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Ajouter le résultat dans votre panierBreaching of overtopped river embankments controlled by apparent cohesion / Gerd Pickert in Journal of hydraulic research, Vol. 49 N° 2 (Mars/Avril 2011)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 143-156
Titre : Breaching of overtopped river embankments controlled by apparent cohesion Type de document : texte imprimé Auteurs : Gerd Pickert, Auteur ; Volker Weitbrecht, Auteur ; Andreas Bieberstein, Auteur Année de publication : 2011 Article en page(s) : pp. 143-156 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Breach formation Dam failure Embankment failure Fringe projection method Laboratory experiment Pore-water pressure 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 : Laboratory experiments were conducted to obtain detailed experimental data of high temporal and spatial resolution on the breach of homogeneous non-cohesive embankments due to overtopping. These results supplement earlier data for this embankment type by providing information on the breach discharge, longitudinal and transversal breach profiles, erosion rates and pore-water pressures within the embankment. Based on detailed experimental results, two breach phases are classified. Shear and tension failure mechanisms were identified from the analysis of the obtained cross-sectional breach profiles. Furthermore, the temporal cross-sectional analysis of the used non-cohesive granular material shows a different behaviour regarding the lateral breach widening and the breach slope failure. The data analysis indicates that the apparent cohesion represented by the pore-water pressure influences the stability of the breach side slopes and hence the complete breach process. This finding is confirmed by a dimensional analysis of the experimental data and compared with information from earlier work.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552468 [article] Breaching of overtopped river embankments controlled by apparent cohesion [texte imprimé] / Gerd Pickert, Auteur ; Volker Weitbrecht, Auteur ; Andreas Bieberstein, Auteur . - 2011 . - pp. 143-156.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 143-156
Mots-clés : Breach formation Dam failure Embankment failure Fringe projection method Laboratory experiment Pore-water pressure 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 : Laboratory experiments were conducted to obtain detailed experimental data of high temporal and spatial resolution on the breach of homogeneous non-cohesive embankments due to overtopping. These results supplement earlier data for this embankment type by providing information on the breach discharge, longitudinal and transversal breach profiles, erosion rates and pore-water pressures within the embankment. Based on detailed experimental results, two breach phases are classified. Shear and tension failure mechanisms were identified from the analysis of the obtained cross-sectional breach profiles. Furthermore, the temporal cross-sectional analysis of the used non-cohesive granular material shows a different behaviour regarding the lateral breach widening and the breach slope failure. The data analysis indicates that the apparent cohesion represented by the pore-water pressure influences the stability of the breach side slopes and hence the complete breach process. This finding is confirmed by a dimensional analysis of the experimental data and compared with information from earlier work.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552468
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 157-167
Titre : Effect of a vegetation patch on turbulent channel flow Type de document : texte imprimé Auteurs : Dimitris Souliotis, Auteur ; Panayotis Prinos, Auteur Année de publication : 2011 Article en page(s) : pp. 157-167 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bed shear stress Flow characteristics Open channel Turbulence model Vegetation patch 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 effect of a vegetation patch (VP) on the flow and turbulence characteristics is studied. Two turbulence models are used to simulate patch presence. Numerical results for both mean and turbulence flow characteristics are compared with available measurements to assess the performance of these models for dense and sparse submerged VPs. The mechanisms which control the turbulent development inside the VP are also discussed, and the patch effect on the downstream flow and turbulence is assessed. The results indicate that the patch length and the vegetation density dominate the turbulent development. An increase in the vegetation density causes acceleration of the development of flow velocity and turbulence characteristics inside the patch and increases the channel length downstream of the patch where its effect is significant. Also areas with increased and decreased values of bed shear stresses are observed at the initial part and at the end of the patch, respectively.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.557258 [article] Effect of a vegetation patch on turbulent channel flow [texte imprimé] / Dimitris Souliotis, Auteur ; Panayotis Prinos, Auteur . - 2011 . - pp. 157-167.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 157-167
Mots-clés : Bed shear stress Flow characteristics Open channel Turbulence model Vegetation patch 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 effect of a vegetation patch (VP) on the flow and turbulence characteristics is studied. Two turbulence models are used to simulate patch presence. Numerical results for both mean and turbulence flow characteristics are compared with available measurements to assess the performance of these models for dense and sparse submerged VPs. The mechanisms which control the turbulent development inside the VP are also discussed, and the patch effect on the downstream flow and turbulence is assessed. The results indicate that the patch length and the vegetation density dominate the turbulent development. An increase in the vegetation density causes acceleration of the development of flow velocity and turbulence characteristics inside the patch and increases the channel length downstream of the patch where its effect is significant. Also areas with increased and decreased values of bed shear stresses are observed at the initial part and at the end of the patch, respectively.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.557258
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
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 178-193
Titre : Downstream fining processes in sandy lowland rivers Type de document : texte imprimé Auteurs : Roy M. Frings, Auteur ; Willem Ottevanger, Auteur ; Kees (C.J.) Sloff, Auteur Année de publication : 2011 Article en page(s) : pp. 178-193 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Downstream fining Dune sorting Longitudinal bed profile Meander migration Overbank deposition River bifurcation Sand-bed river Selective transport Rhine River 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 : Downstream fining of river bed sediments is well known for gravel-bed rivers, but also occurs in sand-bed rivers. The objective of this study was to determine the effect of selective transport processes, dune sorting, overbank deposition, channel migration and river bifurcations on downstream fining in sandy lowland rivers subject to relative sea level rise, tidal water level variations and increasing river width. A numerical simulation model was built using the Delft3D software. Selective suspended-load transport appeared to be dominant over selective bed-load transport. Dune sorting and channel migration increase fining rates, but overbank deposition has an opposite effect. River bifurcations affect the fining rate because of their effect on the sediment supply to bifurcating lowland rivers. Downstream fining was found to develop within decades, but it took few centuries before the longitudinal bed profile and the fining rate attained dynamic equilibrium. A comparison of the modelled fining rates with those observed in the Rhine River shows reasonable agreement.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.561000 [article] Downstream fining processes in sandy lowland rivers [texte imprimé] / Roy M. Frings, Auteur ; Willem Ottevanger, Auteur ; Kees (C.J.) Sloff, Auteur . - 2011 . - pp. 178-193.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 178-193
Mots-clés : Downstream fining Dune sorting Longitudinal bed profile Meander migration Overbank deposition River bifurcation Sand-bed river Selective transport Rhine River 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 : Downstream fining of river bed sediments is well known for gravel-bed rivers, but also occurs in sand-bed rivers. The objective of this study was to determine the effect of selective transport processes, dune sorting, overbank deposition, channel migration and river bifurcations on downstream fining in sandy lowland rivers subject to relative sea level rise, tidal water level variations and increasing river width. A numerical simulation model was built using the Delft3D software. Selective suspended-load transport appeared to be dominant over selective bed-load transport. Dune sorting and channel migration increase fining rates, but overbank deposition has an opposite effect. River bifurcations affect the fining rate because of their effect on the sediment supply to bifurcating lowland rivers. Downstream fining was found to develop within decades, but it took few centuries before the longitudinal bed profile and the fining rate attained dynamic equilibrium. A comparison of the modelled fining rates with those observed in the Rhine River shows reasonable agreement.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.561000
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 194-204
Titre : Particle bed deformation in front of a weir induced by subcritical laminar flow Type de document : texte imprimé Auteurs : Sebastien Muller, Auteur ; Pascal Guiraud, Auteur ; Alain Line, Auteur Année de publication : 2011 Article en page(s) : pp. 194-204 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bed-load Gravity settler Open channel flow Particle bed deformation Particle entrainment Weir 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 behaviour of a particle bed subjected to viscous flow upstream of a weir is experimentally examined. Experiments were conducted in a rectangular flume in which oil circulated above a bed of solid particles. Within about 150 mm upstream of the weir, the bed underwent a significant change and took the shape of a dune. The temporal evolutions of dune position and dune size were determined for various discharges and weir heights. At the steady state, both parameters were independent of discharge but affected by the weir height. Results indicate that the position of the axial dune crest varies linearly with the weir height. The two mechanisms controlling the formation and evolution of the dune are the particle bed loading by the approach flow and the particle entrainment inside the separation boundary layer.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552460 [article] Particle bed deformation in front of a weir induced by subcritical laminar flow [texte imprimé] / Sebastien Muller, Auteur ; Pascal Guiraud, Auteur ; Alain Line, Auteur . - 2011 . - pp. 194-204.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 194-204
Mots-clés : Bed-load Gravity settler Open channel flow Particle bed deformation Particle entrainment Weir 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 behaviour of a particle bed subjected to viscous flow upstream of a weir is experimentally examined. Experiments were conducted in a rectangular flume in which oil circulated above a bed of solid particles. Within about 150 mm upstream of the weir, the bed underwent a significant change and took the shape of a dune. The temporal evolutions of dune position and dune size were determined for various discharges and weir heights. At the steady state, both parameters were independent of discharge but affected by the weir height. Results indicate that the position of the axial dune crest varies linearly with the weir height. The two mechanisms controlling the formation and evolution of the dune are the particle bed loading by the approach flow and the particle entrainment inside the separation boundary layer.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552460
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 205-212
Titre : Numerical model for flood routing with a Cartesian cut-cell domain Type de document : texte imprimé Auteurs : Hyung-Jun Kim, Auteur ; Yong-Sik Cho, Auteur Année de publication : 2011 Article en page(s) : pp. 205-212 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Cut-cell system Dam-break Finite volume method Shallow-water Shock-capturing 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 : Flood risk analysis requires adequate numerical modeling to estimate the inundation depth and velocity in a wide-ranging study area. Thus, accurate, simple, and efficient numerical models with adequate mesh systems are needed for large-scale flood simulations. A numerical model based on a finite volume approach with the Cartesian cut-cell method is adopted herein to solve the shallow-water equations. To improve the representation of the flow domain, a modified cut-cell technique is suggested. The modified cut-cell mesh can be generated by a mesh merging process which needs two or more cut-cell meshes for different flow characteristic domains such as a compound meandering channel with steps. The modified cut-cell mesh indicated a reasonable flow domain to represent complicated domains. To verify the accuracy and stability of the present numerical model, various tests were performed and the obtained predictions compared with available exact solutions and laboratory measurements. A very reasonable agreement was observed.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.547037 [article] Numerical model for flood routing with a Cartesian cut-cell domain [texte imprimé] / Hyung-Jun Kim, Auteur ; Yong-Sik Cho, Auteur . - 2011 . - pp. 205-212.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 205-212
Mots-clés : Cut-cell system Dam-break Finite volume method Shallow-water Shock-capturing 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 : Flood risk analysis requires adequate numerical modeling to estimate the inundation depth and velocity in a wide-ranging study area. Thus, accurate, simple, and efficient numerical models with adequate mesh systems are needed for large-scale flood simulations. A numerical model based on a finite volume approach with the Cartesian cut-cell method is adopted herein to solve the shallow-water equations. To improve the representation of the flow domain, a modified cut-cell technique is suggested. The modified cut-cell mesh can be generated by a mesh merging process which needs two or more cut-cell meshes for different flow characteristic domains such as a compound meandering channel with steps. The modified cut-cell mesh indicated a reasonable flow domain to represent complicated domains. To verify the accuracy and stability of the present numerical model, various tests were performed and the obtained predictions compared with available exact solutions and laboratory measurements. A very reasonable agreement was observed.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.547037
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 213-221
Titre : Leak detection in complex series pipelines by using the system frequency response method Type de document : texte imprimé Auteurs : Huan-Feng Duan, Auteur ; Lee, Pedro J., Auteur ; Mohamed S. Ghidaouic, Auteur Année de publication : 2011 Article en page(s) : pp. 213-221 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Complex series pipeline Frequency-response function Junction reflection Leak detection Transient 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 research investigates the applicability of the transient-based frequency-response function (FRF) method for detecting leaks in complex series pipelines. The behaviour of transient waves in these pipelines with internal series junctions indicates that junction reflections modify the system resonant frequencies but have a small effect on the leak-induced information contained within the system frequency responses. The analogous method previously developed for single pipelines is extended to complex series pipe systems by using the analytical transfer matrix method herein and the extended method is validated by two simple numerical experimental cases consisting of 3-series pipes and 10-series pipes, respectively. The applied results indicate that the extended FRF method can be applied to detect single and multiple leaks in complex series pipelines as long as the location and size of the resonant peaks of system frequency responses are accurately determined.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.553486 [article] Leak detection in complex series pipelines by using the system frequency response method [texte imprimé] / Huan-Feng Duan, Auteur ; Lee, Pedro J., Auteur ; Mohamed S. Ghidaouic, Auteur . - 2011 . - pp. 213-221.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 213-221
Mots-clés : Complex series pipeline Frequency-response function Junction reflection Leak detection Transient 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 research investigates the applicability of the transient-based frequency-response function (FRF) method for detecting leaks in complex series pipelines. The behaviour of transient waves in these pipelines with internal series junctions indicates that junction reflections modify the system resonant frequencies but have a small effect on the leak-induced information contained within the system frequency responses. The analogous method previously developed for single pipelines is extended to complex series pipe systems by using the analytical transfer matrix method herein and the extended method is validated by two simple numerical experimental cases consisting of 3-series pipes and 10-series pipes, respectively. The applied results indicate that the extended FRF method can be applied to detect single and multiple leaks in complex series pipelines as long as the location and size of the resonant peaks of system frequency responses are accurately determined.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.553486
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 222-230
Titre : Spatial evolution of turbulence characteristics in weak hydraulic jumps Type de document : texte imprimé Auteurs : Emmanuel Mignot, Auteur ; Cienfuegos, Rodrigo, Auteur Année de publication : 2011 Article en page(s) : pp. 222-230 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Approach flow Experimentation Hydraulic jump Inflow development Turbulent kinetic energy 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 experimental investigation focuses on the turbulence features of weak hydraulic jumps in rectangular channels for two different approach flow lengths. The turbulent kinetic energy equation includes the turbulence production and dissipation terms, two advection and two turbulent transport terms and the pressure transport term, which could not be measured, however. For jumps with a limited approach flow length, the turbulence production is mostly confined to the shear layer, while for jumps with a longer approach flow length, an additional peak turbulence production region is observed at the near-wall region due to boundary layer separation. The turbulent energy is then transported by the mean flow both towards the free surface and into the downstream direction and is diffused by turbulent processes away from the energetic shear layer towards less energetic regions. Dissipation occurs mostly in the shear layer along the upstream portion of the jump and over most of the flow depth further downstream.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.554208 [article] Spatial evolution of turbulence characteristics in weak hydraulic jumps [texte imprimé] / Emmanuel Mignot, Auteur ; Cienfuegos, Rodrigo, Auteur . - 2011 . - pp. 222-230.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 222-230
Mots-clés : Approach flow Experimentation Hydraulic jump Inflow development Turbulent kinetic energy 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 experimental investigation focuses on the turbulence features of weak hydraulic jumps in rectangular channels for two different approach flow lengths. The turbulent kinetic energy equation includes the turbulence production and dissipation terms, two advection and two turbulent transport terms and the pressure transport term, which could not be measured, however. For jumps with a limited approach flow length, the turbulence production is mostly confined to the shear layer, while for jumps with a longer approach flow length, an additional peak turbulence production region is observed at the near-wall region due to boundary layer separation. The turbulent energy is then transported by the mean flow both towards the free surface and into the downstream direction and is diffused by turbulent processes away from the energetic shear layer towards less energetic regions. Dissipation occurs mostly in the shear layer along the upstream portion of the jump and over most of the flow depth further downstream.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.554208
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 231-238
Titre : Division of critical flow at three-branch open-channel intersection Type de document : texte imprimé Auteurs : Kamal El Kadi Abderrezzak, Auteur ; Leszek Lewicki, Auteur ; André Paquier, Auteur Année de publication : 2011 Article en page(s) : pp. 231-238 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Channel intersection Depth-averaged model Dividing flow Laboratory experiment Open channel junction Transcritical 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 : An experimental study of the characteristics of dividing critical flows in a 90° open-channel junction formed by three horizontal equal-width branches is presented, conducted for various inflow discharges and downstream boundary conditions. Outflow discharges and flow depths were also measured. Four main flow patterns are identified considering the location and length of the hydraulic jumps that develop across the main and lateral channels. A relationship between the discharge division ratio and the tailwater Froude number is found, reproducing well the experimental data. Practical applications of this relationship include the design of open channel and pipe networks and one-dimensional numerical modelling of flood propagation in urban areas. The study shows also that a two-dimensional depth-averaged numerical model hardly gives better predictions of the discharge ratios because of the presence of three-dimensional features at the junction.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.558174 [article] Division of critical flow at three-branch open-channel intersection [texte imprimé] / Kamal El Kadi Abderrezzak, Auteur ; Leszek Lewicki, Auteur ; André Paquier, Auteur . - 2011 . - pp. 231-238.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 231-238
Mots-clés : Channel intersection Depth-averaged model Dividing flow Laboratory experiment Open channel junction Transcritical 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 : An experimental study of the characteristics of dividing critical flows in a 90° open-channel junction formed by three horizontal equal-width branches is presented, conducted for various inflow discharges and downstream boundary conditions. Outflow discharges and flow depths were also measured. Four main flow patterns are identified considering the location and length of the hydraulic jumps that develop across the main and lateral channels. A relationship between the discharge division ratio and the tailwater Froude number is found, reproducing well the experimental data. Practical applications of this relationship include the design of open channel and pipe networks and one-dimensional numerical modelling of flood propagation in urban areas. The study shows also that a two-dimensional depth-averaged numerical model hardly gives better predictions of the discharge ratios because of the presence of three-dimensional features at the junction.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.558174
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 239-247
Titre : Friction factor and von Kármán's k in open channels with bed-load Type de document : texte imprimé Auteurs : Roberto Gaudio, Auteur ; Antonio Miglio, Auteur ; Francesco Calomino, Auteur Année de publication : 2011 Article en page(s) : pp. 239-247 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bed-load Friction factor Narrow flume Open channel Von Kàrmàn's k 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 assessment of the friction factor in open-channel flows with sediments is still an unsolved problem. For bed-load, various studies led to contrasting results, some finding that the friction factor is not affected by the sediment transport, whereas others observed an increase with the sediment concentration. Its effect was analysed in few studies only with gravel bed-load, and an empirical formula was proposed to predict the bed friction factor for pipe and open-channel flows, yet with a limited physical meaning and a general deviation of open-channel data. Also the von Kármán's κ has been recognized to vary with sediment transport. In the framework of classical dimensional analysis, laboratory investigations are here extended to sand bed-load and new empirical formulae based on both original and literature data are proposed for the assessment of the bed friction factor and von Kármán's κ, thereby accounting for the main parameters which affect resistance.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.561001 [article] Friction factor and von Kármán's k in open channels with bed-load [texte imprimé] / Roberto Gaudio, Auteur ; Antonio Miglio, Auteur ; Francesco Calomino, Auteur . - 2011 . - pp. 239-247.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 239-247
Mots-clés : Bed-load Friction factor Narrow flume Open channel Von Kàrmàn's k 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 assessment of the friction factor in open-channel flows with sediments is still an unsolved problem. For bed-load, various studies led to contrasting results, some finding that the friction factor is not affected by the sediment transport, whereas others observed an increase with the sediment concentration. Its effect was analysed in few studies only with gravel bed-load, and an empirical formula was proposed to predict the bed friction factor for pipe and open-channel flows, yet with a limited physical meaning and a general deviation of open-channel data. Also the von Kármán's κ has been recognized to vary with sediment transport. In the framework of classical dimensional analysis, laboratory investigations are here extended to sand bed-load and new empirical formulae based on both original and literature data are proposed for the assessment of the bed friction factor and von Kármán's κ, thereby accounting for the main parameters which affect resistance.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.561001
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 248-256
Titre : Drag force and associated backwater effect due to an open channel spur dike field Type de document : texte imprimé Auteurs : Hossein Azinfar, Auteur ; James A. Kells, Auteur Année de publication : 2011 Article en page(s) : pp. 248-256 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Backwater effect Drag force flow resistance River engineering Spur dike field 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 study focuses on quantifying the flow resistance and the associated backwater effect of a spur dike field in an open channel flow. The work was carried out in a rigid bed flume. The model spur dikes were simulated using two-dimensional (2D), rectangular plates placed in an array along one side of the flume. The results indicate that the arrangement of a spur dike field has a substantial effect on the drag force and hence the backwater effect that is experienced. In general, the total drag force of a spur dike field increases as the number of spur dikes and the relative spacing between them increase. The most upstream spur dike experienced the greatest drag force among the entire spur field, essentially acting as a shield, resulting in a reduction in the drag force of the downstream spur dikes.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552470 [article] Drag force and associated backwater effect due to an open channel spur dike field [texte imprimé] / Hossein Azinfar, Auteur ; James A. Kells, Auteur . - 2011 . - pp. 248-256.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 248-256
Mots-clés : Backwater effect Drag force flow resistance River engineering Spur dike field 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 study focuses on quantifying the flow resistance and the associated backwater effect of a spur dike field in an open channel flow. The work was carried out in a rigid bed flume. The model spur dikes were simulated using two-dimensional (2D), rectangular plates placed in an array along one side of the flume. The results indicate that the arrangement of a spur dike field has a substantial effect on the drag force and hence the backwater effect that is experienced. In general, the total drag force of a spur dike field increases as the number of spur dikes and the relative spacing between them increase. The most upstream spur dike experienced the greatest drag force among the entire spur field, essentially acting as a shield, resulting in a reduction in the drag force of the downstream spur dikes.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552470
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 257-262
Titre : Flow resistance over fixed roughness elements Type de document : texte imprimé Auteurs : Yang, Shu-Qing, Auteur ; Yu Han, Auteur ; Nadeesha Dharmasiri, Auteur Année de publication : 2011 Article en page(s) : pp. 257-262 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Friction factor Open channel flow Pipe flow Reynolds number 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 : The underlying mechanism of flow resistance in open channels and pipelines over rough boundary is investigated. Different from Einstein's method, this work extends the principle of boundary shear stress summation in a mobile bed to the rigid boundary. It is found that the principle is valid to express the friction factor in all pipe flow regimes, mainly concerning the transition from laminar to turbulent flows, and between fully smooth and fully rough turbulent flows. This research also evaluates the concept developed by Einstein regarding the relationship between skin friction and form drag. Experimental data of Nikuradse are used to test the obtained results, indicating that the above-mentioned method yields the best agreement with experimental data, relative to the other friction factor formulas available in the literature.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.540121 [article] Flow resistance over fixed roughness elements [texte imprimé] / Yang, Shu-Qing, Auteur ; Yu Han, Auteur ; Nadeesha Dharmasiri, Auteur . - 2011 . - pp. 257-262.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 257-262
Mots-clés : Friction factor Open channel flow Pipe flow Reynolds number 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 : The underlying mechanism of flow resistance in open channels and pipelines over rough boundary is investigated. Different from Einstein's method, this work extends the principle of boundary shear stress summation in a mobile bed to the rigid boundary. It is found that the principle is valid to express the friction factor in all pipe flow regimes, mainly concerning the transition from laminar to turbulent flows, and between fully smooth and fully rough turbulent flows. This research also evaluates the concept developed by Einstein regarding the relationship between skin friction and form drag. Experimental data of Nikuradse are used to test the obtained results, indicating that the above-mentioned method yields the best agreement with experimental data, relative to the other friction factor formulas available in the literature.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.540121
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 263-266
Titre : Frequency responses of single and multiple partial pipeline blockages Type de document : texte imprimé Auteurs : Pranab K. Mohapatra, Auteur ; M. Hanif Chaudhry, Auteur Année de publication : 2011 Article en page(s) : pp. 263-266 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Frequency domain Periodic flow Pipe blockage Pipe flow Piping system 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 discrete Fourier transform (FT) of the peak pressure frequency response (PPFR) at a downstream valve generated by the transfer matrix method is used to detect a partial pipeline blockage. The location of this blockage is detected by locating the peak in the FT of the PPFR. This is also valid if multiple partial blockages are present. A methodology to detect individual blockage sizes is presented for single and double partial blockages. Yet, the present methodology is unsuccessful to predict the individual sizes if there are more than two partial blockages. However, the combined size of the partial blockages is detected by the magnitude of the zeroth frequency. In addition, special cases of partial blockage are presented to indicate the limitations of the present methodology.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.544887 [article] Frequency responses of single and multiple partial pipeline blockages [texte imprimé] / Pranab K. Mohapatra, Auteur ; M. Hanif Chaudhry, Auteur . - 2011 . - pp. 263-266.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 263-266
Mots-clés : Frequency domain Periodic flow Pipe blockage Pipe flow Piping system 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 discrete Fourier transform (FT) of the peak pressure frequency response (PPFR) at a downstream valve generated by the transfer matrix method is used to detect a partial pipeline blockage. The location of this blockage is detected by locating the peak in the FT of the PPFR. This is also valid if multiple partial blockages are present. A methodology to detect individual blockage sizes is presented for single and double partial blockages. Yet, the present methodology is unsuccessful to predict the individual sizes if there are more than two partial blockages. However, the combined size of the partial blockages is detected by the magnitude of the zeroth frequency. In addition, special cases of partial blockage are presented to indicate the limitations of the present methodology.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.544887
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 267-271
Titre : Obstacle-Reynolds-number based analysis of local scour at submerged cylinders Type de document : texte imprimé Auteurs : Thomas Euler, Auteur ; Jurgen Herget, Auteur Année de publication : 2011 Article en page(s) : pp. 267-271 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Local scour Obstacle mark Obstacle Reynolds number Open channel flow Submerged obstacle 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 : A simple process-based, analytical approach is developed and validated herein to determine the local scour at obstacles in the fluvial environment. It is based on the obstacle Reynolds and Froude numbers. Clear-water flume experiments were conducted to investigate the local scour depths at submerged cylinders in coarse uniform sand. The resulting scour depths were correlated with an analytical model and validated with two data sets on local scour at submerged and emergent cylinders. The size of the projected frontal obstacle area in relation to the mean flow velocity has a significant effect on the scour hole shape and depth. A power law function is derived that satisfactorily describes the present scour depth data. The approach is limited to near-equilibrium clear-water scour, uniform sediment and excludes particle density effects.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.547719 [article] Obstacle-Reynolds-number based analysis of local scour at submerged cylinders [texte imprimé] / Thomas Euler, Auteur ; Jurgen Herget, Auteur . - 2011 . - pp. 267-271.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 267-271
Mots-clés : Local scour Obstacle mark Obstacle Reynolds number Open channel flow Submerged obstacle 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 : A simple process-based, analytical approach is developed and validated herein to determine the local scour at obstacles in the fluvial environment. It is based on the obstacle Reynolds and Froude numbers. Clear-water flume experiments were conducted to investigate the local scour depths at submerged cylinders in coarse uniform sand. The resulting scour depths were correlated with an analytical model and validated with two data sets on local scour at submerged and emergent cylinders. The size of the projected frontal obstacle area in relation to the mean flow velocity has a significant effect on the scour hole shape and depth. A power law function is derived that satisfactorily describes the present scour depth data. The approach is limited to near-equilibrium clear-water scour, uniform sediment and excludes particle density effects.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2010.547719
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 272-275
Titre : Event flow hydrograph-based method for shear velocity estimation Type de document : texte imprimé Auteurs : Bhuban Ghimire, Auteur ; Deng, Zhi-Qiang, Auteur Année de publication : 2011 Article en page(s) : pp. 272-275 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Friction slope Hydrograph Shear velocity Unsteady flow Wave 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 : Due to the lack of a simple method for finding the shear velocity during flood events, most sediment resuspension or transport models either resort to complex numerical models requiring detailed input data or rely on uniform steady flow formula. Here a practical method for estimating the shear velocity of unsteady flow is presented by using the flow hydrograph and channel geometry data. Using equations for open channel flow, formulas for shear velocity are derived in terms of discharge gradient, representing the friction slope of unsteady flow in prismatic channels. Applications of the new method using published experimental data and simulated results indicate that the method is comparable with existing methods in terms of accuracy but requires less input data. This method is particularly applicable to natural floods in relatively straight reaches of lowland rivers where the non-inertia wave approximation to the Saint-Venant equations is theoretically appropriate.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552463 [article] Event flow hydrograph-based method for shear velocity estimation [texte imprimé] / Bhuban Ghimire, Auteur ; Deng, Zhi-Qiang, Auteur . - 2011 . - pp. 272-275.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 49 N° 2 (Mars/Avril 2011) . - pp. 272-275
Mots-clés : Friction slope Hydrograph Shear velocity Unsteady flow Wave 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 : Due to the lack of a simple method for finding the shear velocity during flood events, most sediment resuspension or transport models either resort to complex numerical models requiring detailed input data or rely on uniform steady flow formula. Here a practical method for estimating the shear velocity of unsteady flow is presented by using the flow hydrograph and channel geometry data. Using equations for open channel flow, formulas for shear velocity are derived in terms of discharge gradient, representing the friction slope of unsteady flow in prismatic channels. Applications of the new method using published experimental data and simulated results indicate that the method is comparable with existing methods in terms of accuracy but requires less input data. This method is particularly applicable to natural floods in relatively straight reaches of lowland rivers where the non-inertia wave approximation to the Saint-Venant equations is theoretically appropriate.
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.552463
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