References of "Dewals, Benjamin"
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See detailPhysical and numerical modelling in low-head structures design
Dewals, Benjamin ULg; Archambeau, Pierre ULg; Rulot, François ULg et al

in Bung, Daniel; Pagliara, Stefano (Eds.) Proceedings of the International Workshop on Hydraulic Design of Low-Head Structures (2013, February)

Physical and numerical modelling may be combined within so-called composite or hybrid modelling. This enables to optimally take benefit of the respective strengths of each modelling approach, while ... [more ▼]

Physical and numerical modelling may be combined within so-called composite or hybrid modelling. This enables to optimally take benefit of the respective strengths of each modelling approach, while compensating for their specific drawbacks. Different types of composite modelling may be identified, such as embedding a detailed physical model within a broader scale numerical model, interconnecting different physical and numerical models focusing each on specific processes, or validating a numerical model from experimental data before exploiting the numerical model to generate more results than availa-ble from the experimental facility. Besides, specifically in more basic research, composite modelling may also be used to improve in-depth understanding of the relative importance of different processes which act simultaneously in the experimental test and may be artificially separated in numerical simulations. [less ▲]

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See detailStepped spillway Downstream of a Piano Key Weir - Critical length for uniform flow
Silvestri, Aurélien ULg; Pirotton, Michel ULg; Erpicum, Sébastien ULg et al

in Bung, Daniel B.; Pagliara, Stefano (Eds.) International Workshop on Hydraulic Design of Low-Head Structures (2013)

Recent researches showed the rapid aeration of the flow downstream of piano key weirs. This could be related to the specific geometric features of the structure, creating several interacting flows and ... [more ▼]

Recent researches showed the rapid aeration of the flow downstream of piano key weirs. This could be related to the specific geometric features of the structure, creating several interacting flows and jets downstream. In order to validate this assumption, an experimental research has been carried out at the Laboratory of Engineering Hydraulics, University of Liège. The main objective of the study was to an-alyze the energy dissipation occurring in skimming flow conditions on a stepped spillway downstream of a piano key weir (PKW). Comparison with energy dissipation on a stepped spillway downstream of a standard ogee crested weir has been performed. An indirect method has been used to determine the resid-ual energy at the spillway toe. The results show that uniform flow conditions are reached faster on a stepped spillway downstream of a PWK compared to the length needed downstream of a standard ogee crested weir. Extrapolation of the results to prototype flow conditions is also discussed with regards to scale effects influence. [less ▲]

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See detailComparative analysis of the energy dissipation on a stepped spillway downstream of a Piano Key Weir
Silvestri, Aurélien ULg; Archambeau, Pierre ULg; Pirotton, Michel ULg et al

in Erpicum, Sébastien; Laugier, Frédéric; Pfister, Michael (Eds.) et al Labyrinth and Piano Key Weirs II - PKW 2013 (2013)

A systematic experimental study has been carried out to compare the residual energy at the toe of a stepped spillway of varied length considering a classical ogee-crested weir (OCW) or two different piano ... [more ▼]

A systematic experimental study has been carried out to compare the residual energy at the toe of a stepped spillway of varied length considering a classical ogee-crested weir (OCW) or two different piano key weirs (PKW) at the top of the structure. Four spillway lengths have been considered on a wide range of discharge. An indirect method has been used to compute the residual flow energy at the spillway toe from water depth measurements in a horizontal channel downstream. The results indicate that uniform flow conditions, i.e. flow energy at the spillway toe independent of the spillway length, are reached on significantly shorter spillways downstream of a PKW than downstream of an OCW. However, the uniform flow energy at constant discharge on the spillway is found to vary depending on the weir type. In particular, it is smaller downstream of the OCW than downstream of the PKWs. [less ▲]

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See detailDike-break induced flows: a simplified model
Stilmant, Frédéric ULg; Pirotton, Michel ULg; Archambeau, Pierre ULg et al

in Environmental Fluid Mechanics (2013), 13(1), 89-100

A simplified model for the prediction of the steady-state outflowthrough a breach in an inland dike is presented. It consists in the application of the mass and momentum conservation principles to a ... [more ▼]

A simplified model for the prediction of the steady-state outflowthrough a breach in an inland dike is presented. It consists in the application of the mass and momentum conservation principles to a macroscopic control volume. A proper definition of the shape of the control volume enables to take the main characteristics of the flow into account and thus to compensate for the extreme simplification of the spatial representation of the model. At the breach, a relation derived from the shallow-water equations is used to determine the direction of the flow. Developments have been guided by numerical simulations and results have been compared to experimental data. Both the accuracy and the domain of validity of the simplified model are found satisfactory. [less ▲]

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See detailTransboundary Water Management in a Changing Climate
Dewals, Benjamin ULg; Fournier, Maïté

Book published by CRC Press (2013)

Most large river basins in the world are transboundary. Experience with such basins emphasizes the urgent need for more efficient transnational water management. This book details recent initiatives ... [more ▼]

Most large river basins in the world are transboundary. Experience with such basins emphasizes the urgent need for more efficient transnational water management. This book details recent initiatives undertaken in the Meuse basin (North-West Europe) to develop a transnational adaptation strategy to deal with the impact of climate change. In the 21st century, floods in the Meuse basin are expected to become more intense and more frequent, while summers will be hotter and drier. The transnational adaptation strategy combines scientific research to fill important gaps in knowledge, innovative natural and structural water retention measures, and enhanced (transnational) crisis management. As a scientific basis for this adaptation strategy, common climate and hydrological scenarios have been developed, as well as more uniform methods for transnational flood risk assessment and mapping. The contributions in Transboundary Water Management in a Changing Climate were presented at the final conference of the European project AMICE (Sedan, France, March 2013). They demonstrate that the development of a vision at the level of the river basin, rather than within the national or regional boundaries, faces many practical challenges but offers unique opportunities for adaptation. Covering a wide range of topics, from the latest advances in climate and hydrological research to practical implementation of adaptation measures and communication issues, Transboundary Water Management in a Changing Climate offers a genuine bridge between research and practice, and also reports on similar developments in other river basins. [less ▲]

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See detailAn analytical approach for Piano Key weir hydraulic design
Machiels, Olivier; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Erpicum, Sébastien; Laugier, Frédéric; Pfister, Michael (Eds.) et al Labyrinth and Piano Key weirs II - PKW 2013 (2013)

A hydraulic design equation for Piano Key Weirs is set up using the results of a large experimental parametric study. Comparison of the analytical formulation with experi-mental data from various physical ... [more ▼]

A hydraulic design equation for Piano Key Weirs is set up using the results of a large experimental parametric study. Comparison of the analytical formulation with experi-mental data from various physical modeling studies, considering idealized as well as real projects Piano Key Weirs configurations, shows a 15% accuracy in unit discharge prediction on a large range of geometric parameters values. Comparison of the proposed formulation to two other recently proposed equations highlights the importance to consider such analytical approaches inside the range of parameter values for which they have been validated. [less ▲]

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See detailEscouloubre Piano Key weir: prototype versus scale models
Erpicum, Sébastien ULg; Silvestri, Aurélien ULg; Dewals, Benjamin ULg et al

in Erpicum, Sébastien; Laugier, Frédéric; Pfister, Michael (Eds.) et al Labyrinth and Piano Key Weirs II - PKW 2013 (2013)

A 1.77 m high piano key weir in operation on the Escouloubre balance basin enabled the observation of real size flows for discharges ranging from 1.2 to 10 m³/s, corresponding to upstream heads ranging ... [more ▼]

A 1.77 m high piano key weir in operation on the Escouloubre balance basin enabled the observation of real size flows for discharges ranging from 1.2 to 10 m³/s, corresponding to upstream heads ranging from 11 to 48 cm. These observations are depicted and compared to the results gained on three physical models of the weir, built and operated considering a Froude similitude and geometric scale factors of, respectively, 1:7, 1:15 and 1:25. The study highlights the scale effects which may affect piano key weirs scale model studies and provides criteria to limit them. In particular, the results analysis shows that the scale models succeed in representing the flow conditions on the weir when the model upstream head is higher than 60 mm, and succeed in predicting the weir discharge capacity when the model upstream head is higher than 30 mm. [less ▲]

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See detailCoupling between flow and sediment deposition in rectangular shallow reservoirs
Camnasio, Erica; Erpicum, Sébastien ULg; Orsi, Enrico et al

in Journal of Hydraulic Research (2013), 51(5), 535-547

Flow velocity and sedimentation patterns were investigated experimentally and numerically in shallow rectangular reservoirs with different asymmetric locations of the inlet and outlet channels. Velocity ... [more ▼]

Flow velocity and sedimentation patterns were investigated experimentally and numerically in shallow rectangular reservoirs with different asymmetric locations of the inlet and outlet channels. Velocity fields were measured in the entire reservoir, both for clear water flow and with suspended sediments. Thickness of sediment deposits were mapped in the whole reservoir by means of a laser light method. In one of the studied geometric configurations, injection of suspended sediments led to a complete change in the observed flow field. Experimental results were compared with numerical simulations performed with the depth-averaged flow model WOLF 2D, using a depth-averaged k-e turbulence model. The simulations lead to accurate predictions of the velocity profiles and the change in flow pattern as a result of sediment deposits was successfully reproduced. [less ▲]

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See detailModélisation hydraulique detaillée d’inondations extrêmes sur un tronçon transnational de la Meuse
Dewals, Benjamin ULg; Archambeau, Pierre ULg; Erpicum, Sébastien ULg et al

in Evènements extrêmes d’inondation : de l’étude de l’aléa à la gestion du risque pour les ouvrages hydrauliques (2013)

Extreme floods of the river Meuse were simulated based on a detailed 2D unsteady hydraulic model. As part of a coordinated transnational modeling program, the study area considered here extends from ... [more ▼]

Extreme floods of the river Meuse were simulated based on a detailed 2D unsteady hydraulic model. As part of a coordinated transnational modeling program, the study area considered here extends from Ampsin (Belgium) to the Belgian-Dutch border. The results of the present simulations are passed as upstream boundary condition to a second hydraulic model simulating the same flood scenarios in the Meuse in the Netherlands. In the simulations discussed here for the Belgian part of the Meuse, high accuracy and high resolution data were used to represent the main riverbed and the urbanized floodplains. The operation of all influencing mobile dams was represented in the model. The considered flood scenarios include the 100-year flood in the present situation (Q100), as well as two more extreme floods: Q100 + 15 % and Q100 + 30 %. These values correspond to return periods of the order of, respectively 300 and 1000 years in the present climate; but, according to a transnational climate change scenario in the Meuse basin, they may also be considered as estimates of the 100-year flood in 2050 and 2100. The computations have shown a very limited damping of the flood wave in the study area, not exceeding approximately 1 % of the peak discharge for Q100 and Q100 + 15 %, and reaching about 3 % for Q100 + 30 %. Compared to Q100, increases in the flood levels for Q100 + 15 % and Q100 + 30 % are, respectively, in the ranges 0.5-0.9 m and 1.0-1.8 m. Comparisons with the results from previous steady simulations revealed discrepancies not exceeding 5 cm for Q100 and Q100 + 15 %, and reaching a maximum of approximately 30 cm for Q100 + 30 %. Hence, from the perspective of the variation in peak discharge and flood levels, the study concludes that running the hydraulic model in steady mode is reasonable; although some differences occur in terms of inundation extents. The 2D unsteady model constitutes also a tool of primary interest, which is readily available to design and evaluate protection measures for flood-prone areas such as in the city of Liege. [less ▲]

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See detailDepth-averaged flow modeling in curvilinear coordinates
Stilmant, Frédéric ULg; Egan, Raphael ULg; Archambeau, Pierre ULg et al

Conference (2013)

A set of depth-averaged equations in curvilinear coordinates is presented. This extension of the standard shallow water equations to curved flows and to jet flows leads to a model which is very versatile ... [more ▼]

A set of depth-averaged equations in curvilinear coordinates is presented. This extension of the standard shallow water equations to curved flows and to jet flows leads to a model which is very versatile. Its applicability and precision is assessed by the computation of a discharge coefficient and the nappe profiles for a sharp crested weir. Results confirm the relevance of the approach. Even if not taken into consideration in the set of equations presented here, a discussion shows that head losses could be included in the model so as to extend its application field to many civil and environmental engineering applications. [less ▲]

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See detailConsiderations about the optimum design of piano key weirs
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Proceedings of Africa 2013 Conference (CD-Rom) (2013)

Piano Key Weirs, a recent innovation in the Labyrinth Weirs geometry, have been studied for years by several research centers and laboratories all over the world. The first prototypes have already been ... [more ▼]

Piano Key Weirs, a recent innovation in the Labyrinth Weirs geometry, have been studied for years by several research centers and laboratories all over the world. The first prototypes have already been built, mainly in France, and others are under construction in Vietnam, Algeria and India. Despite some general design equations have been proposed recently, no optimum geometry has been defined yet. Whatever its geometry, a PKW is more efficient than a standard linear weir of same width. It is also more efficient than a labyrinth weir with the same cycle shape. But the PKW geometry may appear as complex as it involves a large set of parameters. Optimization of the weir design is thus not straightforward. Using the results of a large number of systematic scale model tests carried out to analyse the effect of the main geometric parameters on the PKW discharge capacity, the paper shows how a single optimum design doesn’t exist. This is especially true when economic and technical criteria are considered instead of a single hydraulic performance criteria. Despite this observation, some general rules to design a PKW can be suggested, as well as considerations about the best value of the main ratios defining the structure geometry. The relative influence of these parameters on the PKW efficiency is also highlighted. [less ▲]

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See detailHydraulic studies for the Taoussa project, Mali
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Proceedings of Africa 2013 conference (CD-Rom) (2013)

The Taoussa Project is a component of a large development scheme of the Niger River in the north-eastern part of Mali aiming at reducing desertification and improving socio-economic activity. It is mainly ... [more ▼]

The Taoussa Project is a component of a large development scheme of the Niger River in the north-eastern part of Mali aiming at reducing desertification and improving socio-economic activity. It is mainly made of a rockfill dam with central core around 18 m high and 1,000 m long across the valley of the Niger River, 130 km upstream of the town of Gao in the eastern part of Mali. The dam is equipped with a 25 MW hydroelectric power plant, a lock, a dock and a spillway. The spillway is made of a gated ogee crested weir divided into 10 bays and a downstream stilling basin, with a maximum discharge capacity of 3,100 m³/s. 210 km of high tension overhead cables and a 130 km long road complete the Project. The multipurpose Taoussa dam will enable the sustainable development of the Project area by securing water resources, increasing low-water level discharges downstream, creating a link between road and fluvial transports (dock) and producing electricity. The Ministère de l’Energie, des Mines et de l’Eau du Mali - Autorité pour l’Aménagement de Taoussa -commissioned Coyne et Bellier – Tractebel Engineering in 2006 to perform the detailed studies for the Project. In this framework, the hydraulic studies have been performed by the Laboratory of Engineering Hydraulics (HECE) of the University of Liege. These hydraulic studies, depicted in details in the paper, have been carried out successively by two complementary approaches: a first step realized on the basis of numerical modelling to study the flows at the scale of the reservoir and the river, and a second experimental investigation, using a scale model, to analyse in details the spillway operation conditions. They consider varied problems from large scale flow conditions in the reservoir during the spillway operation and hydrodynamic interactions between the dam, the lock and the hydroelectric power plant to validation and optimization of the hydraulic design and dimensions of the gated spillway and the stilling basin or release conditions downstream of the project structures, including the temporary derivation stage. [less ▲]

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See detailTransboundary hydraulic modelling of extreme floods in the Meuse River
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Pirotton, Michel ULg et al

in The Wise Find Pleasure in Water (2013)

Detailed inundation modelling was conducted along a 100 km long transnational section of the Meuse River (in Belgium and The Netherlands), using very similar models for the whole computation (2D unsteady ... [more ▼]

Detailed inundation modelling was conducted along a 100 km long transnational section of the Meuse River (in Belgium and The Netherlands), using very similar models for the whole computation (2D unsteady models). As a result, damping of the flood waves could be quantified and the possible relevance of using a steady-state approach could be assessed. The new detailed 2D hydraulic simulations have demonstrated that only a very limited damping of the flood waves occurs along the simulated reaches. From the perspective of the variation in peak discharge, the study concludes that running the hydraulic model in steady mode makes perfectly sense. Nonetheless, the steady computations lead to extensive overestimations of the inundated extent and of the stored volume in the floodplains. The 2D unsteady model constitutes also a tool of primary interest, which is readily available to design and evaluate protection measures for flood-prone areas such as in the city of Liege. [less ▲]

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See detailModélisation numérique hydrosédimentaire au service de la gestion durable des sédiments
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

Conference (2012, October)

Le groupe de recherches HECE de l’ULg développe depuis plus de dix ans les systèmes de modélisation hydrosédimentaire WOLF. Intégrant des modules de simulation 1D, 2D-horizontal, 2D-vertical et 3D, il ... [more ▼]

Le groupe de recherches HECE de l’ULg développe depuis plus de dix ans les systèmes de modélisation hydrosédimentaire WOLF. Intégrant des modules de simulation 1D, 2D-horizontal, 2D-vertical et 3D, il permet la modélisation intégrée des diverses phases d’écoulement depuis le ruissellement hydrologique sur les bassins versants jusqu’aux écoulements fluviaux et au voisinage des structures hydrauliques. Deux gammes d’applications récentes du modèle 2D seront présentées : - écoulements de crues et inondations influencés par les dépôts dans les voies navigables et analyse de l’efficacité d’opérations de dragage ; - prédiction de l’engravement de réservoirs (aménagements hydroélectriques) et simulation de mesures de gestion de ces sédiments (opérations de chasse). L’accent sera mis tant sur le volet applicatif que sur les développements numériques innovants sous-jacents. [less ▲]

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See detailFeedback from reservoir sedimentation on the flow pattern in rectangular basins
Camnasio, Erica; Erpicum, Sébastien ULg; Orsi, Enrico et al

in 6th International Conference on Scour and Erosion (ICSE) (2012, August)

Despite simple geometries, flow in shallow rectangular reservoirs show complex recirculation patterns, which strongly influence the sediment deposits and, in practice, affect the operation and maintenance ... [more ▼]

Despite simple geometries, flow in shallow rectangular reservoirs show complex recirculation patterns, which strongly influence the sediment deposits and, in practice, affect the operation and maintenance costs of such facilities. Based on composite modelling, this research characterizes flow and sedimentation patterns in geometric conditions which have not been investigated so far. Velocity fields developing in rectangular shallow reservoirs (h = 0.2 m) with different asymmetric locations of the inlet and the outlet channels were experimentally investigated. Tests were performed in a reservoir geometry (4.5 m x 4 m) characterized by a stable symmetric flow pattern in the basic symmetric configuration, at constant hydraulic conditions; the aim was to evaluate exclusively the effect of channels displacing on the flow patterns and on the sedimentation of suspended solids. Horizontal velocity components were measured by ultrasound velocity profilers in the entire reservoir and maps of velocity vectors were obtained. Velocity measurements were performed both with clear water and with an inflowing suspended load. At the end of the experiments sediments deposits thickness on the entire reservoir bottom was measured by a laser light method, and maps of sediments deposits thickness were produced. Reservoir trapping efficiency was evaluated, but no significant influence of inlet and outlet channels location on trapping efficiency was observed. Numerical simulations were performed with the depth-averaged model WOLF 2D, in order to assess the ability of the model to reproduce the different types of flow patterns found in the experiments. In particular, a sensitivity analysis on bottom roughness as well as on the turbulence closure model and parameter was performed, in order to analyze a possible feedback effect of sediment deposits and/or suspended load on the type of flow pattern. [less ▲]

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See detailExperiment investigations of 2D stationary mixed flows and numerical conparison
Nguyen, Van Nam ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg et al

in Proceedings of the 2nd IAHR Europe Congress (2012, June 27)

Experimental investigations have been carried out to observe the mechanisms of stationary mixed flows in a flume combined with a conduit. The tests have been performed for varied discharges, considering ... [more ▼]

Experimental investigations have been carried out to observe the mechanisms of stationary mixed flows in a flume combined with a conduit. The tests have been performed for varied discharges, considering two 4.2m long rectangular channels 0.985m wide and 0.50m deep, linked by a 2m long closed conduit with a 0.20m wide and 0.15m high rectangular cross-section, located at the channels bottom along the right bank. The experimental results have been compared with numerical modeling performed using an original 2D numerical model, dealing with mixed flows using a single set of equations. [less ▲]

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See detailExperimental analysis of PKW hydraulic performance and geometric parameters optimum
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Pirotton, Michel ULg et al

in Proceedings of International workshop on Piano Key Weir for In-stream Storage and Dam Safety - PKWISD-2012 (2012, June 01)

In the scope of dam rehabilitation to manage floods increase or to increase water storage, the Piano Key Weir is a good solution for concrete dams. The efficiency of Piano Key Weirs is now well ... [more ▼]

In the scope of dam rehabilitation to manage floods increase or to increase water storage, the Piano Key Weir is a good solution for concrete dams. The efficiency of Piano Key Weirs is now well demonstrated through various experimental studies. Even if parametrical studies are currently undertaken, the definition of the optimal shape to give to the structure is still missing due to the lack of knowledge in the influence of the large set of geometrical parameters. This paper presents the results of a combine experimental and numerical study of PKW. On the one hand, the study, led on a large scale model of PKW, aims at defining the main parameters influencing the hydraulic behaviour of the structure. On the other hand, the influence of these main parameters has been studied on several scale models considering variation of the weir height, the keys widths and the overhangs lengths. The results of the experiments enable to define optimal values for a common variation of these parameters. [less ▲]

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