Dépouillements

Coherent structures in flow over hydraulic engineering surfaces / Ronald J. Adrian in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 451-464 Titre : Coherent structures in flow over hydraulic engineering surfaces Type de document : texte imprimé Auteurs : Ronald J. Adrian, Auteur ; Ivan Marusic, Auteur Année de publication : 2012 Article en page(s) : pp. 451-464 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Coherent  structures  Reynolds  number  effects  Roughness  Wall  turbulence Résumé : Wall-bounded turbulence manifests itself in a broad range of applications, not least in hydraulic systems. Here, we briefly review the significant advances over the past few decades in the fundamental study of wall turbulence over smooth and rough surfaces, with an emphasis on coherent structures and their role at high Reynolds numbers. We attempt to relate these findings to parallel efforts in the hydraulic engineering community and discuss the implications of coherent structures in important hydraulic phenomena. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/full/10.1080/00221686.2012.729540 [article] Coherent structures in flow over hydraulic engineering surfaces [texte imprimé] / Ronald J. Adrian, Auteur ; Ivan Marusic, Auteur . - 2012 . - pp. 451-464. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 451-464 Mots-clés : Coherent  structures  Reynolds  number  effects  Roughness  Wall  turbulence Résumé : Wall-bounded turbulence manifests itself in a broad range of applications, not least in hydraulic systems. Here, we briefly review the significant advances over the past few decades in the fundamental study of wall turbulence over smooth and rough surfaces, with an emphasis on coherent structures and their role at high Reynolds numbers. We attempt to relate these findings to parallel efforts in the hydraulic engineering community and discuss the implications of coherent structures in important hydraulic phenomena. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/full/10.1080/00221686.2012.729540

Vortex organization in a turbulent boundary layer overlying sparse roughness elements / Michele Guala in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 465-481 Titre : Vortex organization in a turbulent boundary layer overlying sparse roughness elements Type de document : texte imprimé Auteurs : Michele Guala, Auteur ; Christopher D. Tomkins, Auteur ; Kenneth T. Christensen, Auteur Année de publication : 2012 Article en page(s) : pp. 465-481 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bed  roughness  Boundary  layer  turbulence  Particle  image  velocimetry  Wall-bounded  shear  flow  turbulence Résumé : Vortex organization in the outer layer of a turbulent boundary layer overlying sparse, hemispherical roughness elements is explored with two-component particle-image velocimetry (PIV) in multiple streamwise–wall-normal measurement planes downstream and between elements. The presence of sparse roughness elements causes a shortening of the streamwise length scale in the near-wall region. These measurements confirm that vortex packets exist in the outer layer of flow over rough walls, but that their organization is altered, and this is interpreted as the underlying cause of the length-scale reduction. In particular, the elements shed vortices which appear to align in the near-wall region, but are distinct from the packets. Further, it is observed that ejection events triggered in the element wakes are more intense compared to the ejection events in smooth wall. We speculate that this may initiate a self-sustaining mechanism leading to the formation of hairpin packets as a much more effective instability compared to those typical of smooth-wall turbulence. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.729229 [article] Vortex organization in a turbulent boundary layer overlying sparse roughness elements [texte imprimé] / Michele Guala, Auteur ; Christopher D. Tomkins, Auteur ; Kenneth T. Christensen, Auteur . - 2012 . - pp. 465-481. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 465-481 Mots-clés : Bed  roughness  Boundary  layer  turbulence  Particle  image  velocimetry  Wall-bounded  shear  flow  turbulence Résumé : Vortex organization in the outer layer of a turbulent boundary layer overlying sparse, hemispherical roughness elements is explored with two-component particle-image velocimetry (PIV) in multiple streamwise–wall-normal measurement planes downstream and between elements. The presence of sparse roughness elements causes a shortening of the streamwise length scale in the near-wall region. These measurements confirm that vortex packets exist in the outer layer of flow over rough walls, but that their organization is altered, and this is interpreted as the underlying cause of the length-scale reduction. In particular, the elements shed vortices which appear to align in the near-wall region, but are distinct from the packets. Further, it is observed that ejection events triggered in the element wakes are more intense compared to the ejection events in smooth wall. We speculate that this may initiate a self-sustaining mechanism leading to the formation of hairpin packets as a much more effective instability compared to those typical of smooth-wall turbulence. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.729229

Turbulence statistics in compound channels with deep and shallow overbank flows / Sibel Kara in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 482-493 Titre : Turbulence statistics in compound channels with deep and shallow overbank flows Type de document : texte imprimé Auteurs : Sibel Kara, Auteur ; Thorsten Stoesser, Auteur ; Terry W. Sturm, Auteur Année de publication : 2012 Article en page(s) : pp. 482-493 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Apparent  shear  stress  Compound  open  channel  flow  Large  eddy  simulation  Streamwise  momentum  balance  Turbulence-driven  secondary  flow Résumé : The results of large eddy simulations (LESs) of turbulent flow in a compound open channel with deep and shallow flood plain depths are presented. These LESs are validated with experimental data, resulting in a good agreement between measured and calculated data. The floodplain-depth-to-main-channel-depth ratio is an important parameter affecting first- and second-order turbulence statistics. The streamwise momentum balance is analysed with respect to the momentum transfer at the interface between the main channel and the floodplain. Depth-averaging of the streamwise momentum equation reveals the dominance of turbulent shear stress terms in the main channel and of secondary currents in the floodplain. Comparisons of the LES results with an analytical solution of the depth-averaged streamwise momentum equation that demonstrate the importance of case-specific calibration of the parameters of the analytical solution. The turbulence anisotropy is quantified and its role in generating secondary currents is illustrated. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.724194 [article] Turbulence statistics in compound channels with deep and shallow overbank flows [texte imprimé] / Sibel Kara, Auteur ; Thorsten Stoesser, Auteur ; Terry W. Sturm, Auteur . - 2012 . - pp. 482-493. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 482-493 Mots-clés : Apparent  shear  stress  Compound  open  channel  flow  Large  eddy  simulation  Streamwise  momentum  balance  Turbulence-driven  secondary  flow Résumé : The results of large eddy simulations (LESs) of turbulent flow in a compound open channel with deep and shallow flood plain depths are presented. These LESs are validated with experimental data, resulting in a good agreement between measured and calculated data. The floodplain-depth-to-main-channel-depth ratio is an important parameter affecting first- and second-order turbulence statistics. The streamwise momentum balance is analysed with respect to the momentum transfer at the interface between the main channel and the floodplain. Depth-averaging of the streamwise momentum equation reveals the dominance of turbulent shear stress terms in the main channel and of secondary currents in the floodplain. Comparisons of the LES results with an analytical solution of the depth-averaged streamwise momentum equation that demonstrate the importance of case-specific calibration of the parameters of the analytical solution. The turbulence anisotropy is quantified and its role in generating secondary currents is illustrated. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.724194

A family of explicit algebraic models for reynolds stresses and passive scalar fluxes / Martin Ferrand in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 494-505 Titre : A family of explicit algebraic models for reynolds stresses and passive scalar fluxes Type de document : texte imprimé Auteurs : Martin Ferrand, Auteur ; Violeau, Damien, Auteur Année de publication : 2012 Article en page(s) : pp. 494-505 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Explicit  algebraic  model  Passive  scalar  Reynolds  stress  Turbulence  Turbulent  flux Résumé : A family of explicit algebraic models for Reynolds stresses and passive scalar fluxes is proposed and a few variants are discussed, according to the selected set of model constants. Validation is attempted against direct numerical simulation in a steady closed-channel flow for two values of the Reynolds number, indicating the ability of the model to reasonably predict the anisotropy tensor and the scalar flux components when considering wall functions to account for near-wall effects. The production of turbulent kinetic energy is well predicted, while the neutral turbulent Prandtl number has values in agreement with the literature. The proposed model is then compared with an experiment on a heated cylinder with slight temperature variations, with satisfactory results. The proposed model can be applied to various 2D simply-sheared flows involving a passive scalar, i.e. if stratification effects are negligible. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.725995 [article] A family of explicit algebraic models for reynolds stresses and passive scalar fluxes [texte imprimé] / Martin Ferrand, Auteur ; Violeau, Damien, Auteur . - 2012 . - pp. 494-505. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 494-505 Mots-clés : Explicit  algebraic  model  Passive  scalar  Reynolds  stress  Turbulence  Turbulent  flux Résumé : A family of explicit algebraic models for Reynolds stresses and passive scalar fluxes is proposed and a few variants are discussed, according to the selected set of model constants. Validation is attempted against direct numerical simulation in a steady closed-channel flow for two values of the Reynolds number, indicating the ability of the model to reasonably predict the anisotropy tensor and the scalar flux components when considering wall functions to account for near-wall effects. The production of turbulent kinetic energy is well predicted, while the neutral turbulent Prandtl number has values in agreement with the literature. The proposed model is then compared with an experiment on a heated cylinder with slight temperature variations, with satisfactory results. The proposed model can be applied to various 2D simply-sheared flows involving a passive scalar, i.e. if stratification effects are negligible. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.725995

Experimental observation and modelling of roughness variation due to supply-limited sediment transport in uni-directional flow / Arjan P. Tuijnder in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 506-520 Titre : Experimental observation and modelling of roughness variation due to supply-limited sediment transport in uni-directional flow Type de document : texte imprimé Auteurs : Arjan P. Tuijnder, Auteur ; Jan S. Ribberink, Auteur Année de publication : 2012 Article en page(s) : pp. 506-520 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bedform  dimensions  Immobile  layer  Riverbed  roughness  Sand  gravel  mixture  Ssupply  limitation Résumé : This paper presents a study on the relationship between supply-limited bedform formation and the hydraulic roughness of the riverbed. The results of several new sets of flume experiments with supply-limited or partial transport conditions with bimodal sediment are presented. The results show that both the bedform and grain-related roughness show a clear dependency on the degree of supply limitation. This variation can be attributed to the reduction of the bedform dimensions with a decreasing availability of mobile sediment and an increasing exposure of the usually coarser sublayer (armour layer or pavement) that causes the supply limitation. In the present study, we present a new method to predict the exposure of the immobile sublayer, as well as the bedform and grain-related roughness under supply-limited conditions. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.719201 [article] Experimental observation and modelling of roughness variation due to supply-limited sediment transport in uni-directional flow [texte imprimé] / Arjan P. Tuijnder, Auteur ; Jan S. Ribberink, Auteur . - 2012 . - pp. 506-520. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 506-520 Mots-clés : Bedform  dimensions  Immobile  layer  Riverbed  roughness  Sand  gravel  mixture  Ssupply  limitation Résumé : This paper presents a study on the relationship between supply-limited bedform formation and the hydraulic roughness of the riverbed. The results of several new sets of flume experiments with supply-limited or partial transport conditions with bimodal sediment are presented. The results show that both the bedform and grain-related roughness show a clear dependency on the degree of supply limitation. This variation can be attributed to the reduction of the bedform dimensions with a decreasing availability of mobile sediment and an increasing exposure of the usually coarser sublayer (armour layer or pavement) that causes the supply limitation. In the present study, we present a new method to predict the exposure of the immobile sublayer, as well as the bedform and grain-related roughness under supply-limited conditions. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.719201

Predicting oxygen transfer efficiency at low-head gated sill structures / Adam M. Witt in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 521-531 Titre : Predicting oxygen transfer efficiency at low-head gated sill structures Type de document : texte imprimé Auteurs : Adam M. Witt, Auteur ; John S. Gulliver, Auteur Année de publication : 2012 Article en page(s) : pp. 521-531 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Aerated  flows  Air–water  interface  interactions  Bubble  dynamics  Flow–structure  interactions  Gas  transfer  Hydraulic  jump  Water  quality Résumé : An improved model for predicting oxygen transfer efficiency at gated sills is presented. An analysis of field measurements from eight gated sill structures is used to develop a dimensionless relationship between inflow conditions, dam geometry and oxygen transfer efficiency. The oxygen transfer coefficient is estimated from scaled formulations of the liquid film coefficient, mean bubble diameter, air entrainment rate and turbulent energy dissipation rate. The model is validated with additional field measurements adjusted for temperature and effective saturation concentration. A design parameter for gated sill dams is introduced giving a relationship between gate opening and oxygen transfer efficiency. Improved prediction of oxygen transfer in the field is a tool that can be used to successfully operate gated structures to meet oxygen concentration requirements and to assist in the design of remediation technologies. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.729163 [article] Predicting oxygen transfer efficiency at low-head gated sill structures [texte imprimé] / Adam M. Witt, Auteur ; John S. Gulliver, Auteur . - 2012 . - pp. 521-531. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 521-531 Mots-clés : Aerated  flows  Air–water  interface  interactions  Bubble  dynamics  Flow–structure  interactions  Gas  transfer  Hydraulic  jump  Water  quality Résumé : An improved model for predicting oxygen transfer efficiency at gated sills is presented. An analysis of field measurements from eight gated sill structures is used to develop a dimensionless relationship between inflow conditions, dam geometry and oxygen transfer efficiency. The oxygen transfer coefficient is estimated from scaled formulations of the liquid film coefficient, mean bubble diameter, air entrainment rate and turbulent energy dissipation rate. The model is validated with additional field measurements adjusted for temperature and effective saturation concentration. A design parameter for gated sill dams is introduced giving a relationship between gate opening and oxygen transfer efficiency. Improved prediction of oxygen transfer in the field is a tool that can be used to successfully operate gated structures to meet oxygen concentration requirements and to assist in the design of remediation technologies. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.729163

Effect of air release height on the formation of sediment thermals in water / Bing Zhao in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 532-540 Titre : Effect of air release height on the formation of sediment thermals in water Type de document : texte imprimé Auteurs : Bing Zhao, Auteur ; Adrian W.K. Law, Auteur ; Adams, E. Eric, Auteur Année de publication : 2012 Article en page(s) : pp. 532-540 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Dredged  material  Miscible  thermal  Particle  cloud  Sediment  disposal  Virtual  origin Résumé : In this study, the underwater behaviour of sediment thermals (i.e. sediment clouds in the self-preserving phase), formed by releasing dry sediments instantaneously from various heights above water, was investigated experimentally. Measurements show that as the air release height increases, the initial acceleration phase of the sediment cloud in water is shortened, while the growth rate during its self-preserving phase remains constant. Therefore, the effect of air release height can be accounted for by utilizing a new concept of simultaneous virtual distance and time origins, which are found to be related to an impact densimetric Froude number (defined as the ratio between the impact velocity of the sediment cluster at the water surface and the characteristic velocity of the sediment thermal generated by buoyancy excess). Based on the measurement results, a semi-empirical model is utilized to predict the growth and penetration behaviours of the sediment thermal. Predictions by the model with the virtual origins correction match well with the experimental data. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.715094 [article] Effect of air release height on the formation of sediment thermals in water [texte imprimé] / Bing Zhao, Auteur ; Adrian W.K. Law, Auteur ; Adams, E. Eric, Auteur . - 2012 . - pp. 532-540. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 532-540 Mots-clés : Dredged  material  Miscible  thermal  Particle  cloud  Sediment  disposal  Virtual  origin Résumé : In this study, the underwater behaviour of sediment thermals (i.e. sediment clouds in the self-preserving phase), formed by releasing dry sediments instantaneously from various heights above water, was investigated experimentally. Measurements show that as the air release height increases, the initial acceleration phase of the sediment cloud in water is shortened, while the growth rate during its self-preserving phase remains constant. Therefore, the effect of air release height can be accounted for by utilizing a new concept of simultaneous virtual distance and time origins, which are found to be related to an impact densimetric Froude number (defined as the ratio between the impact velocity of the sediment cluster at the water surface and the characteristic velocity of the sediment thermal generated by buoyancy excess). Based on the measurement results, a semi-empirical model is utilized to predict the growth and penetration behaviours of the sediment thermal. Predictions by the model with the virtual origins correction match well with the experimental data. ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.715094

Regions of bars, meandering and braiding in da Silva and Yalin's plan / Kourosh Babaeyan-Koopaei in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 541-542 Titre : Regions of bars, meandering and braiding in da Silva and Yalin's plan Type de document : texte imprimé Auteurs : Kourosh Babaeyan-Koopaei, Auteur Année de publication : 2012 Article en page(s) : pp. 541-542 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : Discussion ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.716579 [article] Regions of bars, meandering and braiding in da Silva and Yalin's plan [texte imprimé] / Kourosh Babaeyan-Koopaei, Auteur . - 2012 . - pp. 541-542. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 541-542 Note de contenu : Discussion ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.716579

Regions of bars, meandering and braiding in da Silva and Yalin's plan / Habib Ahmari in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 542-543 Titre : Regions of bars, meandering and braiding in da Silva and Yalin's plan Type de document : texte imprimé Auteurs : Habib Ahmari, Auteur ; Ana Maria Ferreira Da Silva, Auteur Année de publication : 2012 Article en page(s) : pp. 542-543 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : Discussion ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.716582 [article] Regions of bars, meandering and braiding in da Silva and Yalin's plan [texte imprimé] / Habib Ahmari, Auteur ; Ana Maria Ferreira Da Silva, Auteur . - 2012 . - pp. 542-543. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 542-543 Note de contenu : Discussion ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.716582

A 2D shallow flow model for practical dam-break simulation / Joe Sampson in Journal of hydraulic research, Vol. 50 N° 5 (Septembre/Octobre 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 544-545 Titre : A 2D shallow flow model for practical dam-break simulation Type de document : texte imprimé Auteurs : Joe Sampson, Auteur Année de publication : 2012 Article en page(s) : pp. 544-545 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : Discussion ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.727873 [article] A 2D shallow flow model for practical dam-break simulation [texte imprimé] / Joe Sampson, Auteur . - 2012 . - pp. 544-545. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 5 (Septembre/Octobre 2012) . - pp. 544-545 Note de contenu : Discussion ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.727873

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