References of "Pirotton, Michel"
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See detailComputing flooding of crossroads with obstacles using a 2D numerical model (Discussion)
Bruwier, Martin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (in press)

Based on an operational 2D shallow-water model, the Authors computed subcritical dividing flow at a three-branch crossroad, considering obstacles located at different positions. The numerical predictions ... [more ▼]

Based on an operational 2D shallow-water model, the Authors computed subcritical dividing flow at a three-branch crossroad, considering obstacles located at different positions. The numerical predictions were compared to observations from Mignot et al. (2013). Two issues are addressed here, related respectively to the efficiency and relevance of the turbulence model, and to the representation of the obstacles in operational flood models. [less ▲]

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See detailPressure and velocity on an ogee spillway crest operating at high head ratio: experimental measurements and validation
Peltier, Yann; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Journal of Hydro-Environment Research (in press)

This paper aims at validating pressure and velocity measurements conducted in two physical scale models of an ogee spillway crest operating at heads largely greater than the design head. The design head ... [more ▼]

This paper aims at validating pressure and velocity measurements conducted in two physical scale models of an ogee spillway crest operating at heads largely greater than the design head. The design head of the second model is 50% smaller than the one of the first model. No pier effect or air venting is considered in the study. The velocity field is measured by Bubbles Image Velocimetry. The relative pressure along the spillway crest is measured using pressure sensors. Comparison of measured velocities between both spillways indicates low scale effects, the scaled-profiles collapsing in most parts of the flow. By contrast, measurements of relative pressure along the spillway crest differ for large heads. A theoretical velocity profile based on potential flow theory and expressed in a curvilinear reference frame is fitted to the velocity measurements, considered as reference, for extrapolating the velocity at the spillway crest. Comparing the extrapolated velocity at the spillway crest and the velocity calculated from the relative pressure considering a potential flow finally emphasizes that bottom pressure amplitudes seem overestimated for the larger spillway, while an averaging effect might operate for the pressure measurements on the smaller spillway. [less ▲]

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See detailDevelopment trajectory of an integrated framework for the mitigation of future flood risk: results from the FloodLand project
Saadi, Ismaïl ULg; Bruwier, Martin ULg; El Saeid Mustafa, Ahmed Mohamed ULg et al

in Transportation Letters: The International Journal of Transportation Research (in press)

In this paper, the development trajectory of an integrated framework for the mitigation of future flood risk of the Ourthe river basin in Belgium is discussed. The paper contributes to the state-of-the ... [more ▼]

In this paper, the development trajectory of an integrated framework for the mitigation of future flood risk of the Ourthe river basin in Belgium is discussed. The paper contributes to the state-of-the-art by presenting an integrated multidisciplinary framework capable of making long-term projections (time horizon 2050 and 2100) with the objective of mitigating future flood risk by proposing alternative land-use scenarios. It bridges numerous different fields, including urban planning, transport engineering, hydrology, geology, environmental engineering, and economics. The overall design and validation results of the different sub-modules of the framework are presented, and ongoing and future enhancements are highlighted. [less ▲]

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See detailOvertopping induced failure of non-cohesive, homogenous fluvial dikes
Rifai, Ismail ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Water Resources Research (in press)

Accurate predictions of breach characteristics are necessary to reliably estimate the outflow hydrograph and the resulting inundation close to fluvial dikes. Laboratory experiments on the breaching of ... [more ▼]

Accurate predictions of breach characteristics are necessary to reliably estimate the outflow hydrograph and the resulting inundation close to fluvial dikes. Laboratory experiments on the breaching of sand-filled fluvial dikes were performed, considering a flow parallel to the dike axis. The breach was triggered by overtopping of the dike crest. A detailed monitoring of the transient evolution of the breach geometry was conducted, providing key insights into the gradual and complex processes involved in fluvial dike failure. The breach develops in two phases: (1) the breach becomes gradually wider and deeper eroding on the downstream side along the main channel, and (2) breach widening controlled by side slope failures, continuing in the downstream direction only. Increasing the inflow discharge in the main channel, the breach formation time decreases significantly and the erosion occurs preferentially on the downstream side. The downstream boundary condition has a strong influence on the breach geometry and the resulting outflow hydrograph. [less ▲]

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See detailMaximum energy dissipation to explain velocity fields in shallow reservoirs
Westhoff, Martijn; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (in press)

Shallow reservoirs are often used as sediment traps or storage basins, in which sedimentation depends on the flow pattern: Short rectangular reservoirs reveal a straight jet from inlet to outlet with on ... [more ▼]

Shallow reservoirs are often used as sediment traps or storage basins, in which sedimentation depends on the flow pattern: Short rectangular reservoirs reveal a straight jet from inlet to outlet with on both sides identical recirculation zones. In longer reservoirs, the main jet reattaches to the side of the reservoir leading to a small and a large recirculation zone. Previous studies found an empirical geometric relation describing the switch between these two flow patterns. In this study, we demonstrate, with a simple analytical model, that this switch coincides with a maximization of energy dissipation in the shear layer between the main jet and recirculation zones: Short reservoirs dissipate more energy when the flow pattern is symmetric, while longer reservoirs dissipate more energy with an asymmetric pattern. This approach enables to predict the flow patterns without detailed knowledge of small scale processes, potentially useful in the early phase of reservoir design. [less ▲]

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See detailInfluence of urban patterns on flooding
Bruwier, Martin ULg; Mustafa, Ahmed; Aliaga, Daniel et al

in E-proceedings of the 37th IAHR World Congress (2017, August)

The goal of this paper is to identify the respective influence of different characteristics of urban patterns on urban flooding. A set of 2,290 alternate urban patterns was generated randomly using an ... [more ▼]

The goal of this paper is to identify the respective influence of different characteristics of urban patterns on urban flooding. A set of 2,290 alternate urban patterns was generated randomly using an urban generator tool providing the geometry of buildings and their relative location to the ground, over a square area of 1 km². Steady 2-D hydraulic computations were performed for these 2,290 different urban patterns with identical hydraulic boundary conditions. The computational time was reduced by using an anisotropic porosity model. This model uses relatively coarse computational cells; but preserves information from the detailed topographic data through the use of porosity parameters. Based on the computed maps of waterdepths for the 2,290 urban patterns, a sensitivity analysis based on a multiple linear regression was performed to outline the most influential urban characteristics. [less ▲]

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See detailShallow water model with anisotropic porosity for flood modelling on Cartesian grids
Bruwier, Martin ULg; Archambeau, Pierre ULg; Erpicum, Sébastien ULg et al

Conference (2017, June)

Detailed topographic data have become widely available for inundation mapping. While the use of such high-resolution data enables the computation of flow variables at a fine scale, the computation time ... [more ▼]

Detailed topographic data have become widely available for inundation mapping. While the use of such high-resolution data enables the computation of flow variables at a fine scale, the computation time remains too high for many practical applications. In contrast, models solving the shallow-water equations with porosity provide a useful tool to improve the computational efficiency, while preserving to some extent the detailed topographic information through porosity parameters. In this study, we present a new model solving the fully dynamic shallow water equations with anisotropic porosity based on Cartesian grids. Using a Cartesian grid leads to specific challenges, particularly as regards the definition of the conveyance porosities at the cell edges. Moreover, the presented model is further improved by a merging method so as to increase the computational efficiency without affecting the overall accuracy. The performance of the model has been evaluated based on a wide range of test cases, which confirm the validity of the model and the benefits of such a modelling framework. [less ▲]

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See detailSystematic flood modelling to support flood-proof urban design
Bruwier, Martin ULg; Mustafa, Ahmed; Aliaga, Daniel et al

Poster (2017, April)

Urban flood risk is influenced by many factors such as hydro-meteorological drivers, existing drainage systems as well as vulnerability of population and assets. The urban fabric itself has also a complex ... [more ▼]

Urban flood risk is influenced by many factors such as hydro-meteorological drivers, existing drainage systems as well as vulnerability of population and assets. The urban fabric itself has also a complex influence on inundation flows. In this research, we performed a systematic analysis on how various characteristics of urban patterns control inundation flow within the urban area and upstream of it. An urban generator tool was used to generate over 2,250 synthetic urban networks of 1 km². This tool is based on the procedural modelling presented by Parish and Müller (2001) which was adapted to generate a broader variety of urban networks. Nine input parameters were used to control the urban geometry. Three of them define the average length, orientation and curvature of the streets. Two orthogonal major roads, for which the width constitutes the fourth input parameter, work as constraints to generate the urban network. The width of secondary streets is given by the fifth input parameter. Each parcel generated by the street network based on a parcel mean area parameter can be either a park or a building parcel depending on the park ratio parameter. Three setback parameters constraint the exact location of the building whithin a building parcel. For each of synthetic urban network, detailed two-dimensional inundation maps were computed with a hydraulic model. The computational efficiency was enhanced by means of a porosity model. This enables the use of a coarser computational grid , while preserving information on the detailed geometry of the urban network (Sanders et al. 2008). These porosity parameters reflect not only the void fraction, which influences the storage capacity of the urban area, but also the influence of buildings on flow conveyance (dynamic effects). A sensitivity analysis was performed based on the inundation maps to highlight the respective impact of each input parameter characteristizing the urban networks. The findings of the study pinpoint which properties of urban networks have a major influence on urban inundation flow, enabling better informed flood-proof urban design. [less ▲]

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See detailOn the transition between symmetric and asymmetric flow in rectangular shallow reservoirs - a case of maximum energy dissipation?
Westhoff, Martijn; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in 4th International Symposium of Shallow Flows (2017)

Shallow reservoirs are often used as sediment traps or storage basins, in which sedimentation depends on the flow pattern. Short rectangular reservoirs reveal a straight jet from inlet to outlet with ... [more ▼]

Shallow reservoirs are often used as sediment traps or storage basins, in which sedimentation depends on the flow pattern. Short rectangular reservoirs reveal a straight jet from inlet to outlet with identical recirculation zones on both sides. In longer reservoirs, the main jet reattaches to the side of the reservoir leading to small and large recirculation zones. Previous studies have found an empirical geometric relation describing the switch between these two flow patterns. In this study, we demonstrate, with a simple analytical model, that this switch coincides with a maximization of energy dissipation in the shear layer between the main jet and recirculation zones: Short reservoirs dissipate more energy when the flow pattern is symmetric, while longer reservoirs dissipate more energy with an asymmetric pattern. This approach enables the prediction of the flow patterns without detailed knowledge of small scale processes, potentially useful in the early phase of reservoir design. [less ▲]

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See detailCould Piano key weirs be subject to nappe oscillations?
Lodomez, Maurine ULg; Pirotton, Michel ULg; Dewals, Benjamin ULg et al

in 3rd International Workshop on Labyrinth and Piano Key Weirs - PKW 2017 (2017)

Nappe oscillation may affect a variety of free overflow hydraulic structures operating at low heads such as crest gates and various types of weirs. This phenomenon produces oscillations in the thin nappe ... [more ▼]

Nappe oscillation may affect a variety of free overflow hydraulic structures operating at low heads such as crest gates and various types of weirs. This phenomenon produces oscillations in the thin nappe cascading downstream of the control structure. These oscillations can result in a high noise levels that may affect people and structures located nearby. With long linear and thin overtopping walls, piano key weirs might be subject to strong nappe oscillation risks, as a few documented cases with labyrinth weirs. However, the specific geometric features of piano key weirs, such as the outlet ramps or the limited width of the inlet apex, could perhaps prevent the development of nappe oscillation. In this paper, a prototype-scale linear weir is operated to assess the risk of nappe oscillations on a piano key weir like configuration (sidewall). In particular, the effect of the weir width and inclined apron is analyzed. The experimental results show that nappe oscillation development should not occur on piano key weir, contrary to what might be observed on a labyrinth weir with the same crest. [less ▲]

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See detailEvaluation et gestion des scenarii de dysfonctionnement des barrages-réservoirs en Belgique
Liégeois, Benoît; Pirotton, Michel ULg; Dewals, Benjamin ULg et al

in Sûreté des barrages et enjeux (2016, November)

Belgium has fifteen structures included in the list of large dams of the International Committee on Large Dams. Six are managed by Engie Company, the other nine are owned by the Walloon regional public ... [more ▼]

Belgium has fifteen structures included in the list of large dams of the International Committee on Large Dams. Six are managed by Engie Company, the other nine are owned by the Walloon regional public authority. The Belgian legislator has never enacted specific rules for large dams. However, managers have always been concerned with this issue. They developed procedures and methods that were subject to exchanges of experience with their counterparts, in particular through the Belgian Committee on Large Dams. In this ongoing research of security, the impact of multiple failure scenarios (dam break, quick emptying …) on the people and the environment downstream of dams is a particular focal point. An impact study has been conducted for the main plants. This study is based on a deterministic numerical method. The methodology, the assumptions regarding the failure mode or emptying and the lessons learned from the analyses are presented. These results are an important step in the assessment and the management of risks. Indeed, regulations were recently enacted for the management and the coordination of any activity likely to seriously impact public safety during crisis periods. These rules apply therefore for large dams. In this context, managers have established an emergency plan for each structure. This paper provides a broad overview on the issues of the evaluation and the management of dysfunction risks of Belgian dams, as well as on approaches and collaborations initiated between the private managers and public authority. [less ▲]

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See detail1-D shallow water model for industrial practice: Application to the River Romanche
Goffin, Louis ULg; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

Scientific conference (2016, October 25)

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See detailA benchmark for urban flood modelling
Arrault, Anaïs; Finaud-Guyot, Pascal; Archambeau, Pierre ULg et al

Poster (2016, October 25)

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See detailMonitoring topography of laboratory fluvial dike models subjected to breaching based on a laser profilometry technique
Rifai, Ismail ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in International Symposium on River Sedimentation: Stuttgart 19th-22d september 2016 (2016, September)

Detailed reference viewed: 62 (15 ULg)