References of "Erpicum, Sébastien"
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See detailGeometric parameters influence on Piano Key Weir hydraulic performances
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Pirotton, Michel ULg et al

in Chanson, Hubert; Toombes, Luke (Eds.) Hydraulic Structures and Society – Engineering Challenges (2014, June)

The Piano Key Weir is a recent evolution of the traditional labyrinth weir. Thanks to a reduced foot print, this nonlinear weir can be placed on the top of gravity dams. The Piano Key Weir geometry ... [more ▼]

The Piano Key Weir is a recent evolution of the traditional labyrinth weir. Thanks to a reduced foot print, this nonlinear weir can be placed on the top of gravity dams. The Piano Key Weir geometry involves a large number of geometric parameters. Several experimental studies have been carried out to investigate the main geometric parameters influencing the weir hydraulic efficiency and to define their optimal value. In this paper, the experimental data gathered at the University of Liege are re-examined to show how the weir height, the keys widths and the overhangs positions influence, for a given crest length magnification ratio, the weir discharge capacity. The theoretical rating curve of a standard linear weir is considered for comparison. The analysis highlights that the keys widths and overhangs lengths ratios influence significantly the Piano Key Weir efficiency, but less than the weir height. Considering the above mentioned results, a cost efficient design proposed in the literature is also proved to be close to the hydraulic optimum. [less ▲]

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See detailMeandering flows in rectangular shallow reservoirs
Peltier, Yann ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg

Report (2014)

During this research, previously unexplored meandering flows in free-surface rectangular shallow reservoirs were investigated theoretically, experimentally and numerically. For the first time, a complete ... [more ▼]

During this research, previously unexplored meandering flows in free-surface rectangular shallow reservoirs were investigated theoretically, experimentally and numerically. For the first time, a complete description of the hydrodynamics of the meandering flows was obtained from laboratory experiments. An innovative procedure for the characterisation of the physics of the flow was developed based on several techniques, including Large Scale Particle Image Velocimetry (LSPIV), Proper Orthogonal Decomposition (POD) and a new topology algorithm. This research provides new insights into these fascinating meandering flows, of high practical relevance in civil and environmental engineering. Six papers were written and, so far, five of them have been accepted for publication (two in international journals and three in peer-reviewed international conference proceedings). [less ▲]

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See detailMeandering jets in shallow rectangular reservoirs: POD analysis and identification of coherent structures
Peltier, Yann ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Experiments in Fluids (2014), 55

The effect of the shallowness on meandering jets in a shallow rectangular reservoir is investigated. Four meandering flows were investigated in an experimental shallow rectangular reservoir. Their ... [more ▼]

The effect of the shallowness on meandering jets in a shallow rectangular reservoir is investigated. Four meandering flows were investigated in an experimental shallow rectangular reservoir. Their boundary conditions were chosen to cover a large range of friction numbers (defined with the sudden expansion width). Due to the unsteady characteristics of the flows, a Proper Orthogonal Decomposition of the fluctu-ating part of the surface velocity fields measured using LSPIV was used for discriminating the flow struc-tures responsible for the meandering of the jet. Less than 1 % of the calculated POD modes significantly contribute to the meandering of the jet and two types of instability are in competition in such a flow con-figuration. The sinuous mode is the dominant mode in the flow and it induces the meandering of the flow, while the varicose mode is a source of local mixing and weakly participates to the flow. The fluctuating velocity fields were then reconstructed using the POD modes corresponding to 80% of the total mean fluctuating kinetic energy and the coherent structures were identified using the residual vorticity, their centres being localised using a topology algorithm. The trajectories of the structures centres emphasize that at high friction number the coherent structures are small and laterally paired in the near, middle and far fields of the jet, while with decreasing friction number the structures merge into large horizontal vortices in the far-field of the jet, their trajectories showing more variability in space and time. The analysis of the stability regime finally reveals that the sinuous mode is convectively unstable and may become absolutely unstable at the end of the reservoir when the friction number is small. [less ▲]

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See detailLanduse change and future flood risk: the influence of micro-scale spatial patterns (FloodLand) - 1st progress report
Dewals, Benjamin ULg; Bruwier, Martin ULg; El Saeid Mustafa, Ahmed Mohamed ULg et al

Report (2014)

The goal of the project FloodLand is to investigate the complex interactions between landuse change and future flood risk. Landuse change is assumed to be mainly driven by population growth and socio ... [more ▼]

The goal of the project FloodLand is to investigate the complex interactions between landuse change and future flood risk. Landuse change is assumed to be mainly driven by population growth and socio-economic factors. It affects future flood risk by altering catchment hydrology as well as vulnerability in the floodplains; but the feedback effect of (the perception of) changes in flood hazard on landuse evolution is also considered. The research is based on a chain of modelling tools, which represent parts of the natural and human systems, including: landuse change modelling, transportation modelling as an onset for the estimation of indirect flood damage, continuous hydrological modelling (forced by precipitation and temperature data disturbed according to climate change scenarios), as well as efficient hydraulic modelling of inundation flow in the floodplains. Besides reproducing a broad spectrum of processes, the modelling approach spans over multiple scales, from the regional or catchment level down to the floodplain and building levels. This distinctive feature is reflected both within the individual models and through their combination involving fine-scale detailed analyses (or data) embedded within coarser models at a broader level. [less ▲]

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See detailContributions to transnational flood risk management in the Meuse basin
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in European Symposium on Flood Frequency Estimation and Implications for Risk Management (2014, March)

Experience in transboundary river basins emphasizes the need for more cooperative transnational water management. In this respect, the Interreg IVB project AMICE aims at developing a shared adaptation ... [more ▼]

Experience in transboundary river basins emphasizes the need for more cooperative transnational water management. In this respect, the Interreg IVB project AMICE aims at developing a shared adaptation strategy of the basin of the river Meuse to the hydrological impacts of climate change. The basin covers parts of France, Belgium, Germany and the Netherlands. The project combines scientific research with innovative natural and structural water retention measures, as well as enhanced transnational crisis management. In this framework, common climate and hydrological scenarios were derived for the time horizons 2021-2050 and 2071-2100. A “coordinated” procedure was set up to conduct the first hydraulic modelling of the entire river Meuse, from its spring to its mouth. For the considered climate scenarios, the increases in future flood levels were found about twice higher in the central part of the Meuse basin compared to the upper and lower parts. This distinctive spatial pattern results from the morphology of the valley. The characteristics of the hydraulic models used for this “coordinated” analysis differed significantly from one region to the other (e.g., 1D vs. 2D, steady vs. unsteady). Therefore, a more refined analysis was undertaken on a 100 km long stretch of the Meuse, crossing the border between Belgium and the Netherlands, using very similar (“harmonized”) models for the whole computation (2D unsteady models). As a result, the influence of using different interconnected models could be appreciated. The results of hydraulic modelling were used to conduct damage assessment based on a common methodology throughout the Meuse basin and combined with landuse change scenarios in the floodplains (change in vulnerability of the floodplains). In turn, several adaptation measures were tested, including upstream water retention, dredging as well as upgrade of flood defences and mobile weirs. Hydrological and hydraulic modelling was also performed for a sub-basin of the river Meuse, partly controlled by two large reservoirs. A detailed model of the operation rules of these reservoirs was implemented. This enabled to investigate the impact of the considered climate change scenarios on the performance of these multi-purpose reservoirs as well as to investigate possible enhancements in the operation rules, which may serve as adaptation measures to compensate for the detrimental effects of climate change. [less ▲]

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See detailCan the collapse of a fly ash heap develop into an air-fluidized flow? - Reanalysis of the Jupille accident (1961)
Stilmant, Frédéric ULg; Pirotton, Michel ULg; Archambeau, Pierre ULg et al

in Geomorphology (2014)

A fly ash heap collapse occurred in Jupille (Liege, Belgium) in 1961. The subsequent flow of fly ash reached a surprisingly long runout and had catastrophic consequences. Its unprecedented degree of ... [more ▼]

A fly ash heap collapse occurred in Jupille (Liege, Belgium) in 1961. The subsequent flow of fly ash reached a surprisingly long runout and had catastrophic consequences. Its unprecedented degree of fluidization attracted scientific attention. As drillings and direct observations revealed no water-saturated zone at the base of the deposits, scientists assumed an air-fluidization mechanism, which appeared consistent with the properties of the material. In this paper, the air-fluidization assumption is tested based on two-dimensional numerical simulations. The numerical model has been developed so as to focus on the most prominent processes governing the flow, with parameters constrained by their physical interpretation. Results are compared to accurate field observations and are presented for different stages in the model enhancement, so as to provide a base for a discussion of the relative influence of pore pressure dissipation and pore pressure generation. These results show that the apparently high diffusion coefficient that characterizes the dissipation of air pore pressures is in fact sufficiently low for an important degree of fluidization to be maintained during a flow of hundreds of meters. [less ▲]

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See detailExperimental investigation of meandering jets in shallow reservoirs
Peltier, Yann ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Environmental Fluid Mechanics (2014)

Meandering flows in rectangular shallow reservoirs were experimentally investi- gated. The characteristic frequency, the longitudinal wave length and the mean lateral exten- sion of the meandering jet ... [more ▼]

Meandering flows in rectangular shallow reservoirs were experimentally investi- gated. The characteristic frequency, the longitudinal wave length and the mean lateral exten- sion of the meandering jet were extracted from the first paired modes, obtained by a proper orthogonal decomposition of the surface velocity field measured by large scale PIV. The depth-normalised characteristic lengths and the Strouhal number were then compared to the main dimensionless numbers characterizing the experiments: Froude number, friction num- ber and reservoir shape factor. The normalised wave length and mean lateral extension of the meandering jet are neither correlated with the Froude number nor with the reservoir shape factor; but a clear relationship is found with the friction number. Similarly, the Strouhal num- ber is found proportional to a negative power of the friction number. In contrast, the Froude number and the reservoir shape factor enable to predict the occurrence of a meandering flow pattern: meandering jets occur for Froude number greater than 0.21 and for a shape factor smaller than 6.2. [less ▲]

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See detailMAT_LSPIV 4.0: User Manual
Peltier, Yann ULg; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

Software (2014)

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See detailMeandering jets in shallow rectangular reservoir
Peltier, Yann ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in 7th International Conference in River Hydraulics, River Flow 2014 (2014)

In this article, meandering flows in a shallow rectangular reservoir are experimentally and numerically investigated. Two experiments were performed in a smooth shallow horizontal flume and the surface ... [more ▼]

In this article, meandering flows in a shallow rectangular reservoir are experimentally and numerically investigated. Two experiments were performed in a smooth shallow horizontal flume and the surface velocity fields were measured by Large-Scale PIV (LSPIV). The flow conditions were chosen in such a way that the friction regime of both flows was different. These flows were then modelled using the academic code WOLF2D, which solves the 2D shallow water equations and uses a depth-averaged k- model for modelling turbulence. The main characteristics of the measured and simulated flows were finally extracted from a Proper Orthogonal Decomposition (POD) of the surface velocity fields and depth-averaged velocity fields respectively and were compared. When the mean fluctuating kinetic energy of the considered POD mode is greater than 1×10-5 m²/s², the numerical modelling and the experiments are in good agreement whatever the friction regime of the flow. [less ▲]

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See detailClimate-proofing of large reservoirs in Belgium by the development of enhanced operation rules
Bruwier, Martin ULg; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

in 3rd IAHR Europe Congress (2014)

Available climate change scenarios project drier summers and more humid winters for Belgium. This study addresses the impacts of those changes on the management of two multi-purpose reservoirs located in ... [more ▼]

Available climate change scenarios project drier summers and more humid winters for Belgium. This study addresses the impacts of those changes on the management of two multi-purpose reservoirs located in the Vesdre basin, and the search of enhanced operation rules to mitigate those changes. For this purpose, an integrated model is used, including a hydrological model of the Vesdre watershed, a hydraulic model of this river, a model of the dam complex operation rules and a flood risk model. Performance indicators of the dams are defined, representing drinking water production, damages due to floods, hydropower production and low-flow enrichment. First, a sensitivity analysis of the main parameters of the dam operation rules on the performance indicators is achieved. Afterwards, for two extreme climate scenarios at the time horizons 2021-2050 and 2071-2100, impacts of climate change on the reservoir performances are determined. Then, the results of the sensitivity analysis are used to indicate if climate change impacts may be mitigated by means of enhanced operation rules. [less ▲]

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See detailMathematical formulations of shallow water models with porosity for urban flood modeling
Bruwier, Martin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in ICHE 2014 : 11th International Conference on Hydroscience & Engineering (2014)

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See detailAcoustic velocity measurements for evaluating bed stability parameters
Duma, Diana ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

E-print/Working paper (2014)

Assessing the stability of riverbeds is a major issue in many aspects of hydraulic and river engineering. Although the Shields diagram remains the most widely accepted approach, it faces a number of ... [more ▼]

Assessing the stability of riverbeds is a major issue in many aspects of hydraulic and river engineering. Although the Shields diagram remains the most widely accepted approach, it faces a number of shortcomings. In particular, its ability to reflect the influence of turbulence on sediment motion becomes questionable when it is applied under strongly non-uniform flow conditions, which are of high practical relevance in hydraulic engineering. Therefore, new approaches were proposed, which relate the degree of damage of gravel beds to so-called bed stability parameters depending explicitly on the local intensity of flow turbulence. However, these new bed stability parameters are much more demanding in term of detailed description of the flow field and, in all studies so far, they were estimated based only on Laser Doppler Velocimetry or Particle Image Velocimetry. Here, we investigate for the first time the suitability of acoustic velocity measurement techniques to evaluate these bed stability parameters. The experiments focus on smooth-to-rough transitions and a quasi-uniform configuration is used as a reference. Flow velocities were obtained using two complementary devices: an Ultrasonic Velocity Profiler and a 3D Acoustic Doppler Velocimeter. The new experimental results show that relatively robust estimates of the new stability parameters can be obtained from the 3D acoustic measurements. [less ▲]

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See detailValidation of a SPH model for free surface flows
Goffin, Louis ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg et al

Conference (2014)

Detailed reference viewed: 39 (13 ULg)