References of "Machiels, Olivier"
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See detailEtat d'avancement des études expérimentales entamées à l'université de Liège
Machiels, Olivier ULg

Conference (2010, November 16)

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See detailHydraulic behavior of Piano Key Weirs: experimental approach
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Janssen, Robert; Chanson, Hubert (Eds.) 3rd Int. Junior Researcher and Engineer Worjshop on Hydraulic Structures (2010, May)

The Piano Key Weir (PKW) is a particular geometry of weir similar to a labyrinth shape that features overhanging cycle ends to reduce the base length. Together with its high discharge capacity for low ... [more ▼]

The Piano Key Weir (PKW) is a particular geometry of weir similar to a labyrinth shape that features overhanging cycle ends to reduce the base length. Together with its high discharge capacity for low heads, this geometric feature makes the PKW an interesting solution for dam rehabilitation, permitting the placement of the weir directly on dam crest. However, PKW stays a new type of weir, firstly designed in 2001 and built for the first time in 2006 by Electricité de France (EDF). Even if the first experimental studies confirmed its discharge capacities, lacks persist in the understanding of the flow behaviour upstream, along and downstream of this complex structure. This paper presents the mean results and observations obtained from experiments on a large scale model of PKW. The hydraulics of the structure is clarified based on measurements of water depths, pressures, velocities and discharges on each part of the weir. These observations explain the effect of geometric improvements proposed in former studies. [less ▲]

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See detailAnalyse expérimentale de l'influence des largeurs d'alvéoles sur la débitance des déversoirs en touches de piano
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Houille Blanche (2010), (2), 22-28

Within the framework of updating the release and storage capacities of existing reservoirs, the use of piano keys weirs (PKW) can be an interesting alternative either to increase the discharge of a free ... [more ▼]

Within the framework of updating the release and storage capacities of existing reservoirs, the use of piano keys weirs (PKW) can be an interesting alternative either to increase the discharge of a free weir without changing the weir layout or the reservoir level, or increase the reservoir level before discharge while keeping the weir layout and the level of safety. In order to help to the understanding of the behavior of this new type of weirs and to characterize their hydraulic potential, the results of an experimental study with for objectives to study the influence of the relative width of the inlets and outlets on the hydrodynamic characteristics of the structure are presented. A process oriented analytical formulation for the evaluation of the discharge coefficient of the PKW tested on scale models is proposed. It is in satisfactory agreement with the experimental results and leads to an objective evaluation of the optimal ratio of the alveoli widths. [less ▲]

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See detailContribution to the study of piano Key Weir hydraulics
Erpicum, Sébastien ULg; Machiels, Olivier ULg; Dewals, Benjamin ULg et al

in Proceedings of the 8th ICOLD European Club Symposium (2010)

Within the framework of updating the release and storage capacities of existing reservoirs, the use of piano key weirs (PKW) can be an interesting alternative either to increase the discharge of a free ... [more ▼]

Within the framework of updating the release and storage capacities of existing reservoirs, the use of piano key weirs (PKW) can be an interesting alternative either to increase the discharge of a free weir without changing the weir width on the dam crest nor the reservoir level, or to increase the threshold reservoir level before releasing water while keeping the weir width and the level of safety. Results of first experiments on scale models have shown the high efficiency of PKW in terms of discharge capacity. But, even if PKW projects start to be developed on real structures, lacks persist in the understanding of the flow behavior on this new type of weir, in the characterization of their hydraulic potential and in the availability of design guidelines. This paper presents the results of several research projects, based on both numerical and physical modeling, carried out on this topic at the Laboratory of Engineering Hydraulics of the University of Liege. The researches rely on physical experiments on scale models of idealized PKW elements or real structures, as well as on numerical modeling with specifically developed solvers. The paper presents an overview of these projects, emphasizing the most important results regarding PKW design and performance. [less ▲]

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See detail1D numerical approach to model the flow over a piano key weir (PKW)
Erpicum, Sébastien ULg; Machiels, Olivier ULg; Archambeau, Pierre ULg et al

in Proc. Int. Conf. SimHydro 2010: Hydraulic modeling and uncertainty (2010)

Piano Key Weir (PKW) is a new type of weir showing appealing hydraulic capacities, in particular for low heads. However, its complex geometry, with a large set of parameters, makes difficult the ... [more ▼]

Piano Key Weir (PKW) is a new type of weir showing appealing hydraulic capacities, in particular for low heads. However, its complex geometry, with a large set of parameters, makes difficult the understanding of the flow features and consequently the definition of an optimal design. In this paper, we investigate how a 1D numerical approach can predict the flow over a PKW and thus help in identifying the most relevant geometric parameters. After a detailed description of the numerical model, a comparison of the numerical results with experimental data is realized, showing promising results. [less ▲]

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See detailExperimental study of the hydraulic behavior of piano key weirs
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Proc. 17th Congress of the Asia and Pacific Division of the International Association of Hydro-Environment Engineering and Research (2010)

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See detailMéthode de pré-dimensionnement des PKW et application au barrage de la Raviège
Machiels, Olivier ULg

Conference (2009, October 23)

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See detailApproche numérique simplifiée et comparaison aux résultats expérimentaux
Machiels, Olivier ULg

Conference (2009, October 23)

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See detailModélisation physique à grande échelle d'un élément PKW
Machiels, Olivier ULg

Conference (2009, March 12)

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See detailContinuous formulation for bottom friction in free surface flows modelling
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in River Basin Management V (2009)

Bottom friction modelling is an important step in river flows computation with 1D or 2D solvers. It is usually performed using empirical laws established for uniform flow conditions or a modern approach ... [more ▼]

Bottom friction modelling is an important step in river flows computation with 1D or 2D solvers. It is usually performed using empirical laws established for uniform flow conditions or a modern approach based on turbulence analysis. Following the definition of the flow validity field of the main friction laws proposed in the literature, an original continuous formulation has been developed. It is suited to model river flows with a wide range of properties (water depth, discharge, roughness…). The efficiency of this new formulation, theoretically established and numerically adjusted, is demonstrated through various practical applications. [less ▲]

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See detailAnalyse expérimentale du fonctionnement hydraulique des déversoirs en touches de piano
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Actes du Colloque Dimensionnement et Fonctionnement des Evacuateurs de crues (2009)

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See detailBottom friction formulations for free surface flow modeling
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in 8th NCTAM Congress (2009)

Bottom friction modeling is an important step in river flows computation with 1D or 2D solvers. It is usually performed using empirical laws established for uniform flow conditions or a modern approach ... [more ▼]

Bottom friction modeling is an important step in river flows computation with 1D or 2D solvers. It is usually performed using empirical laws established for uniform flow conditions or a modern approach based on turbulence analysis. Following the definition of the flow validity field of the main friction laws proposed in the iterature, an original continuous formulation has been developed. It is suited to model river flows with a high variability of properties (water depth, discharge, roughness…). The efficiency of this new formulation, theoretically established and numerically adjusted, is demonstrated through various practical applications. [less ▲]

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See detailLarge scale experimental study of piano key weirs
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Proc. 33rd IAHR Congress: Water Engineering for a Sustainable Environment (2009)

Piano Key Weirs (PKW) are a new type of weir, showing very good flood release capacities as well as strong economic and structural benefits. However, lacks of understanding persist about the flow ... [more ▼]

Piano Key Weirs (PKW) are a new type of weir, showing very good flood release capacities as well as strong economic and structural benefits. However, lacks of understanding persist about the flow conditions on such structures. With the goal to fill some of these lacks, a combined experimental and numerical study has been undertaken at the Laboratory of Structures Hydraulics of the University of Liege. This paper presents the goals and the scientific strategy of this research. The first results of experiments being carried out on a large physical model of PKW are also depicted. These experiments lead to characterization of the flow behavior for low heads and enable to highlight the influence of the crest thickness and the outlet slope on the release capacity. [less ▲]

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See detailAnalyse théorique et numérique de l'influence de la formulation des termes de production et de dissipation dans les équations d'écoulement à surface libre
Machiels, Olivier ULg

Master's dissertation (2008)

Depuis toujours, l’homme sait la richesse mais aussi le danger que représente l’eau. Il a donc sans cesse essayé de la maitriser. Dans ce souci de maitrise des écoulements, la modélisation de ceux-ci ... [more ▼]

Depuis toujours, l’homme sait la richesse mais aussi le danger que représente l’eau. Il a donc sans cesse essayé de la maitriser. Dans ce souci de maitrise des écoulements, la modélisation de ceux-ci représente un enjeu économique important. Les termes de frottement et de turbulence des différentes formulations à la base de l’hydraulique jouent un rôle capital pour l’efficacité de ces modélisations. C’est pourquoi de nombreux auteurs se sont intéressés à décrire le plus correctement ces termes de production et de dissipation. Dans la large gamme de formulations de frottement et de turbulence existante, il convient cependant de faire un tri. En effet, à chaque loi est associé un domaine de validité dépendant des hypothèses d’études qui ont mené à son élaboration. De plus, le succès qu’ont connu certaines lois est principalement dû à leur caractère simplifié qui pourrait cacher un manquement de rigueur physique. L’étude menée lors de ce travail a permis dans un premier temps de catégoriser les différentes lois afin de pouvoir comparer leurs domaines de validité et définir ainsi les lois à utiliser pour chaque modélisation (écoulement stationnaire ou non, régime laminaire ou turbulent, rugosité de fond plus ou moins importante,…). Cette étude comparative, portée sur les lois usuelles de frottement, est validée sur base de modélisations numériques. Celles-ci ont été menées sur des écoulements de rivière mettant en évidence les caractéristiques d’écoulement étudiées. Ce travail a donc permis d’établir les domaines de validité des différentes lois existantes sur base d’une représentation la plus proche possible de la physique réelle des écoulements. Il a également permit la mise en place d’une formulation continue capable de représenter numériquement l’ensemble des écoulements apparaissant sur une zone donnée (variation de hauteur d’eau, de débit, de rugosité,…). [less ▲]

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