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Characteristics of submerged jets in evolving scour hole downstream of an apron / Subhasish Dey in Journal of engineering mechanics, Vol. 134 n°11 (Novembre 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 n°11 (Novembre 2008) . - pp.927–936. Titre : Characteristics of submerged jets in evolving scour hole downstream of an apron Type de document : texte imprimé Auteurs : Subhasish Dey, Auteur ; Arindam Sarkar, Auteur Année de publication : 2008 Article en page(s) : pp.927–936. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Erosion  Open  channels  Turbulent  flow  Submerged  jets  Scour  Sediment  transport  Hydraulic Résumé : This paper reports an experimental investigation on the velocity and turbulence characteristics in an evolving scour hole downstream of an apron due to submerged jets issuing from a sluice opening detected by an acoustic Doppler velocimeter. Experiments were carried out for the conditions of submerged jets, having submergence factors from 0.96 to 1.85 and jet Froude numbers from 2.58 to 4.87, over sediment beds downstream of a rigid apron. The distributions of time-averaged velocity vectors, turbulence intensities, and Reynolds stress at different streamwise distances are plotted for the conditions of initial flat bed, intermediate scour holes, and equilibrium scour hole downstream of an apron. Vector plots of the flow field show that the rate of decay of the submerged jet velocity increases with an increase in scour hole dimension. The bed-shear stresses are determined from the Reynolds stress distributions. The flow characteristics in evolving scour holes are analyzed in the context of self-preservation, growth of the length scale, and decay of the velocity and turbulence characteristics scales. The most significant observation is that the flow in the scour holes (intermediate and equilibrium) is found to be plausibly self-preserving. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A11%289 [...] [article] Characteristics of submerged jets in evolving scour hole downstream of an apron [texte imprimé] / Subhasish Dey, Auteur ; Arindam Sarkar, Auteur . - 2008 . - pp.927–936. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°11 (Novembre 2008) . - pp.927–936. Mots-clés : Erosion  Open  channels  Turbulent  flow  Submerged  jets  Scour  Sediment  transport  Hydraulic Résumé : This paper reports an experimental investigation on the velocity and turbulence characteristics in an evolving scour hole downstream of an apron due to submerged jets issuing from a sluice opening detected by an acoustic Doppler velocimeter. Experiments were carried out for the conditions of submerged jets, having submergence factors from 0.96 to 1.85 and jet Froude numbers from 2.58 to 4.87, over sediment beds downstream of a rigid apron. The distributions of time-averaged velocity vectors, turbulence intensities, and Reynolds stress at different streamwise distances are plotted for the conditions of initial flat bed, intermediate scour holes, and equilibrium scour hole downstream of an apron. Vector plots of the flow field show that the rate of decay of the submerged jet velocity increases with an increase in scour hole dimension. The bed-shear stresses are determined from the Reynolds stress distributions. The flow characteristics in evolving scour holes are analyzed in the context of self-preservation, growth of the length scale, and decay of the velocity and turbulence characteristics scales. The most significant observation is that the flow in the scour holes (intermediate and equilibrium) is found to be plausibly self-preserving. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A11%289 [...]