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Ajouter le résultat dans votre panierSource term treatment of SWEs using surface gradient upwind method / Jaan Hui Pu in Journal of hydraulic research, Vol. 50 N° 2 (Mars/Avril 2012)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 145-153
Titre : Source term treatment of SWEs using surface gradient upwind method Type de document : texte imprimé Auteurs : Jaan Hui Pu, Auteur ; Cheng, Nian-Sheng, Auteur ; Keat Tan, Soon, Auteur Année de publication : 2012 Article en page(s) : pp. 145-153 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Finite volume model Harten–Lax–van Leer-contact solver Monotonic upwind scheme Source term Surface gradient upwind method Well-balanced scheme Résumé : Owing to unpredictable bed topography conditions in natural shallow flows, various numerical methods have been developed to improve the treatment of source terms in the shallow water equations. The surface gradient method is an attractive approach as it includes a numerically simple approach to model flows over topographically-varied channels. To further improve the performance of this method, this study deals with the numerical improvement of the shallow-flow source terms. The so-called surface gradient upwind method (SGUM) integrates the source term treatment in the inviscid discretization scheme. A finite volume model (FVM) with the monotonic upwind scheme for conservative laws is used. The Harten–Lax–van Leer-contact approximate Riemann solver is used to reconstruct the Riemann problem in the FVM. The proposed method is validated against published analytical, numerical, and experimental data, indicating that the SGUM is robust and treats the source terms in different flow conditions well. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.649838 [article] Source term treatment of SWEs using surface gradient upwind method [texte imprimé] / Jaan Hui Pu, Auteur ; Cheng, Nian-Sheng, Auteur ; Keat Tan, Soon, Auteur . - 2012 . - pp. 145-153.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 145-153
Mots-clés : Finite volume model Harten–Lax–van Leer-contact solver Monotonic upwind scheme Source term Surface gradient upwind method Well-balanced scheme Résumé : Owing to unpredictable bed topography conditions in natural shallow flows, various numerical methods have been developed to improve the treatment of source terms in the shallow water equations. The surface gradient method is an attractive approach as it includes a numerically simple approach to model flows over topographically-varied channels. To further improve the performance of this method, this study deals with the numerical improvement of the shallow-flow source terms. The so-called surface gradient upwind method (SGUM) integrates the source term treatment in the inviscid discretization scheme. A finite volume model (FVM) with the monotonic upwind scheme for conservative laws is used. The Harten–Lax–van Leer-contact approximate Riemann solver is used to reconstruct the Riemann problem in the FVM. The proposed method is validated against published analytical, numerical, and experimental data, indicating that the SGUM is robust and treats the source terms in different flow conditions well. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.649838
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 154-163
Titre : Finite volumes for 2D shallow-water flow with bed-load transport on unstructured grids Type de document : texte imprimé Auteurs : Alberto Serrano-Pacheco, Auteur ; Javier Murillo, Auteur ; Garcia-Navarro, Pilar, Auteur Année de publication : 2012 Article en page(s) : pp. 154-163 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bed-load transport Exner equation Grass model Shallow-water system Unstructured grid Résumé : In this work, two-dimensional (2D) bed-load transport simulations based on the depth-averaged shallow-water equations and the Exner equation are presented. The Exner equation is written assuming that bed-load transport is governed by a power law of the depth-averaged flow velocity and by a flow/sediment interaction parameter acting as a calibration coefficient. Uncoupled and coupled numerical resolutions of the global problem are considered. A Roe-type first-order upwind scheme has been applied as approximate Riemann solver for the discretization on 2D unstructured meshes. The uncoupled resolution is presented as a simple extension of a previous 2D shallow-water model. The details of the new implementation in the coupled system problem are provided. The models are tested comparing with exact solutions of 2D cases as well as experimental laboratory data. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.669142 [article] Finite volumes for 2D shallow-water flow with bed-load transport on unstructured grids [texte imprimé] / Alberto Serrano-Pacheco, Auteur ; Javier Murillo, Auteur ; Garcia-Navarro, Pilar, Auteur . - 2012 . - pp. 154-163.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 154-163
Mots-clés : Bed-load transport Exner equation Grass model Shallow-water system Unstructured grid Résumé : In this work, two-dimensional (2D) bed-load transport simulations based on the depth-averaged shallow-water equations and the Exner equation are presented. The Exner equation is written assuming that bed-load transport is governed by a power law of the depth-averaged flow velocity and by a flow/sediment interaction parameter acting as a calibration coefficient. Uncoupled and coupled numerical resolutions of the global problem are considered. A Roe-type first-order upwind scheme has been applied as approximate Riemann solver for the discretization on 2D unstructured meshes. The uncoupled resolution is presented as a simple extension of a previous 2D shallow-water model. The details of the new implementation in the coupled system problem are provided. The models are tested comparing with exact solutions of 2D cases as well as experimental laboratory data. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.669142
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 164-170
Titre : Comparative study of 1D and 2D flow simulations at open-channel junctions Type de document : texte imprimé Auteurs : Ghostine, Rabih, Auteur ; Vazquez, José, Auteur ; Terfous, Abdelali, Auteur Année de publication : 2012 Article en page(s) : pp. 164-170 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Combining model Discontinuous galerkin method Numerical modelling Open-channel junction Saint-Venant equations Steady flow Résumé : In this paper, a comparison between the 1D and 2D approaches for simulating combining flows at open-channel junctions is presented. The two approaches are described allowing for a full comprehension of flow modelling. For flows in an open-channel network, mutual effects exist among the channel branches at a junction. Therefore, the 1D Saint-Venant equations for the branch flows are supplemented by various junction models. The existing models are of empirical nature and depend on the flow regime and thus are not practical in all cases. The numerical approximation of the two approaches is performed by the Runge–Kutta discontinuous Galerkin scheme and tested using defined flow problems to illustrate the results of the two approaches. Comparisons are conducted for supercritical, transitional and subcritical flows, indicating the validity range of the 1D approach and the advantages of the 2D approach. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.661563 [article] Comparative study of 1D and 2D flow simulations at open-channel junctions [texte imprimé] / Ghostine, Rabih, Auteur ; Vazquez, José, Auteur ; Terfous, Abdelali, Auteur . - 2012 . - pp. 164-170.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 164-170
Mots-clés : Combining model Discontinuous galerkin method Numerical modelling Open-channel junction Saint-Venant equations Steady flow Résumé : In this paper, a comparison between the 1D and 2D approaches for simulating combining flows at open-channel junctions is presented. The two approaches are described allowing for a full comprehension of flow modelling. For flows in an open-channel network, mutual effects exist among the channel branches at a junction. Therefore, the 1D Saint-Venant equations for the branch flows are supplemented by various junction models. The existing models are of empirical nature and depend on the flow regime and thus are not practical in all cases. The numerical approximation of the two approaches is performed by the Runge–Kutta discontinuous Galerkin scheme and tested using defined flow problems to illustrate the results of the two approaches. Comparisons are conducted for supercritical, transitional and subcritical flows, indicating the validity range of the 1D approach and the advantages of the 2D approach. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.661563
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 171-180
Titre : Local scour at bridge abutments in cohesive soil Type de document : texte imprimé Auteurs : Mokhles M. Abou-Seida, Auteur ; Gamal H. Elsaeed, Auteur ; Tarek M. Mostafa, Auteur Année de publication : 2012 Article en page(s) : pp. 171-180 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bridge abutment Cohesive soil Experimentation Open channel flow Scour Résumé : The results of a laboratory investigation on local scour at bridge abutments in cohesive soils are presented. Kaolin clay was used as a bed material and vertical wall abutments with three different sizes. Forty experiments were conducted under clear-water conditions in cohesive soil with a clay content ranging from 2 to 20%, compaction ranges from 57 to 88%, liquidity index ranges from 0.03 to 0.99 and the approach flow Froude numbers from 0.3 to 0.55. Equations were developed to predict the equilibrium scour pattern around the vertical bridge abutment, including the maximum scour depth, scour volume, scour width, lateral side slope, and longitudinal slopes of the scour hole, in terms of the dominating factors controlling the scour process, namely the Froude number, clay content, compaction, water content, liquid limit, plastic limit, and vertical-wall abutments dimensions. Also, an equation was developed to predict the development of scour depth with time. Comparisons with previous results are also discussed. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.654668 [article] Local scour at bridge abutments in cohesive soil [texte imprimé] / Mokhles M. Abou-Seida, Auteur ; Gamal H. Elsaeed, Auteur ; Tarek M. Mostafa, Auteur . - 2012 . - pp. 171-180.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 171-180
Mots-clés : Bridge abutment Cohesive soil Experimentation Open channel flow Scour Résumé : The results of a laboratory investigation on local scour at bridge abutments in cohesive soils are presented. Kaolin clay was used as a bed material and vertical wall abutments with three different sizes. Forty experiments were conducted under clear-water conditions in cohesive soil with a clay content ranging from 2 to 20%, compaction ranges from 57 to 88%, liquidity index ranges from 0.03 to 0.99 and the approach flow Froude numbers from 0.3 to 0.55. Equations were developed to predict the equilibrium scour pattern around the vertical bridge abutment, including the maximum scour depth, scour volume, scour width, lateral side slope, and longitudinal slopes of the scour hole, in terms of the dominating factors controlling the scour process, namely the Froude number, clay content, compaction, water content, liquid limit, plastic limit, and vertical-wall abutments dimensions. Also, an equation was developed to predict the development of scour depth with time. Comparisons with previous results are also discussed. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.654668
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 181-191
Titre : Deflector-jets affected by pre-aerated approach flow Type de document : texte imprimé Auteurs : Michael Pfister, Auteur ; Willi H. Hager, Auteur Année de publication : 2012 Article en page(s) : pp. 181-191 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Air concentration Chute Deflector Jet Pre-aeration Trajectory Résumé : Jets generated at chute ends move a potential scour zone away from the dam, and dissipate flow energy to reduce the scour. Usually, so-called flip buckets or ski jumps are provided to generate jets, yet they are rarely issued by deflectors. The application of a theoretical mass point parabola is limited to predict the jet features, because effects related to the take-off angle and the disintegration process affect the jet air transport and trajectories. This research discusses the effect of pre-aeration of the approach chute flow on the jet features. A comparison with a former study indicates that mainly the upper jet portion is affected, that the black water jet core becomes shorter, and that the air transport increases. Although the lower trajectory is less affected and thus remains more coherent, the small effect of pre-aeration is sufficient to reduce the total jet throw length, so that pre-aerated jets tend to be shorter as compared with black-water approach flow jets, in agreement with prototype observations. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.657875 [article] Deflector-jets affected by pre-aerated approach flow [texte imprimé] / Michael Pfister, Auteur ; Willi H. Hager, Auteur . - 2012 . - pp. 181-191.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 181-191
Mots-clés : Air concentration Chute Deflector Jet Pre-aeration Trajectory Résumé : Jets generated at chute ends move a potential scour zone away from the dam, and dissipate flow energy to reduce the scour. Usually, so-called flip buckets or ski jumps are provided to generate jets, yet they are rarely issued by deflectors. The application of a theoretical mass point parabola is limited to predict the jet features, because effects related to the take-off angle and the disintegration process affect the jet air transport and trajectories. This research discusses the effect of pre-aeration of the approach chute flow on the jet features. A comparison with a former study indicates that mainly the upper jet portion is affected, that the black water jet core becomes shorter, and that the air transport increases. Although the lower trajectory is less affected and thus remains more coherent, the small effect of pre-aeration is sufficient to reduce the total jet throw length, so that pre-aerated jets tend to be shorter as compared with black-water approach flow jets, in agreement with prototype observations. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.657875
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 192-199
Titre : Energy dissipation and flow characteristics of baffles and sills on stepped spillways Type de document : texte imprimé Auteurs : Hesham K. Zare, Auteur ; John C. Doering, Auteur Année de publication : 2012 Article en page(s) : pp. 192-199 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Baffle-stepped spillway Cavity End-sill spillway Energy dissipation Flow characteristics Rounded-stepped spillway Sharp-stepped spillway Skimming flow Résumé : In this study, a two-dimensional physical model was used to evaluate the effectiveness of adding baffles and sills at step edges or of shifting them from step edges of a 1V:1H sloping, short, sharp- or round-crested stepped spillway with an ogee inlet. A comparison between different configurations of baffles and sills was carried out with respect to the energy dissipation and the flow characteristics. The baffle-shifted round-crested spillway gives the smallest discharge required for the onset of a skimming flow among all other configurations. The baffle-edged chute dissipates more energy than the sill-edged spillway. Shifting baffles or sills from the sharp edges decreases the energy dissipation. Shifting baffles or sills from the round-crested spillway increases the energy dissipation in the range of the discharges studied. Empirical equations for energy dissipation are introduced for practical application of spillways of comparable similar conditions. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.659840 [article] Energy dissipation and flow characteristics of baffles and sills on stepped spillways [texte imprimé] / Hesham K. Zare, Auteur ; John C. Doering, Auteur . - 2012 . - pp. 192-199.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 192-199
Mots-clés : Baffle-stepped spillway Cavity End-sill spillway Energy dissipation Flow characteristics Rounded-stepped spillway Sharp-stepped spillway Skimming flow Résumé : In this study, a two-dimensional physical model was used to evaluate the effectiveness of adding baffles and sills at step edges or of shifting them from step edges of a 1V:1H sloping, short, sharp- or round-crested stepped spillway with an ogee inlet. A comparison between different configurations of baffles and sills was carried out with respect to the energy dissipation and the flow characteristics. The baffle-shifted round-crested spillway gives the smallest discharge required for the onset of a skimming flow among all other configurations. The baffle-edged chute dissipates more energy than the sill-edged spillway. Shifting baffles or sills from the sharp edges decreases the energy dissipation. Shifting baffles or sills from the round-crested spillway increases the energy dissipation in the range of the discharges studied. Empirical equations for energy dissipation are introduced for practical application of spillways of comparable similar conditions. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.659840
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 200-207
Titre : Temporal variation of vortex scour process around caisson piers Type de document : texte imprimé Auteurs : Gangarudraiah Veerappadevaru, Auteur ; Thimmaiah Gangadharaiah, Auteur ; Thirumalai Ramaswamyiyenger Jagadeesh, Auteur Année de publication : 2012 Article en page(s) : pp. 200-207 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Bridge pier Caisson Power concept River engineering Scour Vortex Résumé : The concept of conservation of power during scour by the primary vortex formed in front of caisson piers is used to develop a relation for the temporal of scour depth variation. To test this relation, experiments were conducted using two sediment beds, three types of caisson piers and four relative flow depths. The agreement between the temporal variation of scour depths from the present approach and the literature data is good. The computed values of other researchers also agree fairly with the present proportionality constants. An expression for scour duration to reach the equilibrium scour depth is deduced from the power concept based on long duration literature data. The validity of this expression is verified for the equilibrium duration concept. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.666832 [article] Temporal variation of vortex scour process around caisson piers [texte imprimé] / Gangarudraiah Veerappadevaru, Auteur ; Thimmaiah Gangadharaiah, Auteur ; Thirumalai Ramaswamyiyenger Jagadeesh, Auteur . - 2012 . - pp. 200-207.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 200-207
Mots-clés : Bridge pier Caisson Power concept River engineering Scour Vortex Résumé : The concept of conservation of power during scour by the primary vortex formed in front of caisson piers is used to develop a relation for the temporal of scour depth variation. To test this relation, experiments were conducted using two sediment beds, three types of caisson piers and four relative flow depths. The agreement between the temporal variation of scour depths from the present approach and the literature data is good. The computed values of other researchers also agree fairly with the present proportionality constants. An expression for scour duration to reach the equilibrium scour depth is deduced from the power concept based on long duration literature data. The validity of this expression is verified for the equilibrium duration concept. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.666832
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 208-217
Titre : A two-layer, shallow-water model for 3D gravity currents Type de document : texte imprimé Auteurs : Michele La Rocca, Auteur ; Adduce, Claudia, Auteur ; Giampiero Sciortino, Auteur Année de publication : 2012 Article en page(s) : pp. 208-217 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Gravity current Hyperbolic partial differential equation Shallow-water equations Stratified fluid Résumé : A two-layer, shallow-water model for three-dimensional (3D) gravity currents is proposed. The formulation results from the shallow-water-equations for two layers of immiscible liquids, subjected by the rigid-lid condition, so that the upper surface of the lighter layer remains perfectly flat during the motion. The arising pressure must be determined by solving the equations of motion, which is no problem for two-dimensional and axisymmetric gravity currents because the pressure is easily eliminated. In 3D gravity currents, the pressure is determined by solving a Poisson equation, together with momentum and mass balance equations. By means of a suitable scaling and a perturbation expansion, the equations are uncoupled from each other so that the problem is considerably simplified. Numerical results are compared with 3D lock-exchange release experiments. A comparison between numerical and experimental results of the gravity current indicates a fairly good agreement, whereas the results concerning the upper layer field variables shows that the numerical results are consistent with the experiments. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.667680 [article] A two-layer, shallow-water model for 3D gravity currents [texte imprimé] / Michele La Rocca, Auteur ; Adduce, Claudia, Auteur ; Giampiero Sciortino, Auteur . - 2012 . - pp. 208-217.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 208-217
Mots-clés : Gravity current Hyperbolic partial differential equation Shallow-water equations Stratified fluid Résumé : A two-layer, shallow-water model for three-dimensional (3D) gravity currents is proposed. The formulation results from the shallow-water-equations for two layers of immiscible liquids, subjected by the rigid-lid condition, so that the upper surface of the lighter layer remains perfectly flat during the motion. The arising pressure must be determined by solving the equations of motion, which is no problem for two-dimensional and axisymmetric gravity currents because the pressure is easily eliminated. In 3D gravity currents, the pressure is determined by solving a Poisson equation, together with momentum and mass balance equations. By means of a suitable scaling and a perturbation expansion, the equations are uncoupled from each other so that the problem is considerably simplified. Numerical results are compared with 3D lock-exchange release experiments. A comparison between numerical and experimental results of the gravity current indicates a fairly good agreement, whereas the results concerning the upper layer field variables shows that the numerical results are consistent with the experiments. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.667680
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 218-227
Titre : Effect of drop in pipe wall stiffness on water-hammer speed and attenuation Type de document : texte imprimé Auteurs : Fadi E. Hachem, Auteur ; Anton J. Schleiss, Auteur Année de publication : 2012 Article en page(s) : pp. 218-227 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Geophone Monitoring Steel-lined tunnel Wall stiffness Water-hammer Wave attenuation Wave speed Résumé : The effect of local drop of wall stiffness in pressurized waterways on the pressure wave speed and the wave attenuation during transients is investigated experimentally. A new signal-processing procedure to identify the presence of a weak reach is introduced and validated by physical experimentation based on assessing the pressure and vibration records acquired at both ends of a multi-reach steel test pipe. Water-hammer was generated by closing a downstream valve, whereas the weak reaches were simulated by replacing the steel portions with aluminium and PVC material. The wave speed and wave attenuation factor during transients are considered as global indicators of local and large changes in stiffness of the pipe wall. The method is capable of locating the stiffness weakness along the test pipe if one PVC reach is used. The error in estimating the position of such a reach relative to the real position of its mean value varies up to 23%. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.656838 [article] Effect of drop in pipe wall stiffness on water-hammer speed and attenuation [texte imprimé] / Fadi E. Hachem, Auteur ; Anton J. Schleiss, Auteur . - 2012 . - pp. 218-227.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 218-227
Mots-clés : Geophone Monitoring Steel-lined tunnel Wall stiffness Water-hammer Wave attenuation Wave speed Résumé : The effect of local drop of wall stiffness in pressurized waterways on the pressure wave speed and the wave attenuation during transients is investigated experimentally. A new signal-processing procedure to identify the presence of a weak reach is introduced and validated by physical experimentation based on assessing the pressure and vibration records acquired at both ends of a multi-reach steel test pipe. Water-hammer was generated by closing a downstream valve, whereas the weak reaches were simulated by replacing the steel portions with aluminium and PVC material. The wave speed and wave attenuation factor during transients are considered as global indicators of local and large changes in stiffness of the pipe wall. The method is capable of locating the stiffness weakness along the test pipe if one PVC reach is used. The error in estimating the position of such a reach relative to the real position of its mean value varies up to 23%. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.656838
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 228-235
Titre : Transient vaporous cavitation in viscoelastic pipes Type de document : texte imprimé Auteurs : Alexandre K. Soares, Auteur ; Dídia I.C. Covas, Auteur ; Nelson J.G. Carriço, Auteur Année de publication : 2012 Article en page(s) : pp. 228-235 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Cavitation Fluid transient Polyethylene pipe Viscoelasticity Water hammer Résumé : The research focuses on the analysis of transient cavitating flow in polyethylene pipes, which are characterized by a viscoelastic–rheological behaviour. A hydraulic transient solver incorporating the description of the rheological–mechanical behaviour of these pipes and the cavitating pipe flow has been developed. Both the discrete vapour cavity model and the discrete gas cavity model have been used to describe transient cavitating flow. These assume that discrete air cavities are formed at fixed pipe sections and consider a constant wave speed in the pipe reaches between the cavities. An experimental programme was conducted in a pipe-rig composed of a high-density polyethylene (HDPE) pipeline. Numerical results have been compared with collected data resulting in a good agreement. Effects related to the viscoelasticity of HDPE pipes and to the occurrence of vapour pressures during the transient events are also discussed. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.669143 [article] Transient vaporous cavitation in viscoelastic pipes [texte imprimé] / Alexandre K. Soares, Auteur ; Dídia I.C. Covas, Auteur ; Nelson J.G. Carriço, Auteur . - 2012 . - pp. 228-235.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 228-235
Mots-clés : Cavitation Fluid transient Polyethylene pipe Viscoelasticity Water hammer Résumé : The research focuses on the analysis of transient cavitating flow in polyethylene pipes, which are characterized by a viscoelastic–rheological behaviour. A hydraulic transient solver incorporating the description of the rheological–mechanical behaviour of these pipes and the cavitating pipe flow has been developed. Both the discrete vapour cavity model and the discrete gas cavity model have been used to describe transient cavitating flow. These assume that discrete air cavities are formed at fixed pipe sections and consider a constant wave speed in the pipe reaches between the cavities. An experimental programme was conducted in a pipe-rig composed of a high-density polyethylene (HDPE) pipeline. Numerical results have been compared with collected data resulting in a good agreement. Effects related to the viscoelasticity of HDPE pipes and to the occurrence of vapour pressures during the transient events are also discussed. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.669143
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 236-240
Titre : Experimental study on time-averaged pressures in stepped spillway Type de document : texte imprimé Auteurs : Jianmin Zhang, Auteur ; Jiangang Chen, Auteur ; Yurong Wang, Auteur Année de publication : 2012 Article en page(s) : pp. 236-240 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Experimentation Flow pattern Non-aerated flow Pressure characteristic Stepped spillway Résumé : Steps located in the non-aerated flow region of a chute are prone to cavitation damage. Two models operated with various Froude numbers and bottom slopes were employed to measure the pressure on the steps. The minimum and maximum pressures on the horizontal step surfaces occurred at the chute beginning and at the chute end, respectively. These characteristics were also found in the fully-developed flow region. The time-averaged pressure on the horizontal step surfaces is negative at the chute start, and then becomes positive along the flow direction in the non-uniform flow region. On the vertical step surfaces, the pressure is always negative at the top and remains negative along the entire vertical surface if the unit discharges are high enough in the non-uniform flow region. These results differ from the pressure characteristics in the uniform aerated flow region. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.666879 [article] Experimental study on time-averaged pressures in stepped spillway [texte imprimé] / Jianmin Zhang, Auteur ; Jiangang Chen, Auteur ; Yurong Wang, Auteur . - 2012 . - pp. 236-240.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 236-240
Mots-clés : Experimentation Flow pattern Non-aerated flow Pressure characteristic Stepped spillway Résumé : Steps located in the non-aerated flow region of a chute are prone to cavitation damage. Two models operated with various Froude numbers and bottom slopes were employed to measure the pressure on the steps. The minimum and maximum pressures on the horizontal step surfaces occurred at the chute beginning and at the chute end, respectively. These characteristics were also found in the fully-developed flow region. The time-averaged pressure on the horizontal step surfaces is negative at the chute start, and then becomes positive along the flow direction in the non-uniform flow region. On the vertical step surfaces, the pressure is always negative at the top and remains negative along the entire vertical surface if the unit discharges are high enough in the non-uniform flow region. These results differ from the pressure characteristics in the uniform aerated flow region. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.666879
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 241-243
Titre : Overflow characteristics of circular-crested weirs Type de document : texte imprimé Auteurs : Oscar Castro-Orgaz, Auteur Année de publication : 2012 Article en page(s) : pp. 241-243 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : By SARA BAGHERI and MANOUCHEHR HEIDARPOUR, Journal of Hydraulic Research, Vol. 48, No. 4 (2010), pp. 515–520 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.641818 [article] Overflow characteristics of circular-crested weirs [texte imprimé] / Oscar Castro-Orgaz, Auteur . - 2012 . - pp. 241-243.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 241-243
Note de contenu : By SARA BAGHERI and MANOUCHEHR HEIDARPOUR, Journal of Hydraulic Research, Vol. 48, No. 4 (2010), pp. 515–520 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2011.641818
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 244-246
Titre : Scale effects in physical hydraulic engineering models Type de document : texte imprimé Auteurs : Michael Pfister, Auteur ; Chanson, Hubert, Auteur Année de publication : 2012 Article en page(s) : pp. 244-246 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : By VALENTIN HELLER, Journal of Hydraulic Research, Vol. 49, No. 3 (2011), pp. 293–306 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.654671 [article] Scale effects in physical hydraulic engineering models [texte imprimé] / Michael Pfister, Auteur ; Chanson, Hubert, Auteur . - 2012 . - pp. 244-246.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 244-246
Note de contenu : By VALENTIN HELLER, Journal of Hydraulic Research, Vol. 49, No. 3 (2011), pp. 293–306 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.654671
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 247-248
Titre : Scale effects in physical hydraulic engineering models Type de document : texte imprimé Auteurs : Ali Tafarojnoruz, Auteur ; Roberto Gaudio, Auteur Année de publication : 2012 Article en page(s) : pp. 247-248 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : By VALENTIN HELLER, Journal of Hydraulic Research, Vol. 49, No. 3 (2011), pp. 293–306 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.668377 [article] Scale effects in physical hydraulic engineering models [texte imprimé] / Ali Tafarojnoruz, Auteur ; Roberto Gaudio, Auteur . - 2012 . - pp. 247-248.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 247-248
Note de contenu : By VALENTIN HELLER, Journal of Hydraulic Research, Vol. 49, No. 3 (2011), pp. 293–306 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.668377
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 249-250
Titre : Scale effects in physical hydraulic engineering models Type de document : texte imprimé Auteurs : Gabriel Echávez, Auteur Année de publication : 2012 Article en page(s) : pp. 249-250 Note générale : Hydraulique Langues : Anglais (eng) DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.668380 [article] Scale effects in physical hydraulic engineering models [texte imprimé] / Gabriel Echávez, Auteur . - 2012 . - pp. 249-250.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 249-250
DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.668380
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 251-252
Titre : Particle–particle collisions in the Lagrangian modelling of saltating grains Type de document : texte imprimé Auteurs : Nikolay Lukerchenko, Auteur Année de publication : 2012 Article en page(s) : pp. 251-252 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : By ROBERT J. BIALIK, Journal of Hydraulic Research, Vol. 49, No. 1 (2011), pp. 23–31 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.668374 [article] Particle–particle collisions in the Lagrangian modelling of saltating grains [texte imprimé] / Nikolay Lukerchenko, Auteur . - 2012 . - pp. 251-252.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 251-252
Note de contenu : By ROBERT J. BIALIK, Journal of Hydraulic Research, Vol. 49, No. 1 (2011), pp. 23–31 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.668374
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 253-254
Titre : Wave–current interaction at an angle 2: theory Type de document : texte imprimé Auteurs : Peter Nielsen, Auteur Année de publication : 2012 Article en page(s) : pp. 253-254 Note générale : Hydraulique Langues : Anglais (eng) Note de contenu : By PRADEEP C. FERNANDO, PENGZHI LIN and JUNKE GUO, Journal of Hydraulic Research, Vol. 49, No. 4 (2011), pp. 437–449 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00207179.2012.667213 [article] Wave–current interaction at an angle 2: theory [texte imprimé] / Peter Nielsen, Auteur . - 2012 . - pp. 253-254.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 253-254
Note de contenu : By PRADEEP C. FERNANDO, PENGZHI LIN and JUNKE GUO, Journal of Hydraulic Research, Vol. 49, No. 4 (2011), pp. 437–449 DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00207179.2012.667213
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