References of "Dewals, Benjamin"
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See detailTowards a New Design Equation for Piano Key Weirs Discharge Capacity
Bashiri Atrabi, Hamid ULg; Dewals, Benjamin ULg; Pirotton, Michel ULg et al

in Proc. of the 6th International Symposium on Hydraulic Structures (2016)

Piano Key weirs are Labyrinth like weirs which can be placed on the top of gravity dams. They represent a powerful solution to increase the discharge capacity of existing dam spillways. For proper design ... [more ▼]

Piano Key weirs are Labyrinth like weirs which can be placed on the top of gravity dams. They represent a powerful solution to increase the discharge capacity of existing dam spillways. For proper design it is necessary to accurately predict this discharge capacity. In this research, artificial neural network, multiple linear and nonlinear regressions are used to set up a new design equation for the discharge capacity of Piano Key weirs. The effect of each parameter on the discharge capacity of Piano Key weirs is tested in these models. Several non-dimensional parameters are used to define a functional relationship between the inputs and output. These parameters are built from the geometric dimensions of the structure such as weir height, inlet and outlet keys width, overhangs length, water head and side crest length. Previous experimental data, which were collected at the experimental laboratory of the research group Hydraulics in Environmental and Civil Engineering (HECE), University of Liege, are used for training and testing patterns of the models. Root mean square errors (RMSE) and coefficient of determination (R2) are used as comparing criteria for the evaluation of the models. The models’ results are compared with experimental results and other existing equations. [less ▲]

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See detailEnergy conservation properties of Ritter solution for idealized dam break flow
Dewals, Benjamin ULg; Bruwier, Martin ULg; Erpicum, Sébastien ULg et al

in Journal of Hydraulic Research (2016), 54(5), 581-585

We examine different aspects of energy conservation in the case of the analytical solution of Ritter for idealized dam break flow in a horizontal frictionless and dry channel. We detail the application of ... [more ▼]

We examine different aspects of energy conservation in the case of the analytical solution of Ritter for idealized dam break flow in a horizontal frictionless and dry channel. We detail the application of the unsteady Bernoulli equation in this case and highlight that the inertial effects cancel out when averaged over the whole flow region. We also show that the potential and kinetic contributions to the total mechanical energy in the flow region have a distinct and constant relative importance: potential energy accounts for 60 %, and kinetic energy for 40 % of the total mechanical energy. These properties of Ritter solution are rarely emphasized while they may be of practical relevance, particularly for the verification of numerical schemes with respect to their ability to ensure energy conservation. [less ▲]

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See detailSustainable hydraulics in the era of global change - Advances in water engineering and research
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

Book published by CRC Press (2016)

In an increasingly urbanized world, water systems must be designed and operated according to innovative standards in terms of climate adaptation, resource efficiency, sustainability and resilience. This ... [more ▼]

In an increasingly urbanized world, water systems must be designed and operated according to innovative standards in terms of climate adaptation, resource efficiency, sustainability and resilience. This grand challenge triggers unprecedented questions for hydro-environment research and engineering. Addressing these issues requires a deep understanding of basic processes in fluid mechanics, heat and mass transfer, surface and groundwater flow, among others. This book unveils latest research achievements and innovations which were presented at the 4th European Congress of IAHR in Liege (Belgium). These new developments rely on state-of-the-art modelling technologies, supported by the exponentially growing availability of data and computation power. The book will serve as a reference for professionals and decision-makers involved in various water-related sectors, such as hydraulic engineering, fluvial hydraulics, coastal engineering, water resources management and many more. [less ▲]

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See detailScale effects in physical piano key weirs models
Erpicum, Sébastien ULg; Tullis, Blake; Lodomez, Maurine ULg et al

in Journal of Hydraulic Research (2016)

With inertia and gravity representing the dominant forces for most open channel flow applications (e.g. weir flow), Froude similitude is commonly used for scaling hydraulic performance data from the model ... [more ▼]

With inertia and gravity representing the dominant forces for most open channel flow applications (e.g. weir flow), Froude similitude is commonly used for scaling hydraulic performance data from the model to prototype structures. With weir flow, as the upstream head decreases, however, the relevance of surface tension and viscosity forces can increase to the point when the model and prototype similitude is not fully achieved through Froude scaling. Such discrepancies are referred as size-scale effects, and among other things, can result in variations in the head–discharge relationship, nappe trajectory, and air entrainment. Published criteria for avoiding significant size-scale effects for free flow over linear weirs have suggested that minimal heads of ∼0.02 to 0.07m be respected, independently of the model size. In this study, the size-scale effect, minimum upstream head, and Weber number limits are investigated for four piano key weirs with geometric model scales of 1:1, 1:7, 1:15, and 1:25. [less ▲]

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See detailImpacts of urban expansion on future flood damage: A case study in the River Meuse basin, Belgium
Mustafa, Ahmed; Bruwier, Martin ULg; Teller, Jacques ULg et al

in Erpicum, Sébastien; Dewals, Benjamin; Archambeau, Pierre (Eds.) et al Sustainable Hydraulics in the Era of Global Change: Advances in Water Engineering and Research (2016)

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See detailHydrodynamics of long-duration urban floods: experiments and numerical modelling
Arrault; Finaud-Guyot, Pascal; Archambeau, Pierre ULg et al

in Natural Hazards & Earth System Sciences (2016), 16

Flood risk in urbanized areas raises increasing concerns as a result of demographic and climate changes. Hydraulic modelling is a key component of urban flood risk analysis. Yet, detailed validation data ... [more ▼]

Flood risk in urbanized areas raises increasing concerns as a result of demographic and climate changes. Hydraulic modelling is a key component of urban flood risk analysis. Yet, detailed validation data are still lacking for comprehensively validating hydraulic modelling of inundation flow in urbanized floodplains. ln this study, we present an experimental model of inundation flow in a typical European urban district and we compare the experimental observations with predictions by a shallow-water numerical model. The setup is 5 ll\X Sm and involves seven streets along each direction, leading to 49 intersections. Different inflow discharges and flow partitions were tested. The performance ofthe numerical model is assessed and the upscaling ofthe experimental observations to the field is discussed. [less ▲]

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See detailErosion and sedimentation in a hydropower project: assessing impacts and opportunities
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Schüttrumpf, Holger (Ed.) Offene Gewässer: Strahlwirkung, Fischaufstieg, Fischabstieg, Sedimente, Schadstoffe (2016)

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See detailHydrodynamic instabilities in shallow reservoirs: implications for sediment management
Peltier, Yann; de Cuyper, Anaïs; Erpicum, Sébastien ULg et al

Conference (2016)

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See detailDiscretization of the divergence formulation of the bed slope term in the shallow-water equations and consequences in terms of energy balance
Bruwier, Martin ULg; Archambeau, Pierre ULg; Erpicum, Sébastien ULg et al

in Applied Mathematical Modelling (2016)

In this research, the influence on energy balance of the discretization scheme of the divergence formulation of the bed slope term in the shallow-water equations is analysed theoretically (for a single ... [more ▼]

In this research, the influence on energy balance of the discretization scheme of the divergence formulation of the bed slope term in the shallow-water equations is analysed theoretically (for a single topographic step) and based on two numerical tests. Different values of the main parameter controlling the discretization scheme of the divergence formulation are analysed to identify the formulation which minimizes the energy variation resulting from the discretization. For a wide range of ambient Froude numbers and relative step heights, the theoretical value of the control parameter minimizing the energy variation falls within a very narrow range, which can reasonably be approximated by a single “optimal” value. This is a result of high practical relevance for the design of accurate numerical schemes, as confirmed by the results of the numerical tests. [less ▲]

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See detailCan the maximum power principle predict effective conductivities of a confined aquifer? A lab experiment
Westhoff, Martijn ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

Conference (2015, December 14)

Power can be performed by a system driven by a potential difference. From a given potential difference, the power that can be subtracted is constraint by the Carnot limit, which follows from the first and ... [more ▼]

Power can be performed by a system driven by a potential difference. From a given potential difference, the power that can be subtracted is constraint by the Carnot limit, which follows from the first and second laws of thermodynamics. If the system is such that the flux producing power (with power being the flux times its driving potential difference) also influences the potential difference, a maximum in power can be obtained as a result of the trade-off between the flux and the potential difference. This is referred to as the maximum power principle. It has already been shown that the atmosphere operates close to this maximum power limit when it comes to heat transport from the Equator to the poles, or vertically, from the surface to the atmospheric boundary layer. To reach this state of maximum power, the effective thermal conductivity of the atmosphere is adapted by the creation of convection cells. The aim of this study is to test if the soil’s effective hydraulic conductivity also adapts in such a way that it produces maximum power. However, the soil’s hydraulic conductivity adapts differently; for example by the creation of preferential flow paths. Here, this process is simulated in a lab experiment, which focuses on preferential flow paths created by piping. In the lab, we created a hydrological analogue to the atmospheric model dealing with heat transport between Equator and poles, with the aim to test if the effective hydraulic conductivity of the sand bed can be predicted with the maximum power principle. The experimental setup consists of two freely draining reservoir connected with each other by a confined aquifer. By adding water to only one reservoir, a potential difference will build up until a steady state is reached. The results will indicate whether the maximum power principle does apply for groundwater flow and how it should be applied. Because of the different way of adaptation of flow conductivity, the results differ from that of the atmosphere. [less ▲]

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See detailPotential damping of extreme floods in the river Meuse between Ampsin (B) and the Belgian-Dutch border
Bruwier, Martin ULg; Archambeau, Pierre ULg; Erpicum, Sébastien ULg et al

in Lenders, H.J.R.; Collas, F.P.L.; Geerling, G.W. (Eds.) et al Bridging gaps between river science, governance and management. Book of Abstracts NCR-Days 2015 (2015, October)

In the framework of the Interreg IVB project AMICE, hydraulic modelling of floods in the river Meuse was performed by coordinating existing models (Dewals et al. 2012a). The influence of climate change ... [more ▼]

In the framework of the Interreg IVB project AMICE, hydraulic modelling of floods in the river Meuse was performed by coordinating existing models (Dewals et al. 2012a). The influence of climate change scenarios was incorporated indirectly in the simulations through a transnational hydrological scenario (Drogue et al. 2010; Dewals et al. 2013). For a “wet” future climate, this scenario assumes that the peak discharge Q100 of the 100-year flood would increase by 15 % for the time horizon 2021-2050 and by 30 % for the time horizon 2071-2100. However, the design discharge currently used for planning in the Netherlands is higher than those considered to date in the AMICE project. From this perspective, it becomes relevant to analyse flood scenarios corresponding to a peak discharge above Q100+30 %, referred to hereafter as an “extreme” flood. The aim of the study is to give an appreciation of the potential damping of one extreme flood scenario along the river Meuse between Ampsin (Belgium) and the Belgian-Dutch border (Figure 1). This analysis is based on the hydraulic model WOLF 2D (Erpicum et al. 2010) applied to a coarse grid with simplifications in the schematisation. The hydraulic model WOLF 2D has been already used in several studies to simulate floods (Ernst et al. 2010; Beckers et al. 2013, Bruwier et al. 2015, Detrembleur et al. 2015). The coarsening of the grid for simulating the extreme flood scenario is necessary to preserve the computational efficiency, since both the total flood duration and the inundation extents (hence the number of grid cells) increase considerably between the Q100 + 30 % scenario considered previously and the extreme scenario considered here. [less ▲]

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See detailValidation and test cases for a free surface SPH model
Goffin, Louis ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg et al

in Advances in hydroinformatics - Simhydro 2014 (2015, September)

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See detailPhysical modeling of lateral dike breaching due to overtopping
Rifai, Ismail ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in River, Coastal and Estuarine Morphodynamics, RCEM 2015 (2015, August)

Dikes are commonly used as defense structures for river flow channelization, protecting population and property from floods and against lateral riverbed migration. However, the aging of these structures ... [more ▼]

Dikes are commonly used as defense structures for river flow channelization, protecting population and property from floods and against lateral riverbed migration. However, the aging of these structures, combined with their increased vulnerability to extreme hydrological events may cause the dikes to breach, and subsequently to break. Furthermore, statistics show that flow overtopping is the main cause of dike failure, which emphasizes the need to understand thoroughly the process of breaching. Indeed, from a risk management perspective it is particularly important to have a detailed understanding of the mechanisms (e.g. internal erosion, overtopping erosion) underlying the formation of breaches due to overtopping and reliable information on flows passing through them. Conversely, the current knowledge of breaching mechanisms remains fragmented, especially because dike failure involves complex interactions between flows, materials of the structure, soil and foundations. The existing studies have addressed partially these interactions as the considered idealized dikes were generally homogenous, the piping erosion unaccounted for and the overtopping replicated in a dam-break like configuration. Yet, river embankments are subjected to high flow velocities parallel to the direction of the dike and to flow in the floodplain, which highly influence the shape of the breach and its evolution. The objective of the present work is to fill this gap. A laboratory experimental investigation is planned in the National Laboratory for Hydraulics and Environment (LNHE) of EDF R&D (France) and in the research group Hydraulics in Environmental and Civil Engineering (HECE) of the University of Liege (Belgium), reproducing realistic configurations of river dikes, accounting for the tangential flow in both main channel and floodplain. It enables thus the assessment of, on the one hand, the effect of the increase of the water level, and on the other hand, the influence of waves. The laboratory tests also consider the effect of a surface layer and composition of the dike core by testing different material mixtures. Geometry and composition of the idealized dikes are representative of typical field dikes, based on the similarity theory. [less ▲]

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See detailComposite hydraulic modeling to design a complex dam spillway
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

Conference (2015, July 01)

The paper presents the application of a composite hydraulic modeling approach to the rehabilitation studies of a complex dam spillway. First, a physical scale model of the existing works has been built ... [more ▼]

The paper presents the application of a composite hydraulic modeling approach to the rehabilitation studies of a complex dam spillway. First, a physical scale model of the existing works has been built and operated. It enabled to define very accurately the actual discharge capacity and to validate a numerical model of the system. Second, the numerical model has been used to rapidly test several rehabilitation solutions. Finally, the final design has been validated and optimized using the physical model. The paper shows how composite hydraulic modeling enables to combine the inherent advantages of physical and numerical modeling approaches, which are complementary, while being beneficial to the delay as well as the quality of the analysis. [less ▲]

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See detailImpacts of climate change on future flood damage on the river Meuse, with a distributed uncertainty analysis
Detrembleur, Sylvain; Stilmant, Frédéric ULg; Dewals, Benjamin ULg et al

in Natural Hazards (2015), 77(3), 1533-1549

Flood-risk assessments are an objective and quantitative basis for implementing harmonized flood mitigation policies at the basin scale. However, the generated results are subject to different sources of ... [more ▼]

Flood-risk assessments are an objective and quantitative basis for implementing harmonized flood mitigation policies at the basin scale. However, the generated results are subject to different sources of uncertainty arising from underlying assumptions, data availability and the random nature of the phenomenon. These sources of uncertainty are likely to bias conclusions because they are irregularly distributed in space. Therefore, this paper addresses the question of the influence of local features on the expected annual damage in different municipalities. Based on results generated in the frame of a transnational flood-risk-assessment project for the river Meuse (Western Europe) taking climate change into account, the paper presents an analysis of the relative contributions of different sources of uncertainty within one single administrative region (the Walloon region in Belgium, i.e. a river reach of approximately 150 km). The main sources of uncertainty are not only found to vary both from one municipality to the other and in time, but also to induce opposite effects on the computed damage. Nevertheless, practical conclusions for policy-makers can still be drawn. [less ▲]

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