References of "Erpicum, Sébastien"
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See detailNumerical and physical hydraulic modelling of Piano Key Weirs
Erpicum, Sébastien ULg; Machiels, Olivier ULg; Dewals, Benjamin ULg et al

in Proceedings of the 4th Int. Conf. on Water Resources and Renewable Energy Development in Asia (2012, March)

During the last few years, several piano key weirs (PKWs) have been built in France by Electricité de France (EDF). Thanks to the reduced footprint and high release capacities of this new type of weir ... [more ▼]

During the last few years, several piano key weirs (PKWs) have been built in France by Electricité de France (EDF). Thanks to the reduced footprint and high release capacities of this new type of weir, making it particularly suited for concrete dams rehabilitation, lots of other projects in varied countries are under construction or study. The prototype use of PKW requires knowledge about its structural behaviour, hydraulic capacities as well as integration into dams’ environment. This paper aims at presenting numerical and physical modelling works performed at the University of Liege to address the last two points. In particular, large scale physical modelling and parametric scale models enabled to understand the hydraulic behaviour of the structure and to highlight its main geometric parameters as well as their best variation interval depending on various criteria related to the weir design (discharge efficiency, cost…). A 1D numerical model has also been developed based on these experimental investigations. It enables to predict in a few minutes, with 10% accuracy, the discharge capacity of a given PKW geometry on its usual operation head range. This model, available as a freeware on http://www.pk-weirs.ulg.ac.be, constitutes a key tool for the first design of such weirs. Finally, the scale model studies of major projects such as Raviège dam (France) for EDF and Ouldjet Mellegue Project (Algeria) for Coyne et Bellier – Tractebel Engineering enable to confront theoretical predictions with experimental results and to address the problem of PKW integration on dam crests. [less ▲]

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See detailFlow patterns and sediment deposition in rectangular shallow reservoirs
Dufresne, Matthieu; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

in Water & Environment Journal (2012), 26(4), 504-510

This work involves the experimental investigation of flow patterns, preferential regions of deposition and trapping efficiency in rectangular shallow reservoirs. The main flow patterns that can be ... [more ▼]

This work involves the experimental investigation of flow patterns, preferential regions of deposition and trapping efficiency in rectangular shallow reservoirs. The main flow patterns that can be encountered in rectangular shallow reservoirs are described: symmetrical flows without any reattachment point (S0), asymmetrical flows with one reattachment point (A1), and asymmetrical flows with two reattachment points (A2). The influence of geometrical and hydraulic parameters on reattachment lengths is intensively investigated. A shape parameter is introduced to classify symmetrical and asymmetrical flows. For each flow pattern, the preferential regions of deposition are studied. To conclude, a number of practical recommendations are given. Reservoirs with a shape parameter lower than 6.2 limit sediment deposition. Reservoirs with a shape parameter greater than 6.8 are favourable for sediment deposition. Finally, perspectives for maximizing and minimizing deposition are given, respectively by exploiting the great trapping potential of the flow pattern A1 and the poor trapping potential of the flow pattern S0. [less ▲]

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See detailThe Taoussa project (Mali): an example of effective composite modeling
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Vuillot, Jean Marie et al

in 4th IAHR International Symposium on Hydraulic Structures (2012, February)

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is obviously the more effective response to most flow ... [more ▼]

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is obviously the more effective response to most flow problems analyses. This paper presents the results of a successful application of such a composite numerical – physical study carried out by the Research Group Hydraulics in Environmental and Civil Engineering (former HACH) of the University of Liège on behalf of Coyne et Bellier (Tractebel Engineering). It concerned, at the stage of detailed draft, the hydraulic study of the Taoussa Project on the Niger River in Mali. The studies, performed in less than 6 months, focused on the flow characteristics at the scale of the reservoir and the river, using the numerical approach, as well as on hydrodynamic details in the spillway using a large scale factor physical model with boundary conditions defined on the basis of numerical modeling. [less ▲]

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See detailExperimental study of velocity fields in rectangular shallow reservoirs
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (2012), 50(4), 435-436

The Authors of the discussed paper present the results of an experimental study to improve the flow classification in rectangular shallow reservoirs. Although previous papers have paved the way for this ... [more ▼]

The Authors of the discussed paper present the results of an experimental study to improve the flow classification in rectangular shallow reservoirs. Although previous papers have paved the way for this classification (Dewals et al. 2008, Dufresne et al. 2010), the Authors are complemented for the detailed flow field measurements conducted for a high number of reservoir geometries. For the tested hydraulic conditions, the Authors report a transition zone corresponding to an ‘unstable’ flow pattern. Repeated tests under similar conditions lead alternately to a symmetric or an asymmetric flow field. In this discussion, it is intended below to shed light on this transition zone using 2D numerical simulations. The Authors state that the flow in the transition zone is sensitive to so-called ‘external perturbations’, whereas we argue that the flow is particularly influenced by the initial test conditions. Using a particular post-processing of the computed flow fields, a hysteresis effect is detected. [less ▲]

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See detailSemi-explicit modelling of watersheds with urban drainage systems
Dewals, Benjamin ULg; Archambeau, Pierre ULg; Khuat Duy, Bruno et al

in Engineering Applications of Computational Fluid Mechanics (2012), 6(1), 46-57

A trade-off methodology has been developed to account for impervious surfaces and drainage effects accurately, without the need for modelling the entire drainage network in detail. Undrained impervious ... [more ▼]

A trade-off methodology has been developed to account for impervious surfaces and drainage effects accurately, without the need for modelling the entire drainage network in detail. Undrained impervious areas have been distinguished from drained ones. Rain falling on the former has been discharged as overland flow, whereas flow on the later has been routed separately using “virtual pipes”, which enable a simplified process-oriented modelling of the drainage network. [less ▲]

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See detailMultidimensional flow modelling to guide hydromorphological restoration of an Alpine river
Rulot, François ULg; Detrembleur, Sylvain; Archambeau, Pierre ULg et al

in Proceedings of the 9th International Symposium on Ecohydraulics 2012 (2012)

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See detailDealing with sediment transport over partly non-erodible bottoms
Rulot, François ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Tullis, Blake; Chanson, Hubert (Eds.) Proc. 4th International Junior Researcher and Engineer Workshop on Hydraulic Strucutres, IJREWHS’12 (2012)

In depth-averaged flow and morphodynamic models using a finite volume discretization based on explicit time integration, a specific difficulty can arise during a computation: the computed sediment level ... [more ▼]

In depth-averaged flow and morphodynamic models using a finite volume discretization based on explicit time integration, a specific difficulty can arise during a computation: the computed sediment level can become lower than the level of a non-erodible bottom. The original developments presented in this paper enable to correct the non-physical sediment levels. The method, based on iterative limitation of the outward fluxes, is perfectly mass conservative and remains computationally efficient. The resulting model has been validated with several 1D benchmarks leading to configurations with sediment transport over non-erodible bottom. Two interesting experimental benchmarks are highlighted in this paper to show the efficiency of numerical simulations. In these benchmarks, the computation time has been verified not to increase by more than 15% when using the new method. [less ▲]

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See detailModelling sediment transport over partially non-erodible bottoms
Rulot, François ULg; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

in International Journal for Numerical Methods in Fluids (2012), 70(2), 186-199

In depth- and cross section-averaged morphodynamic models, based on explicit time integration, it may happen that the computed bed level becomes lower than the top level of a non-erodible layer (e.g ... [more ▼]

In depth- and cross section-averaged morphodynamic models, based on explicit time integration, it may happen that the computed bed level becomes lower than the top level of a non-erodible layer (e.g. concrete, bedrock or armoured layer). This is a standard pitfall which has been addressed in different ways. In this paper, we present an original approach for avoiding computation of non-physical bed levels, using an iterative procedure to correct the outward sediment fluxes. The procedure is shown to be computationally efficient while it achieves a high accuracy in terms of mass conservation. We compare our original approach with the existing Struiksma’s method and with a reformulation of the problem in terms of mathematical optimization of a linear or non-linear objective function under linear constraints. The new procedure has been incorporated into an existing finite volume morphodynamic model. It has been validated with several 1D benchmarks leading to configurations with sediment transport over non-erodible bottom. The computation time has been verified not to increase by more than 15% compared to runs without non-erodible bottom. [less ▲]

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See detailTransboundary assessment of the effect of climate change on river Meuse: flood wave selection for hydraulic modelling from Ampsin (B) to Maaseik (NL)
Dewals, Benjamin ULg; Detrembleur, Sylvain ULg; Becker, Bernhard et al

in Proc. 2nd IAHR Europe Congress: Water - infinitely deformable but still limited (2012)

This paper addresses high resolution inundation modelling in a transboundary context. In particular, flood wave propagation and inundation characteristics are simulated over a stretch of almost 100 km of ... [more ▼]

This paper addresses high resolution inundation modelling in a transboundary context. In particular, flood wave propagation and inundation characteristics are simulated over a stretch of almost 100 km of river Meuse across the Belgian-Dutch border, using 2D fully dynamic modelling. This transboundary hydraulic simulation requires inflow hydrographs to be prescribed as upstream boundary conditions. However, existing procedures for generating flood wave hydrographs differ between the concerned regions. Therefore, we review the main characteristics of the existing regional procedures and compare the resulting synthetic hydrographs. Besides, transnational hydrological scenarios have been developed to investigate the impact of climate change on flood risk along river Meuse in both countries. [less ▲]

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See detailTowards improved operation rules for the Vesdre reservoirs
Detrembleur, Sylvain; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

Report (2012)

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See detailInfluence of the relative alveoli widths on Piano Key Weirs efficiency for varied weir heights
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Proceedings of Int. Symp. on Dams for a changing world (2012)

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. Indeed, its labyrinth shape allows discharge capacities ... [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. Indeed, its labyrinth shape allows discharge capacities until 4 times more important than traditional ogee-crested weirs and 10 percent more important than labyrinth weirs of same horizontal geometry. Furthermore, the use of up- and downstream overhangs reduces drastically its footprint and enables its use directly on dams crest. 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 about the influence of the relative alveoli widths on the Piano Key Weir discharge capacity. 14 models have been tested providing results for a large range of the inlet to outlet widths ratio and considering variation of the weir height in accordance with former studies. The results of the experiments enable to define optimal values for a common variation of these two parameters. [less ▲]

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See detailComposite modeling to enhance hydraulic structures studies
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Proceedings of SimHydro 2012 (2012)

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is obviously the more effective response to most flow ... [more ▼]

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is obviously the more effective response to most flow problems analyses. Indeed, it enables combining the inherent advantages of both approaches, which are complementary, while being beneficial to the delays as well as the quality of the analysis. The paper presents the way composite modeling is applied for years at the HECE - Laboratory of Engineering Hydraulics (University of Liege) to enhance hydraulic structures studies. Besides numerical model validation for which experimental benchmarks constitute the first reliable data source, simultaneous application of both modeling approaches may be envisaged in three different ways. Composite modeling may be used to increase the scale factor of physical models by reducing the layout of the real structure to be modeled, to provide a better answer to specific problems than a single approach study or to maximize the efficiency of experimental tests by reducing the range of variation of the unknown parameters to be tested. For each of these three issues depicted in the paper, several examples show how the combined use of efficient numerical solvers together with physical scale models enables to increase the overall quality and scope of the analyses while decreasing the delays and possibly the costs. [less ▲]

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See detailOn the Piano Key Weir hydraulics
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Rutschmann, Peter; Grünzner, Markus; Stephan, Hötzl (Eds.) Proceedings of 2nd IAHR Europe Congress (2012)

The Piano Key Weir (PKW) is a kind of labyrinth weir with a geometry that uses overhangs to reduce the base length. The PKW can thus be directly placed on the crest of an existing dam. Together with its ... [more ▼]

The Piano Key Weir (PKW) is a kind of labyrinth weir with a geometry that uses overhangs to reduce the base length. The PKW can thus be directly placed on the crest of an existing dam. Together with its high discharge capacity for low heads (up to four times as high as an ogee-crested weir of same length), this geometric feature makes the PKW an interesting solution for dam rehabilitation and for new dam projects with a high level of constraints (design discharge, available space, reservoir storage, ...). PKW has been initially designed in 2001 and built for the first time in 2006 by “Electricité de France (EDF)”. Even if the first experimental studies confirmed its appealing discharge capacities, the flow upstream, over and downstream of this complex structure is still poorly described. Following a 3 years intensive experimental and numerical study of PKW hydraulics, the paper presents a general description of the hydraulic behavior of the PKW. It aims to explain the influence of the large set of geometric parameters on the discharge capacity. The assumptions of the study link various phenomenons depicted in the literature about PKW and an evaluation of their relative influence on the PKW efficiency is given. The role of the crests shape, the crests submersion, the nappes interactions, the crests approach conditions, the position of the control section and the head losses are analyzed. Design advices are also given. [less ▲]

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See detailInfluence of weir height and keys slope on PKW discharge
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Proceedings of 4th IAHR International Symposium on Hydraulic Structures (2012)

Piano Key Weir is a cost effective solution for rehabilitation as well as for new dam projects with a high level of constraints (limited space, high specific flood discharge, small reservoir level ... [more ▼]

Piano Key Weir is a cost effective solution for rehabilitation as well as for new dam projects with a high level of constraints (limited space, high specific flood discharge, small reservoir level variation). While the higher efficiency of the Piano Key Weir compared to standard linear weirs has already been demonstrated, its optimal geometry is still poorly defined. Even if former studies highlighted the main influence of the weir height on its discharge capacity, the distinction between weir height effect and keys slope one is not so straight forward. In order to distinguish the influence of these two parameters, the use of parapet walls has been tested to increase weir height keeping bottom slope constant, and to decrease keys slope keeping the weir height constant. The experimental results presented in this paper enable to distinguish the relative influences of the keys bottom slope and of the weir height on the Piano Key Weir release capacity. Comparisons with former experimental results as well as design guidelines are also provided. [less ▲]

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