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Near-bed particle motion over transitionally-rough bed / Bhaskar Ramesh in Journal of hydraulic research, Vol. 49 N° 6 (Novembre/Décembre 2011) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 49 N° 6 (Novembre/Décembre 2011) . - pp. 757-765 Titre : Near-bed particle motion over transitionally-rough bed Type de document : texte imprimé Auteurs : Bhaskar Ramesh, Auteur ; Umesh C. Kothyari, Auteur ; Krishnan Murugesan, Auteur Année de publication : 2012 Article en page(s) : pp. 757-765 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Particle  motion  Rolling  Saltation  Sediment  motion  Shear  stress  Transitionally-rough  bed 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 : The motion of sediment particles over a transitionally-rough bed is studied experimentally using a real-time high-speed imaging system. Vertical distributions of the instantaneous flow velocities were measured using acoustic Doppler velocimetry. The sediment saltation trajectories and the associated velocity components were deciphered from the high-speed images using digital image processing techniques. Sediments of different sizes and specific weights were used for experimentation. Particles moving in both the rolling and the saltation regimes were tested. Stochastic deviations of the particle velocity, the particle acceleration and the angle of velocity vector orientation during its motion due to particle interactions with flow and the channel bed are quantified. The angle distributions and the acceleration fluctuations are approximately bell-shaped. Using the experimental data, a generalized single relation for particle velocity is proposed for saltation and rolling sediments. The results of particle motion on movable-rough and fixed-rough beds available in the literature are also included for comparison. The data presented herein are useful for stochastic modelling of bed-load transport. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.620369 [article] Near-bed particle motion over transitionally-rough bed [texte imprimé] / Bhaskar Ramesh, Auteur ; Umesh C. Kothyari, Auteur ; Krishnan Murugesan, Auteur . - 2012 . - pp. 757-765. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 49 N° 6 (Novembre/Décembre 2011) . - pp. 757-765 Mots-clés : Particle  motion  Rolling  Saltation  Sediment  motion  Shear  stress  Transitionally-rough  bed 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 : The motion of sediment particles over a transitionally-rough bed is studied experimentally using a real-time high-speed imaging system. Vertical distributions of the instantaneous flow velocities were measured using acoustic Doppler velocimetry. The sediment saltation trajectories and the associated velocity components were deciphered from the high-speed images using digital image processing techniques. Sediments of different sizes and specific weights were used for experimentation. Particles moving in both the rolling and the saltation regimes were tested. Stochastic deviations of the particle velocity, the particle acceleration and the angle of velocity vector orientation during its motion due to particle interactions with flow and the channel bed are quantified. The angle distributions and the acceleration fluctuations are approximately bell-shaped. Using the experimental data, a generalized single relation for particle velocity is proposed for saltation and rolling sediments. The results of particle motion on movable-rough and fixed-rough beds available in the literature are also included for comparison. The data presented herein are useful for stochastic modelling of bed-load transport. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.620369