Documents disponibles écrits par cet auteur

Effect of selected parameters on the depositional behaviour of turbidity currents / Ehsan Khavasi in Journal of hydraulic research, Vol. 50 N° 1 (Janvier/Février 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 1 (Janvier/Février 2012) . - pp. 60-69 Titre : Effect of selected parameters on the depositional behaviour of turbidity currents Type de document : texte imprimé Auteurs : Ehsan Khavasi, Auteur ; Hossein Afshin, Auteur ; Bahar Firoozabadi, Auteur Année de publication : 2012 Article en page(s) : pp. 60-69 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Deposition  Inlet  Froude  number  Suspended  sediment  flux  Turbidity  current Résumé : Turbidity currents containing kaolin particles were studied experimentally in a channel and the velocity and concentration profiles were measured using an acoustic Doppler velocimeter. These experiments were performed to investigate the depositional behaviour of turbidity currents. The suspended sediment flux was evaluated by experimental and analytical methods and the results of these two methods were in a good agreement. To evaluate the suspended sediment flux, it was necessary to recognize the suspended sediment zone from the upper shear layer region and near the bed depositional area as well. The method of determination of these areas is discussed. The effects of important parameters including the inlet Froude number and bed slope were also studied. Based on these results, it can be concluded that the non-dimensional sediment flux decreases at the vicinity of the hydraulic jump with the inlet Froude number, whereas an increase in the bed slope reduces the non-dimensional sediment flux. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.641763 [article] Effect of selected parameters on the depositional behaviour of turbidity currents [texte imprimé] / Ehsan Khavasi, Auteur ; Hossein Afshin, Auteur ; Bahar Firoozabadi, Auteur . - 2012 . - pp. 60-69. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 1 (Janvier/Février 2012) . - pp. 60-69 Mots-clés : Deposition  Inlet  Froude  number  Suspended  sediment  flux  Turbidity  current Résumé : Turbidity currents containing kaolin particles were studied experimentally in a channel and the velocity and concentration profiles were measured using an acoustic Doppler velocimeter. These experiments were performed to investigate the depositional behaviour of turbidity currents. The suspended sediment flux was evaluated by experimental and analytical methods and the results of these two methods were in a good agreement. To evaluate the suspended sediment flux, it was necessary to recognize the suspended sediment zone from the upper shear layer region and near the bed depositional area as well. The method of determination of these areas is discussed. The effects of important parameters including the inlet Froude number and bed slope were also studied. Based on these results, it can be concluded that the non-dimensional sediment flux decreases at the vicinity of the hydraulic jump with the inlet Froude number, whereas an increase in the bed slope reduces the non-dimensional sediment flux. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.641763

Experimental observation of the flow structure of turbidity currents / Zahra Nourmohammadi in Journal of hydraulic research, Vol. 49 N° 2 (Mars/Avril 2011) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 168-177 Titre : Experimental observation of the flow structure of turbidity currents Type de document : texte imprimé Auteurs : Zahra Nourmohammadi, Auteur ; Hossein Afshin, Auteur ; Bahar Firoozabadi, Auteur Année de publication : 2011 Article en page(s) : pp. 168-177 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Froude  number  Hydraulic  jump  Sediment-laden  density  current  Turbidity  current  Velocity  profile 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 structure of turbidity currents released on a sloping bed below fresh water is investigated. Kaolin is used as a suspended material. Laboratory observations indicate that if a dense layer moves through the channel, the current thickness increases due to a hydraulic jump. This phenomenon occurs under special inlet conditions and has a significant effect on the current structure including velocity profile, current height and bed shear stress. Flows with different inlet Froude numbers based on various inlet concentrations behave more distinctly than those based on different inlet opening heights. Laboratory experiments indicate that an increase in the inlet Froude number causes an increase in the height of sediment-laden density currents and a decrease in the maximum cross-sectional velocity. The effects of the hydraulic jump on the bed shear stress are also investigated. A decrease in this stress and the average velocity is remarkable after the current has passed the jump. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.543777 [article] Experimental observation of the flow structure of turbidity currents [texte imprimé] / Zahra Nourmohammadi, Auteur ; Hossein Afshin, Auteur ; Bahar Firoozabadi, Auteur . - 2011 . - pp. 168-177. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 168-177 Mots-clés : Froude  number  Hydraulic  jump  Sediment-laden  density  current  Turbidity  current  Velocity  profile 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 structure of turbidity currents released on a sloping bed below fresh water is investigated. Kaolin is used as a suspended material. Laboratory observations indicate that if a dense layer moves through the channel, the current thickness increases due to a hydraulic jump. This phenomenon occurs under special inlet conditions and has a significant effect on the current structure including velocity profile, current height and bed shear stress. Flows with different inlet Froude numbers based on various inlet concentrations behave more distinctly than those based on different inlet opening heights. Laboratory experiments indicate that an increase in the inlet Froude number causes an increase in the height of sediment-laden density currents and a decrease in the maximum cross-sectional velocity. The effects of the hydraulic jump on the bed shear stress are also investigated. A decrease in this stress and the average velocity is remarkable after the current has passed the jump. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.543777