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Kinematics of horseshoe vortex development in an evolving scour hole at a square cylinder / Rajkumar V. Raikar in Journal of hydraulic research, Vol. 46 N°2 (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 N°2 (2008) . - p. 247-264 Titre : Kinematics of horseshoe vortex development in an evolving scour hole at a square cylinder Titre original : Cinématique du developpement de vortex en fer à cheval dans un processus d'affouillement dû à une pile de section carrée Type de document : texte imprimé Auteurs : Rajkumar V. Raikar, Auteur ; Subhasish Dey, Auteur Article en page(s) : p. 247-264 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Bridge  pier  Hydraulics  Open  channel  flow  Sediment  transport  Steady  flow  Three-dimensional  flow  Turbulent  flow 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 : This paper presents an experimental investigation on the characteristics of the development of turbulent horseshoe vortex flow in an evolving (intermediate stages and equilibrium) scour hole at square cylinder measured by an acoustic Doppler velocimeter (ADV). As the primary objective was to study the turbulent flow characteristics of horseshoe vortex in an evolving scour hole, the flow zone downstream the cylinder was not considered. Experiments were conducted with a square cylinder of width 12 cm embedded in the bed of uniform sand of median diameter 0.81mm under the approaching flow having undisturbed flow depth (= 25 cm) greater than twice the width of the cylinder and the depth-averaged approaching flow velocity (= 35.7 cm/s) equaling approximately 0.95 times the critical velocity for the uniform bed sand. The ADV flow measurements were taken inside the intermediate scour holes (having depths of 0.25, 0.5 and 0.75 times the equilibrium scour depth) and the equilibrium scour hole (frozen by spraying glue). The contours of the time-averaged velocities, turbulence intensities and Reynolds stresses at different azimuthal planes (0º, 45º and 90º) are presented. The change of the characteristics of horseshoe vortex flow associated with a downflow from intermediate stages to equilibrium condition of scour hole is revealed through the vector plots of the flow field at different azimuthal planes. Also, the flow characteristics of the horseshoe vortex are analyzed from the point of view of similarity with the velocity and turbulence characteristic scales. The important observation is that the flow and the turbulence intensities in horseshoe vortex flow in a developing scour hole are reasonably similar. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Kinematics of horseshoe vortex development in an evolving scour hole at a square cylinder = Cinématique du developpement de vortex en fer à cheval dans un processus d'affouillement dû à une pile de section carrée [texte imprimé] / Rajkumar V. Raikar, Auteur ; Subhasish Dey, Auteur . - p. 247-264. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 N°2 (2008) . - p. 247-264 Mots-clés : Bridge  pier  Hydraulics  Open  channel  flow  Sediment  transport  Steady  flow  Three-dimensional  flow  Turbulent  flow 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 : This paper presents an experimental investigation on the characteristics of the development of turbulent horseshoe vortex flow in an evolving (intermediate stages and equilibrium) scour hole at square cylinder measured by an acoustic Doppler velocimeter (ADV). As the primary objective was to study the turbulent flow characteristics of horseshoe vortex in an evolving scour hole, the flow zone downstream the cylinder was not considered. Experiments were conducted with a square cylinder of width 12 cm embedded in the bed of uniform sand of median diameter 0.81mm under the approaching flow having undisturbed flow depth (= 25 cm) greater than twice the width of the cylinder and the depth-averaged approaching flow velocity (= 35.7 cm/s) equaling approximately 0.95 times the critical velocity for the uniform bed sand. The ADV flow measurements were taken inside the intermediate scour holes (having depths of 0.25, 0.5 and 0.75 times the equilibrium scour depth) and the equilibrium scour hole (frozen by spraying glue). The contours of the time-averaged velocities, turbulence intensities and Reynolds stresses at different azimuthal planes (0º, 45º and 90º) are presented. The change of the characteristics of horseshoe vortex flow associated with a downflow from intermediate stages to equilibrium condition of scour hole is revealed through the vector plots of the flow field at different azimuthal planes. Also, the flow characteristics of the horseshoe vortex are analyzed from the point of view of similarity with the velocity and turbulence characteristic scales. The important observation is that the flow and the turbulence intensities in horseshoe vortex flow in a developing scour hole are reasonably similar. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com