not decrease. In case 2, vortex formation required that there be an ample and regular supply of external vorticity to interact with weaker strain fields. These non-purely stretching-sustained (NPSS) vortices decay with a decrease in externally supplied vorticity while maintaining the rate of intake withdrawal. A parameter, here named the stretching-sustained submergence, was postulated to classify conditions suitable for purely stretching sustained vortex formation. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Free-surface stretching-sustained intake vortices = Vortex de prise soutenus par étirement en surface [texte imprimé] / Rupp Carriveau, Auteur ; Gregory A. Koop, Auteur ; Raouf E. Baddour, Auteur . - pp. 486-491. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 47 N° 4 (2009) . - pp. 486-491 Mots-clés : Dye-core vortex Free-surface intake Intake submergence model formation Stretching-sustained Vortex stret ching 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 : An experimental investigation of vortices at deep hydraulic intakes revealed two distinct categories of free surface intake vortex. In case 1 when the strain field was strong enough, without an external, quantifiable source of vorticity, minor asymmetries in the near radial intake flow were concentrated and amplified into a vortex core that was purely stretching sustained (PSS). This vortex did not decay so long as the rate of intake withdrawal did not decrease. In case 2, vortex formation required that there be an ample and regular supply of external vorticity to interact with weaker strain fields. These non-purely stretching-sustained (NPSS) vortices decay with a decrease in externally supplied vorticity while maintaining the rate of intake withdrawal. A parameter, here named the stretching-sustained submergence, was postulated to classify conditions suitable for purely stretching sustained vortex formation. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

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