Dépouillements

An experimental study of effects of step roughness in skimming flows on stepped chutes / Gonzalez, Carlos A. in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 24-35 Titre : An experimental study of effects of step roughness in skimming flows on stepped chutes Titre original : Etude expérimentale des effets de la rugosité des marches sur les écoulements d'écumage dans les évacuateurs en gradins Type de document : texte imprimé Auteurs : Gonzalez, Carlos A., Auteur ; Masayuki Takahashi, Auteur ; Chanson, Hubert, Auteur Article en page(s) : p. 24-35 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Stepped  chute  Skimming  flow  Step  roughness  Air-water  flow  Physical  modelling  Flow  resistance  Form  drag  Energy  dissipation  Gabion  stepped  spillway 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 : On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipater. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com/ [article] An experimental study of effects of step roughness in skimming flows on stepped chutes = Etude expérimentale des effets de la rugosité des marches sur les écoulements d'écumage dans les évacuateurs en gradins [texte imprimé] / Gonzalez, Carlos A., Auteur ; Masayuki Takahashi, Auteur ; Chanson, Hubert, Auteur . - p. 24-35. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 24-35 Mots-clés : Stepped  chute  Skimming  flow  Step  roughness  Air-water  flow  Physical  modelling  Flow  resistance  Form  drag  Energy  dissipation  Gabion  stepped  spillway 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 : On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipater. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com/

Revisiting turbulence in smooth uniform open channel flow / Roussinova Vesselina in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 36-48 Titre : Revisiting turbulence in smooth uniform open channel flow Titre original : Révision de la tubulence dans un écoulement uniforme en canal ouvert lisse Type de document : texte imprimé Auteurs : Roussinova Vesselina, Auteur ; Nihar Biswas, Auteur ; Ram Balachandar, Auteur Article en page(s) : p. 36-48 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Open  channel  flow  Turbulence  Quadrant  analysis  Channel  aspect  ratio 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 reexamines the mean velocity scaling as well as higher order turbulent moments in a uniform smooth open channel flow with three different aspect ratios. In the overlap region, the velocity profiles follow the classical logarithmic law. In the outer region, the mean velocity data at various aspect ratios collapse on to each other only when the length scale is suitably modified. This length scale is defined on the basis of a region of constant turbulence intensity close to the free surface and is equal to the depth of flow at large aspect ratios. The proposed new length scaling also provides for a positive value of the wake parameter. Furthermore, turbulence distributions including that of the Reynolds shear stress, and triple correlations ( and ) collapse onto a single line making them nearly independent of aspect ratio. Quadrant decomposition of the velocity data was used to quantify the differences in the turbulence structure at the three channel aspect ratios. The quadrant analysis shows that the turbulence in open channel is similar to that in both turbulent boundary layers and flow in two-dimensional channels when all turbulent events are included. When only the extreme events are considered, differences between open channel flow and turbulent boundary layers become significant. The conditional quadrant analysis reveals that the violent ejections do penetrate into the flow and they are responsible for producing large portion of the Reynolds shear stress. Some effects of aspect ratio are revealed when the ratio of the ejection to sweep events are calculated. The turbulent events with the higher aspect ratios tend to be closer to the two-dimensional channel data. DEWEY : 627 ISSN : 0022-1686 RAMEAU : Turbulence En ligne : http://www.journalhydraulicresearch.com/ [article] Revisiting turbulence in smooth uniform open channel flow = Révision de la tubulence dans un écoulement uniforme en canal ouvert lisse [texte imprimé] / Roussinova Vesselina, Auteur ; Nihar Biswas, Auteur ; Ram Balachandar, Auteur . - p. 36-48. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 36-48 Mots-clés : Open  channel  flow  Turbulence  Quadrant  analysis  Channel  aspect  ratio 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 reexamines the mean velocity scaling as well as higher order turbulent moments in a uniform smooth open channel flow with three different aspect ratios. In the overlap region, the velocity profiles follow the classical logarithmic law. In the outer region, the mean velocity data at various aspect ratios collapse on to each other only when the length scale is suitably modified. This length scale is defined on the basis of a region of constant turbulence intensity close to the free surface and is equal to the depth of flow at large aspect ratios. The proposed new length scaling also provides for a positive value of the wake parameter. Furthermore, turbulence distributions including that of the Reynolds shear stress, and triple correlations ( and ) collapse onto a single line making them nearly independent of aspect ratio. Quadrant decomposition of the velocity data was used to quantify the differences in the turbulence structure at the three channel aspect ratios. The quadrant analysis shows that the turbulence in open channel is similar to that in both turbulent boundary layers and flow in two-dimensional channels when all turbulent events are included. When only the extreme events are considered, differences between open channel flow and turbulent boundary layers become significant. The conditional quadrant analysis reveals that the violent ejections do penetrate into the flow and they are responsible for producing large portion of the Reynolds shear stress. Some effects of aspect ratio are revealed when the ratio of the ejection to sweep events are calculated. The turbulent events with the higher aspect ratios tend to be closer to the two-dimensional channel data. DEWEY : 627 ISSN : 0022-1686 RAMEAU : Turbulence En ligne : http://www.journalhydraulicresearch.com/

On the location in flow plan of erosion–deposition zones in sine-generated meandering streams / A. M. Ferreira Da Silva in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 49-60 Titre : On the location in flow plan of erosion–deposition zones in sine-generated meandering streams Titre original : Sur la localisation dans le plan d'écoulement des zones d'érosion et de dépôt des courants à méandres Type de document : texte imprimé Auteurs : A. M. Ferreira Da Silva, Auteur ; T. El-Tahawy, Auteur Article en page(s) : p. 49-60 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Sine-generated  meandering  streams  Stream  curvature  Bed  deformation  Laboratory  runs  Location  of  erosion-deposition  zones  Determining  parameters 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 concerns the location in flow plan of the laterally adjacent erosion-deposition zones (“deeps” and “hills”) in sine-generated meandering streams. The aim of the paper is to gain insight into how the location of the aforementioned erosion-deposition zones is affected by stream sinuosity, as well as other geometric and flow-related parameters. For this purpose, a series of movable bed runs is carried out in a sine-generated channel having an intermediate value of the deflection angle , namely . This value extends the range of -values investigated by previous authors, who tended to focus mainly on the limiting cases of “small” and “large” values of ( and ). The runs started from a flat bed, which subsequently was allowed to develop until the equilibrium state, or a near-equilibrium state was achieved. The bed topography maps showing the bed surface at the end of the present runs were analysed together with those from previous authors’ runs. It is found that, all other conditions remaining the same, the -long erosion-deposition zone which in streams having small extends from any apex-section to the next consecutive apex-section , gradually moves upstream as increases from to – so that in the limiting case of large , this erosion-deposition zone extends from the crossover-section to the crossover-section ( and being the upstream- and downstream- crossover sections of the meander loop whose apex-section is ). For any specified , the location of the -long erosion-deposition zones appears to be affected mainly by meander wavelength relative to flow width, and perhaps also by the flow friction factor. A quantity characterizing the different distributions in flow plan of the erosion-deposition zones is introduced, and its mathematical form is investigated. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] On the location in flow plan of erosion–deposition zones in sine-generated meandering streams = Sur la localisation dans le plan d'écoulement des zones d'érosion et de dépôt des courants à méandres [texte imprimé] / A. M. Ferreira Da Silva, Auteur ; T. El-Tahawy, Auteur . - p. 49-60. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 49-60 Mots-clés : Sine-generated  meandering  streams  Stream  curvature  Bed  deformation  Laboratory  runs  Location  of  erosion-deposition  zones  Determining  parameters 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 concerns the location in flow plan of the laterally adjacent erosion-deposition zones (“deeps” and “hills”) in sine-generated meandering streams. The aim of the paper is to gain insight into how the location of the aforementioned erosion-deposition zones is affected by stream sinuosity, as well as other geometric and flow-related parameters. For this purpose, a series of movable bed runs is carried out in a sine-generated channel having an intermediate value of the deflection angle , namely . This value extends the range of -values investigated by previous authors, who tended to focus mainly on the limiting cases of “small” and “large” values of ( and ). The runs started from a flat bed, which subsequently was allowed to develop until the equilibrium state, or a near-equilibrium state was achieved. The bed topography maps showing the bed surface at the end of the present runs were analysed together with those from previous authors’ runs. It is found that, all other conditions remaining the same, the -long erosion-deposition zone which in streams having small extends from any apex-section to the next consecutive apex-section , gradually moves upstream as increases from to – so that in the limiting case of large , this erosion-deposition zone extends from the crossover-section to the crossover-section ( and being the upstream- and downstream- crossover sections of the meander loop whose apex-section is ). For any specified , the location of the -long erosion-deposition zones appears to be affected mainly by meander wavelength relative to flow width, and perhaps also by the flow friction factor. A quantity characterizing the different distributions in flow plan of the erosion-deposition zones is introduced, and its mathematical form is investigated. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

How fast can a river flow over alluvium? / Michel A. Verbanck in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 61.71 Titre : How fast can a river flow over alluvium? Titre original : Y'a t'il une vitesse maximum a laquelle peuvent couler les rivières alluviales? Type de document : texte imprimé Auteurs : Michel A. Verbanck, Auteur Article en page(s) : p. 61.71 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Alluvial  regime  Flow-sediment-morphology  system  Mobile  bedforms  Stationary  inphase  waves  Antidunes  Vortex  drag  model  Separated  and  reattaching  flow  Movable-bed  resistance  Sediment  transport  capacity 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 new “vortex-drag” approach is proposed to compute the rate of dissipation of mean-motion energy in alluvial streams flowing over mobile bed forms. 1D-routing exercises strongly suggest that, for a given depth and energy-slope, there exists a certain flow velocity limit an alluvial stream is unlikely to exceed. This remarkable flow condition would actually correspond to a fundamental mode in terms of vortex Strouhal frequency (to which only higher harmonics can eventually be associated). Interestingly, the maximum possible velocity is not attained over a plane bed, but occurs when the wavy shape of the water-surface remains in phase with the sand wave. The model treats flow over sandy alluvium as a combination of boundary-attached and -detached flow features, both necessary to explain how well-marked protrusions can develop spontaneously in the bed profile and be maintained in response to extreme water-sediment discharge and stream power conditions. Through the vortex-drag concept and its athematical development, a lot is learned about the nature of the mutual interactions existing between the various alluvial processes: bedform development, alluvial channel resistance, sediment transport capacity and turbulence-damping. Bedform types occurring in the upper alluvial regime are at the center of the analysis. Based on the model and on confrontation with available experimental evidence, it is suggested that the inphase wave [IPW] flow configuration is associated with minimum possible drag, creating low-turbulence high-velocity conditions ideal to evacuate extreme river discharges. Occurrence of IPW conditions is therefore important in terms of flooding alleviation, but will develop only if the right type of sediment is maintained available on the stream bed. The boundary-attached component of the model introduces a generalized Froude number formulation in alluvial hydraulics, to represent topographically-forced gravity waves occurring in non-shallow environments such as ripple fields. For the boundary-detached component of the model, we introduce a “control factor m” (m ≥ 1) which reflects a complex feedback-control loop process active in the separation cell immediately downstream of the bedform crest. Lift-up of bed particles (under the action of the corresponding vortices shedding out of the reattachment region) implies that control factor m should also play an important role in the further development of bursting-based conceptual models of non-cohesive sediment transport. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] How fast can a river flow over alluvium? = Y'a t'il une vitesse maximum a laquelle peuvent couler les rivières alluviales? [texte imprimé] / Michel A. Verbanck, Auteur . - p. 61.71. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 61.71 Mots-clés : Alluvial  regime  Flow-sediment-morphology  system  Mobile  bedforms  Stationary  inphase  waves  Antidunes  Vortex  drag  model  Separated  and  reattaching  flow  Movable-bed  resistance  Sediment  transport  capacity 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 new “vortex-drag” approach is proposed to compute the rate of dissipation of mean-motion energy in alluvial streams flowing over mobile bed forms. 1D-routing exercises strongly suggest that, for a given depth and energy-slope, there exists a certain flow velocity limit an alluvial stream is unlikely to exceed. This remarkable flow condition would actually correspond to a fundamental mode in terms of vortex Strouhal frequency (to which only higher harmonics can eventually be associated). Interestingly, the maximum possible velocity is not attained over a plane bed, but occurs when the wavy shape of the water-surface remains in phase with the sand wave. The model treats flow over sandy alluvium as a combination of boundary-attached and -detached flow features, both necessary to explain how well-marked protrusions can develop spontaneously in the bed profile and be maintained in response to extreme water-sediment discharge and stream power conditions. Through the vortex-drag concept and its athematical development, a lot is learned about the nature of the mutual interactions existing between the various alluvial processes: bedform development, alluvial channel resistance, sediment transport capacity and turbulence-damping. Bedform types occurring in the upper alluvial regime are at the center of the analysis. Based on the model and on confrontation with available experimental evidence, it is suggested that the inphase wave [IPW] flow configuration is associated with minimum possible drag, creating low-turbulence high-velocity conditions ideal to evacuate extreme river discharges. Occurrence of IPW conditions is therefore important in terms of flooding alleviation, but will develop only if the right type of sediment is maintained available on the stream bed. The boundary-attached component of the model introduces a generalized Froude number formulation in alluvial hydraulics, to represent topographically-forced gravity waves occurring in non-shallow environments such as ripple fields. For the boundary-detached component of the model, we introduce a “control factor m” (m ≥ 1) which reflects a complex feedback-control loop process active in the separation cell immediately downstream of the bedform crest. Lift-up of bed particles (under the action of the corresponding vortices shedding out of the reattachment region) implies that control factor m should also play an important role in the further development of bursting-based conceptual models of non-cohesive sediment transport. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Finite volume model for steady-state transverse mixing in streams / Z. Ahmed in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 72-80 Titre : Finite volume model for steady-state transverse mixing in streams Titre original : Modèle en volume fini pour le mélange transversal dans les courants en régime permanent Type de document : texte imprimé Auteurs : Z. Ahmed, Auteur Article en page(s) : p. 72-80 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Stream  Polluant  Transverse  mixing  Finite  volume  method  Mixing  coefficient 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 : Transverse mixing is arguably more important in water quality management than either vertical or longitudinal mixing, especially when dealing with the discharge of pollutants from point sources or the mixing of tributary inflows. A finite volume model with upwind scheme is developed to solve the equation for transverse mixing in steady flow in prismatic channel. The model takes care of variation of transverse mixing coefficient across the channel width. The model has been verified with analytical solutions for constant mixing coefficient and for pollutant injection in the middle and near the bank of streams. The model is inherently mass conservative and captures successfully the discontinuity existing at the upstream boundary. Effect of variable transverse mixing coefficient on the pollutant concentration profiles has been shown for a typical cross-section of the Lesser Slave River. It is found that the computed concentration profiles for variable transverse mixing coefficient are significantly different from those for constant coefficient. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Finite volume model for steady-state transverse mixing in streams = Modèle en volume fini pour le mélange transversal dans les courants en régime permanent [texte imprimé] / Z. Ahmed, Auteur . - p. 72-80. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 72-80 Mots-clés : Stream  Polluant  Transverse  mixing  Finite  volume  method  Mixing  coefficient 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 : Transverse mixing is arguably more important in water quality management than either vertical or longitudinal mixing, especially when dealing with the discharge of pollutants from point sources or the mixing of tributary inflows. A finite volume model with upwind scheme is developed to solve the equation for transverse mixing in steady flow in prismatic channel. The model takes care of variation of transverse mixing coefficient across the channel width. The model has been verified with analytical solutions for constant mixing coefficient and for pollutant injection in the middle and near the bank of streams. The model is inherently mass conservative and captures successfully the discontinuity existing at the upstream boundary. Effect of variable transverse mixing coefficient on the pollutant concentration profiles has been shown for a typical cross-section of the Lesser Slave River. It is found that the computed concentration profiles for variable transverse mixing coefficient are significantly different from those for constant coefficient. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Experimental study of the flow field with spilling type breaking / Mossa, Michele in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 81-86 Titre : Experimental study of the flow field with spilling type breaking Titre original : Etude expérimentale d'un champ d'écoulement avec un déferlement déversant Type de document : texte imprimé Auteurs : Mossa, Michele, Auteur Article en page(s) : p. 81-86 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Spilling  breaking  Turbulence  Hydrofoil  LDA  Mixing  layer  Wake 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 shows the results of an experimental work on the spilling type breaking flow field produced by a hydrofoil positioned in a uniform current. From the examination of the Laser Doppler Anemometer results downstream of the hydrofoil a flow field similar to a mixing layer, close to the breaking zone, and a flow field similar to a wake were found. The conclusions that can be drawn by the studies conducted can be summarized as follows: (i) downstream of the hydrofoil it is possible to distinguish two regions of flow, namely one immediately downstream of the hydrofoil, including spilling characterized by a mixing of water and air, and one downstream of the same spilling; (ii) in first of the aforementioned regions the flow is similar to that of a mixing layer, while, in the downstream region, it shows conditions similar to a wake; (iii) the experiments furnish information on the turbulence characteristics in the two regions, and extract the zone where the wake effect can be considered negligible; (iv) the time-averaged free surface height presents a decreasing trend from the wake origin. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Experimental study of the flow field with spilling type breaking = Etude expérimentale d'un champ d'écoulement avec un déferlement déversant [texte imprimé] / Mossa, Michele, Auteur . - p. 81-86. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 81-86 Mots-clés : Spilling  breaking  Turbulence  Hydrofoil  LDA  Mixing  layer  Wake 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 shows the results of an experimental work on the spilling type breaking flow field produced by a hydrofoil positioned in a uniform current. From the examination of the Laser Doppler Anemometer results downstream of the hydrofoil a flow field similar to a mixing layer, close to the breaking zone, and a flow field similar to a wake were found. The conclusions that can be drawn by the studies conducted can be summarized as follows: (i) downstream of the hydrofoil it is possible to distinguish two regions of flow, namely one immediately downstream of the hydrofoil, including spilling characterized by a mixing of water and air, and one downstream of the same spilling; (ii) in first of the aforementioned regions the flow is similar to that of a mixing layer, while, in the downstream region, it shows conditions similar to a wake; (iii) the experiments furnish information on the turbulence characteristics in the two regions, and extract the zone where the wake effect can be considered negligible; (iv) the time-averaged free surface height presents a decreasing trend from the wake origin. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Propagation of non-linear transient pressures through fresh and sea water / Gerald Muller in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 87-95 Titre : Propagation of non-linear transient pressures through fresh and sea water Titre original : Propagation de pressions transitoires non linéaires en eau douce et eau de mer Type de document : texte imprimé Auteurs : Gerald Muller, Auteur ; Peter Geisenhainer, Auteur ; Guido Wolters, Auteur Article en page(s) : p. 87-95 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Pressure  propagation  Cavitation  Fresh  water  Sea  water  Coastal  structures 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 propagation of pressures generated by wave or jet impact into water filled cracks and fissures can create internal bursting pressures and resulting damages in structures such as blockwork breakwaters or coastal rock cliffs. Experimental investigations of pressure pulse propagation showed that the pressure pulses travelled as elastic waves in a water–air mixture inside of the cracks. Most previous experimental investigations were conducted at small scale, with near linear air compressibility. In reality, pressures will be well above atmospheric pressure so that non-linear effects can be expected. A series of drop tests was conducted to investigate the characteristics of pressure pulse propagation in the non-linear range of air compressibility in fresh and sea water. It was found that with pressure magnitudes exceeding approximately 100 kPa, the pulses become distinctly non-linear, with steep and short peaks and long, shallow troughs. The speed of propagation in fresh water ranged from 300 to 400 m/s, indicating air contents of 0.11 to 0.07% air. In sea water, the speed of propagation reached 290 m/s, indicating a slightly larger resident air content of 0.12%. Cavitation occurred and was accompanied in fresh water by short pressure bursts, which could not be observed in sea water. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Propagation of non-linear transient pressures through fresh and sea water = Propagation de pressions transitoires non linéaires en eau douce et eau de mer [texte imprimé] / Gerald Muller, Auteur ; Peter Geisenhainer, Auteur ; Guido Wolters, Auteur . - p. 87-95. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 87-95 Mots-clés : Pressure  propagation  Cavitation  Fresh  water  Sea  water  Coastal  structures 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 propagation of pressures generated by wave or jet impact into water filled cracks and fissures can create internal bursting pressures and resulting damages in structures such as blockwork breakwaters or coastal rock cliffs. Experimental investigations of pressure pulse propagation showed that the pressure pulses travelled as elastic waves in a water–air mixture inside of the cracks. Most previous experimental investigations were conducted at small scale, with near linear air compressibility. In reality, pressures will be well above atmospheric pressure so that non-linear effects can be expected. A series of drop tests was conducted to investigate the characteristics of pressure pulse propagation in the non-linear range of air compressibility in fresh and sea water. It was found that with pressure magnitudes exceeding approximately 100 kPa, the pulses become distinctly non-linear, with steep and short peaks and long, shallow troughs. The speed of propagation in fresh water ranged from 300 to 400 m/s, indicating air contents of 0.11 to 0.07% air. In sea water, the speed of propagation reached 290 m/s, indicating a slightly larger resident air content of 0.12%. Cavitation occurred and was accompanied in fresh water by short pressure bursts, which could not be observed in sea water. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Uncertainty assessment: application to the shoreline / A. Payo in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 96-104 Titre : Uncertainty assessment: application to the shoreline Titre original : Evaluation d'incertitude: application au littoral Type de document : texte imprimé Auteurs : A. Payo, Auteur ; A. Baquerizo, Auteur ; M. Losada, Auteur Article en page(s) : p. 96-104 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : One-line  Empirical  orthogonal  functions  Monte-Carlo  method  Strom-event  sequences 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 : It is impossible to know beforehand the planforms of a stretch of beach without being first aware of the maritime climate affecting it. This article describes a procedure for objectively calculating the uncertainty associated with the prediction of the evolution of a stretch of beach in terms of probability. On the basis of oceanographic data records as well as empirical orthogonal functions (EOF), we propose a procedure for the simulation of possible sequences of storm events. Such sequences were then entered as input for a morphodynamic model with a view to the subsequent generation of possible planforms. EOF methodology was then used to estimate the probability of each of the planforms thus generated. The case study presented here is that of the evolution of an initially straight sand beach where a rectangular tapered fill had been constructed. The beach is located upshore of a groin perpendicular to the coastline, and had blocked all longshore sediment transport. For this analysis we used a one-line model with time-dependent boundary conditions and a non-homogeneous diffusion coefficient. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com/ [article] Uncertainty assessment: application to the shoreline = Evaluation d'incertitude: application au littoral [texte imprimé] / A. Payo, Auteur ; A. Baquerizo, Auteur ; M. Losada, Auteur . - p. 96-104. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 96-104 Mots-clés : One-line  Empirical  orthogonal  functions  Monte-Carlo  method  Strom-event  sequences 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 : It is impossible to know beforehand the planforms of a stretch of beach without being first aware of the maritime climate affecting it. This article describes a procedure for objectively calculating the uncertainty associated with the prediction of the evolution of a stretch of beach in terms of probability. On the basis of oceanographic data records as well as empirical orthogonal functions (EOF), we propose a procedure for the simulation of possible sequences of storm events. Such sequences were then entered as input for a morphodynamic model with a view to the subsequent generation of possible planforms. EOF methodology was then used to estimate the probability of each of the planforms thus generated. The case study presented here is that of the evolution of an initially straight sand beach where a rectangular tapered fill had been constructed. The beach is located upshore of a groin perpendicular to the coastline, and had blocked all longshore sediment transport. For this analysis we used a one-line model with time-dependent boundary conditions and a non-homogeneous diffusion coefficient. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com/

Sheared and un-sheared segregation and settling behaviour of fine sand particles in hyperconcentrated homogeneous sand-water mixture flows / Behnam Pirouz in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 105-111 Titre : Sheared and un-sheared segregation and settling behaviour of fine sand particles in hyperconcentrated homogeneous sand-water mixture flows Titre original : Ségrégation cisaillée ou non et comportement du dépôt des particules fines dans les écoulements hyperconcentrés homogènes de mélange eau-sable Type de document : texte imprimé Auteurs : Behnam Pirouz, Auteur ; Mohammad Reza Kavianpour, Auteur ; Paul Williams, Auteur Article en page(s) : p. 105-111 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Hyperconcentrated  flow  Segregation  Settling  Hydraulic  sorting  Slurry  Tailings  Equilibrium  slope  Hydraulic  fill 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 : Segregation and settling of fine solids particles in hyperconcentrated homogeneous sand-water mixtures were studied for un-sheared and sheared conditions in settling columns in the laboratory. Specific solids percent values were able to be determined as the segregation threshold limit for un-sheared static settling conditions as well as for sheared settling with different rates of shear. Full-scale flume tests were also performed in the field with mine tailings slurry to study the settling and segregation behaviour of fine sand particles in the flow of a hyperconcentrated sand-water mixture under equilibrium slope conditions. The solids contents of slurry mixtures were within the range 44 to 58% (by weight). The solids particles in the slurries had D50 = 10 μm. Experimental results showed that increasing the shear rate in the settling column up to a certain level had the effect of increasing the segregation threshold limit value. Slurry density in hyperconcentrated flow remained constant with depth. Although the flow of the hyperconcentrated mixture under equilibrium slope condition was shown to be total transport flow, further detailed grain size analysis revealed that there was always a slightly higher portion of coarse solids particles that tended to accumulate towards the bottom of the flow. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Sheared and un-sheared segregation and settling behaviour of fine sand particles in hyperconcentrated homogeneous sand-water mixture flows = Ségrégation cisaillée ou non et comportement du dépôt des particules fines dans les écoulements hyperconcentrés homogènes de mélange eau-sable [texte imprimé] / Behnam Pirouz, Auteur ; Mohammad Reza Kavianpour, Auteur ; Paul Williams, Auteur . - p. 105-111. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 105-111 Mots-clés : Hyperconcentrated  flow  Segregation  Settling  Hydraulic  sorting  Slurry  Tailings  Equilibrium  slope  Hydraulic  fill 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 : Segregation and settling of fine solids particles in hyperconcentrated homogeneous sand-water mixtures were studied for un-sheared and sheared conditions in settling columns in the laboratory. Specific solids percent values were able to be determined as the segregation threshold limit for un-sheared static settling conditions as well as for sheared settling with different rates of shear. Full-scale flume tests were also performed in the field with mine tailings slurry to study the settling and segregation behaviour of fine sand particles in the flow of a hyperconcentrated sand-water mixture under equilibrium slope conditions. The solids contents of slurry mixtures were within the range 44 to 58% (by weight). The solids particles in the slurries had D50 = 10 μm. Experimental results showed that increasing the shear rate in the settling column up to a certain level had the effect of increasing the segregation threshold limit value. Slurry density in hyperconcentrated flow remained constant with depth. Although the flow of the hyperconcentrated mixture under equilibrium slope condition was shown to be total transport flow, further detailed grain size analysis revealed that there was always a slightly higher portion of coarse solids particles that tended to accumulate towards the bottom of the flow. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Pulsating turbulent flow in a straight asymmetric diffuser / Cervantes, Michel J. in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 112-128 Titre : Pulsating turbulent flow in a straight asymmetric diffuser Titre original : Ecoulement turbulent pulsé dans un diffuseur asymétrique droit Type de document : texte imprimé Auteurs : Cervantes, Michel J., Auteur ; Fredrik T. Engstrom, Auteur Article en page(s) : p. 112-128 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Unsteady  Turbulent  Boundary  Diffuser 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 : Pulsating turbulent flow is studied for four regimes: steady, quasi-steady, relaxation, and quasi-laminar in a rectangular straight asymmetric diffuser, a generic model of the diffuser found at the end of most Kaplan and Francis type hydropower turbines. The flow entering the diffuser is a developing duct flow at Reynolds number 20 000, based on mean streamwise velocity and hydraulic diameter. The time averaged velocity and turbulent quantities are not affected by the forced oscillation. The regimes prevail in the diffuser, but are shifted due to the decreasing friction velocity. The oscillating quantities are affected by the adverse pressure gradient in the same way as the time averaged quantities, but with a decreasing effect for higher forcing frequencies. The amplitude of the oscillating wall shear stress is found to be signicantly lower than the Stokes solution in the quasi-laminar regime. The regime is confirmed by the behaviour of several other quantities. The pressure recovery is found to be 30 % higher in the relaxation regime than in the other regimes. Results are compared with experiments in channels and turbulent boundary layers, with and without an adverse pressure gradient, and with large-eddy simulations. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Pulsating turbulent flow in a straight asymmetric diffuser = Ecoulement turbulent pulsé dans un diffuseur asymétrique droit [texte imprimé] / Cervantes, Michel J., Auteur ; Fredrik T. Engstrom, Auteur . - p. 112-128. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 112-128 Mots-clés : Unsteady  Turbulent  Boundary  Diffuser 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 : Pulsating turbulent flow is studied for four regimes: steady, quasi-steady, relaxation, and quasi-laminar in a rectangular straight asymmetric diffuser, a generic model of the diffuser found at the end of most Kaplan and Francis type hydropower turbines. The flow entering the diffuser is a developing duct flow at Reynolds number 20 000, based on mean streamwise velocity and hydraulic diameter. The time averaged velocity and turbulent quantities are not affected by the forced oscillation. The regimes prevail in the diffuser, but are shifted due to the decreasing friction velocity. The oscillating quantities are affected by the adverse pressure gradient in the same way as the time averaged quantities, but with a decreasing effect for higher forcing frequencies. The amplitude of the oscillating wall shear stress is found to be signicantly lower than the Stokes solution in the quasi-laminar regime. The regime is confirmed by the behaviour of several other quantities. The pressure recovery is found to be 30 % higher in the relaxation regime than in the other regimes. Results are compared with experiments in channels and turbulent boundary layers, with and without an adverse pressure gradient, and with large-eddy simulations. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Systematic exploration of pipeline network calibration using transients / B. S. Jung in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 129-137 Titre : Systematic exploration of pipeline network calibration using transients Titre original : Exploration systématique du calibrage d'un réseau de canalisations en utilisant des coupures Type de document : texte imprimé Auteurs : B. S. Jung, Auteur ; B. W. Karney, Auteur Article en page(s) : p. 129-137 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Water  distribution  system  Calibration  Inverse  transient  analysis  Sensitivity  analysis  Evolutionary  optimization  Particle  swam  optimization  Genetic  algorithm 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 : Accurate information of pipeline and system properties is crucially important for precise computer simulation of pipe networks. Even though inverse transient analysis (ITA) techniques have been widely investigated for leak detection and friction factor calibration, many challenges still remain. One reason for these difficulties is that real water distribution systems invariably have many kinds of uncertainties including pipe diameter, wave speed and the water demand at the time of the tests. This paper investigates quantitatively how inaccuracies in such values invariably deteriorate the performance of calibration approaches. Thus, the paper argues that a systematic calibration should explicitly include these additional uncertainties during the ITA process. Two evolutionary approaches, namely Genetic Algorithms and Particle Swarm Optimization, are applied and are both compared and contrasted during the ITA iterations. The evolutionary algorithms help the search escape from poor local optima in multifaceted and complex problems and thus assist in locating global (or near-global) optima. However, most current approaches are shown to converge poorly as the full scale of the typical field problems is progressively reflected in the search space. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Systematic exploration of pipeline network calibration using transients = Exploration systématique du calibrage d'un réseau de canalisations en utilisant des coupures [texte imprimé] / B. S. Jung, Auteur ; B. W. Karney, Auteur . - p. 129-137. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 129-137 Mots-clés : Water  distribution  system  Calibration  Inverse  transient  analysis  Sensitivity  analysis  Evolutionary  optimization  Particle  swam  optimization  Genetic  algorithm 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 : Accurate information of pipeline and system properties is crucially important for precise computer simulation of pipe networks. Even though inverse transient analysis (ITA) techniques have been widely investigated for leak detection and friction factor calibration, many challenges still remain. One reason for these difficulties is that real water distribution systems invariably have many kinds of uncertainties including pipe diameter, wave speed and the water demand at the time of the tests. This paper investigates quantitatively how inaccuracies in such values invariably deteriorate the performance of calibration approaches. Thus, the paper argues that a systematic calibration should explicitly include these additional uncertainties during the ITA process. Two evolutionary approaches, namely Genetic Algorithms and Particle Swarm Optimization, are applied and are both compared and contrasted during the ITA iterations. The evolutionary algorithms help the search escape from poor local optima in multifaceted and complex problems and thus assist in locating global (or near-global) optima. However, most current approaches are shown to converge poorly as the full scale of the typical field problems is progressively reflected in the search space. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Leak detection in pipelines by frequency response method / Ahmed M. Sattar in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 138-151 Titre : Leak detection in pipelines by frequency response method Titre original : La détection de fuite dans les canalisations par la méthode de réponse en fréquence Type de document : texte imprimé Auteurs : Ahmed M. Sattar, Auteur ; M. Hanif Chaudhry, Auteur Article en page(s) : p. 138-151 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Leak-steady  oscillatory  Pipelines  Transfer  matrix  Frequency  reponse  Amplitude  of  pressure  oscillations  Even  harmonics 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 new technique for the detection of leaks in a pipeline is presented utilizing its frequency response. In the system frequency response, a leak increases the amplitude of pressure oscillations at the even harmonics. Such an increase in amplitude has an oscillatory pattern; the frequency and amplitude of this pattern may be utilized to predict the Location and discharge of a leak. In this technique, the pressure transient history at one location is sufficient and the history of the transient in the pipe prior to leak is not needed; this makes it advantageous over a number of other existing techniques, in addition to being simpler to use. It is shown that the technique successfully detects the location of a leak in a number of simple systems with leak discharge as low as 0.2% of the steady discharge. The technique is verified by comparing the results with those computed by using the method of characteristics. Practical issues and limitations for field implementations are discussed. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Leak detection in pipelines by frequency response method = La détection de fuite dans les canalisations par la méthode de réponse en fréquence [texte imprimé] / Ahmed M. Sattar, Auteur ; M. Hanif Chaudhry, Auteur . - p. 138-151. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 138-151 Mots-clés : Leak-steady  oscillatory  Pipelines  Transfer  matrix  Frequency  reponse  Amplitude  of  pressure  oscillations  Even  harmonics 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 new technique for the detection of leaks in a pipeline is presented utilizing its frequency response. In the system frequency response, a leak increases the amplitude of pressure oscillations at the even harmonics. Such an increase in amplitude has an oscillatory pattern; the frequency and amplitude of this pattern may be utilized to predict the Location and discharge of a leak. In this technique, the pressure transient history at one location is sufficient and the history of the transient in the pipe prior to leak is not needed; this makes it advantageous over a number of other existing techniques, in addition to being simpler to use. It is shown that the technique successfully detects the location of a leak in a number of simple systems with leak discharge as low as 0.2% of the steady discharge. The technique is verified by comparing the results with those computed by using the method of characteristics. Practical issues and limitations for field implementations are discussed. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

A control tool for irrigation canals with scheduled demands / J. Soler Guitart in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 152-167 Titre : A control tool for irrigation canals with scheduled demands Titre original : Un outil de pilotage des canaux d'irrigation pour des demandes programmées Type de document : texte imprimé Auteurs : J. Soler Guitart, Auteur ; M. Gomez Valentin, Auteur ; J. Rodellar Benede, Auteur Article en page(s) : p. 152-167 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Non-linear  predictive  control  Optimization  Irrigation  canals  Water  resources  Flow  transient  prediction 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 problem of adjusting the discharges of a free surface flow canal to meet demand by farmers at particular diversion points requires a certain ability to control the canal and also needs a study of flow transients. This article presents an algorithm for feed forward control of the free surface flow in canals based on computational techniques for optimizing problem-solving in unsteady conditions. Once the irrigation demands in a given period of time are known, this algorithm makes it possible to define the movements of all the gates in the canal so as to provide the required discharge at the required time, thereby optimizing use of the volumes of water involved. Use of the algorithm is illustrated by solving two classical canal control problems. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] A control tool for irrigation canals with scheduled demands = Un outil de pilotage des canaux d'irrigation pour des demandes programmées [texte imprimé] / J. Soler Guitart, Auteur ; M. Gomez Valentin, Auteur ; J. Rodellar Benede, Auteur . - p. 152-167. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 152-167 Mots-clés : Non-linear  predictive  control  Optimization  Irrigation  canals  Water  resources  Flow  transient  prediction 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 problem of adjusting the discharges of a free surface flow canal to meet demand by farmers at particular diversion points requires a certain ability to control the canal and also needs a study of flow transients. This article presents an algorithm for feed forward control of the free surface flow in canals based on computational techniques for optimizing problem-solving in unsteady conditions. Once the irrigation demands in a given period of time are known, this algorithm makes it possible to define the movements of all the gates in the canal so as to provide the required discharge at the required time, thereby optimizing use of the volumes of water involved. Use of the algorithm is illustrated by solving two classical canal control problems. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Fall velocities of natural sediment particles: a simple mathematical presentation of the fall velocity / K. She in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 168-174 Titre : Fall velocities of natural sediment particles: a simple mathematical presentation of the fall velocity Type de document : texte imprimé Auteurs : K. She, Auteur ; L. Trim, Auteur ; D. Pope, Auteur Article en page(s) : p. 168-174 Note générale : Hydraulique Discussion Langues : Anglais (eng) Mots-clés : Fall  velocities  Sediment  particles 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 fall velocity of coastal or river sediment is usually calculated by literature formulas. Many authors have highlighted that this procedure is not really suitable for evaluating the average fall velocity of the natural sediment as a whole. A direct measurement of the sediment samples is recommended. A large number of tests with different sands setting tube diameters, fallings heights and sand concentration have been investigated. Suggestions for a correct use of the settlings tube are made. Measurements on 23 sands (three of them shingles), improved the Eq. (3) proposed by She et al. (2005), showwing that it could be a promising formula to calculate the average fall velocity of natural sands. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Fall velocities of natural sediment particles: a simple mathematical presentation of the fall velocity [texte imprimé] / K. She, Auteur ; L. Trim, Auteur ; D. Pope, Auteur . - p. 168-174. Hydraulique Discussion Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 168-174 Mots-clés : Fall  velocities  Sediment  particles 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 fall velocity of coastal or river sediment is usually calculated by literature formulas. Many authors have highlighted that this procedure is not really suitable for evaluating the average fall velocity of the natural sediment as a whole. A direct measurement of the sediment samples is recommended. A large number of tests with different sands setting tube diameters, fallings heights and sand concentration have been investigated. Suggestions for a correct use of the settlings tube are made. Measurements on 23 sands (three of them shingles), improved the Eq. (3) proposed by She et al. (2005), showwing that it could be a promising formula to calculate the average fall velocity of natural sands. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

Experimental study of transition and skimming flows on stepped spillways in RCC dams: qualitative analysis and pressure measurements / M. Sanches-Juny in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 175-176 Titre : Experimental study of transition and skimming flows on stepped spillways in RCC dams: qualitative analysis and pressure measurements Type de document : texte imprimé Auteurs : M. Sanches-Juny, Auteur ; Dolz, J., Auteur Article en page(s) : p. 175-176 Note générale : Hydraulique Discussion Langues : Anglais (eng) Mots-clés : Skimming  flows  Spillways  Dams 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 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com [article] Experimental study of transition and skimming flows on stepped spillways in RCC dams: qualitative analysis and pressure measurements [texte imprimé] / M. Sanches-Juny, Auteur ; Dolz, J., Auteur . - p. 175-176. Hydraulique Discussion Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 175-176 Mots-clés : Skimming  flows  Spillways  Dams 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 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com

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