References of "Journal of Hydraulic Research"
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See detailOptical flow estimation in aerated flows
Bung, Daniel B.; Valero Huerta, Daniel ULg

in Journal of Hydraulic Research (2016)

Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents ... [more ▼]

Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150. [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 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 detailDiscussion of "Two-dimensional depth-averaged finite volume model for unsteady turbulent flows"
Erpicum, Sébastien ULg; Pirotton, Michel ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (2014), 52(1), 148-150

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See detailExperimental parametric study and design of Piano Key Weirs
Machiels, Olivier; Pirotton, Michel ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (2014), 52(3), 326-335

Piano Key Weirs are an effective solution for dam rehabilitation as well as new dam projects with a high level of hydraulic constraints. In order to improve the efficiency of their design, an experimental ... [more ▼]

Piano Key Weirs are an effective solution for dam rehabilitation as well as new dam projects with a high level of hydraulic constraints. In order to improve the efficiency of their design, an experimental study of the influence of the main geometric parameters has been performed. Thirty one configurations were tested for a wide range of discharges. The results of the study show the influence of the weir height, the keys widths and the overhangs lengths on the discharge capacity and flow characteristics. Based on hydraulic considerations, optimum values of the main geometric ratios are provided. An analytical formulation is developed to predict the discharge capacity of the weir as a function of its geometry. It shows an accuracy of 10% compared to the experimental results of this study and from other sources. [less ▲]

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See detailPhysical modelling of water, fauna and flora: knowledge gaps, avenues for future research and infrastructural needs
ROBERT, THOMAS; JOHNSON, MATTHEW; FROSTICK, LYNNE et al

in Journal of Hydraulic Research (2014), 52

Physical modelling is a key tool for generating understanding of the complex interactions between aquatic organisms and hydraulics, which is important for management of aquatic environments under ... [more ▼]

Physical modelling is a key tool for generating understanding of the complex interactions between aquatic organisms and hydraulics, which is important for management of aquatic environments under environmental change and our ability to exploit ecosystem services. Many aspects of this field remain poorly understood and the use of physical models within eco-hydraulics requires advancement in methodological application and substantive understanding. This paper presents a review of the emergent themes from a workshop tasked with identifying the future infrastructure requirements of the next generation of eco-hydraulics researchers. The identified themes are: abiotic factors, adaptation, complexity and feedback, variation, and scale and scaling. The paper examines these themes and identifies how progress on each of them is key to existing and future eðorts to progress our knowledge of eco-hydraulic interactions. Examples are drawn from studies on biofilms, plants, and sessile and mobile fauna in shallow water fluvial and marine environments. Examples of research gaps and directions for educational, infrastructural and technological advance are also presented. [less ▲]

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See detailTurbulent non-uniform flows in straight compound open-channels
Proust, S.; Fernandes, J. N.; Peltier, Yann ULg et al

in Journal of Hydraulic Research (2013)

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See detailTurbulent flows in straight compound open-channel with a transverse embankment on the floodplain
Peltier, Yann ULg; Proust, S.; Rivière, N. et al

in Journal of Hydraulic Research (2013), 51(4), 446-458

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See detailCoupling between flow and sediment deposition in rectangular shallow reservoirs
Camnasio, Erica; Erpicum, Sébastien ULg; Orsi, Enrico et al

in Journal of Hydraulic Research (2013), 51(5), 535-547

Flow velocity and sedimentation patterns were investigated experimentally and numerically in shallow rectangular reservoirs with different asymmetric locations of the inlet and outlet channels. Velocity ... [more ▼]

Flow velocity and sedimentation patterns were investigated experimentally and numerically in shallow rectangular reservoirs with different asymmetric locations of the inlet and outlet channels. Velocity fields were measured in the entire reservoir, both for clear water flow and with suspended sediments. Thickness of sediment deposits were mapped in the whole reservoir by means of a laser light method. In one of the studied geometric configurations, injection of suspended sediments led to a complete change in the observed flow field. Experimental results were compared with numerical simulations performed with the depth-averaged flow model WOLF 2D, using a depth-averaged k-e turbulence model. The simulations lead to accurate predictions of the velocity profiles and the change in flow pattern as a result of sediment deposits was successfully reproduced. [less ▲]

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See detailThree‐phase Bi‐layer Model for Simulating Mixed Flows
Kerger, François ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in Journal of Hydraulic Research (2012), 50(3), 312-319

Mixed flows characterized by a simultaneous occurrence of free surface and pressurized flows are often encountered in hydraulic engineering. Numerous researches have been dedicated to unify the ... [more ▼]

Mixed flows characterized by a simultaneous occurrence of free surface and pressurized flows are often encountered in hydraulic engineering. Numerous researches have been dedicated to unify the mathematical description of both flows. Herein, shock-capturing models succeed in giving a unique set of equations. However, no method accounts for both air-entrapment and air-entrainment. This study proposes an original model to simulate air–water interactions in mixed flows. The new approach relies on the area-integration of a three-phase model over two layers. The applicability of this free surface model is extended to pressurized flows by a modified pressure term accounting for the dispersed air. The derived modelling system WOLF IMPack is then validated. The code successfully simulates open channel flows, mixed flows and water hammer in a unified framework, including air–water interactions, in structures like the drainage network. [less ▲]

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See detailDischarge coefficient for free and submerged flow over Piano Key Weirs - Discussion
Pfister, Michael; Erpicum, Sébastien ULg; Machiels, Olivier et al

in Journal of Hydraulic Research (2012), 50(6), 642-645

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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 detailExperimental observation of flow characteristics over a Piano Key Weir
Machiels, Olivier ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg et al

in Journal of Hydraulic Research (2011), 49(3), 359-366

The Piano Key Weir is a type of labyrinth weir using overhangs to reduce the foot print of the foundation. These are directly placed on a dam crest. Together with its high discharge capacity for low heads ... [more ▼]

The Piano Key Weir is a type of labyrinth weir using overhangs to reduce the foot print of the foundation. These are directly placed on a dam crest. Together with its high discharge capacity for low heads, this geometry makes these weirs interesting for dam rehabilitation. However, the Piano Key Weir is a new weir type, firstly designed in 2001 and built from 2006 by Electricité de France. Even if experimental studies confirmed its appealing discharge capacities, the flow upstream, over and downstream of this complex structure is still not well known. This research presents experimental test results performed on a 1:10 scale model. The experiments aim at determining the flow features along the weir depending on the upstream head. The flow conditions are characterized in terms of specific discharge, velocity, pressure, water level and streamlines along the weir. [less ▲]

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See detailClassification of flow patterns in rectangular shallow reservoirs
Dufresne, Matthieu; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

in Journal of Hydraulic Research (2010), 48(2), 197-204

This work focuses on the experimental classification of flow patterns in rectangular shallow reservoirs, including symmetric flows without any reattachment point to asymmetric flows with one reattachment ... [more ▼]

This work focuses on the experimental classification of flow patterns in rectangular shallow reservoirs, including symmetric flows without any reattachment point to asymmetric flows with one reattachment point, two reattachment points, or two reattachment points and one detachment point. The median position and the natural variability of the reattachment lengths of asymmetric flows were measured for forty geometric and hydraulic conditions. The effects of dimensionless flow depth, Froude number, lateral expansion ratio and dimensionless length on the median reattachment lengths were analyzed. A number of regression equations were proposed. For “high” dimensionless flow depths and a Froude number of 0.20, a shape parameter was proposed for predicting the transition between symmetric and asymmetric flows. The results of this study are useful knowledge for improving current methods to predict the trapping efficiency and the preferential regions of deposition in reservoirs. [less ▲]

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See detailExperimental and numerical investigations of dike-break induced flows
Roger, Sebastian; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

in Journal of Hydraulic Research (2009), 47(3), 349-359

Experimental model data are compared with numerical computations of dike-break induced flows, focusing on the final steady state. An idealised scale model was designed reproducing the specific boundary ... [more ▼]

Experimental model data are compared with numerical computations of dike-break induced flows, focusing on the final steady state. An idealised scale model was designed reproducing the specific boundary conditions of dike breaks. Discharges, water levels and depth profiles of horizontal velocities were recorded and validated by numerical modeling. The latter was performed by two different models solving the two-dimensional depth-averaged shallow water equations, namely a total variation diminishing Runge-Kutta dis¬continuous Galerkin finite element method, and a finite volume scheme involving a flux vector splitting ap¬proach. The results confirmed convergence and general applicability of both methods for dike-break prob¬lems. As regards their accuracy, the basic flow pattern was satisfactorily reproduced yet with differences compared to the measurements. Hence, additional simulations by a finite volume model were performed con¬sidering various turbulence closures, wall-roughnesses as well as non-uniform Boussinesq coefficients. [less ▲]

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See detailDepth-integrated flow modelling taking into account bottom curvature
Dewals, Benjamin ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (2006), 44(6), 787-795

Successfully modelling flows over a spillway and on strongly vertically curved bottoms is a challenge for any depth-integrated model. This type of computation requires the use of axes properly inclined ... [more ▼]

Successfully modelling flows over a spillway and on strongly vertically curved bottoms is a challenge for any depth-integrated model. This type of computation requires the use of axes properly inclined along the mean flow direction in the vertical plane and a modelling of curvature effects. The proposed generalized model per-forms such computations by means of suitable curvilinear coordinates in the vertical plane, leading to a fully integrated approach. This means that the flows in the upstream reservoir, on the spillway, in the stilling basin and in the downstream river reach are all handled in a single simulation. The velocity profile is generalized in comparison with the uniform one usually assumed in the classical shallow water equations. The pressure dis-tribution is modified as a function of the bottom curvature and is thus not purely hydrostatic. Representative test cases, as well as the application of the extended model to the design of a large hydraulic structure in Bel-gium, lead to satisfactory validation results. [less ▲]

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See detailThermohydrodynamical modelling of a power plant implementation in the Zeebrugge harbour
Beckers, Jean-Marie ULg; Vanormelingen, J.-J.

in Journal of Hydraulic Research (1995), 33(2), 163-180

A mathematical model and numerical simulation has been used to test the validity of a water and thermal circulation scheme induced by the implementation of a new power plant in the Zeebrugge harbour. The ... [more ▼]

A mathematical model and numerical simulation has been used to test the validity of a water and thermal circulation scheme induced by the implementation of a new power plant in the Zeebrugge harbour. The aim of the study was to: a) verify that in the interior basin of the inner harbour, a sufficient stratification is present to allow for the capture of cold bottom waters, whereas the ejected heated water remains at the surface and is evacuated to the main harbour, b) study the way the water cools in the main harbour and to quantify the amount of thermal energy which is pumped back into the inner harbour, c) determine if the global heat excess is evacuated and if the resulting temperature increase remains within reasonable limits at the power plant pump inlet. The study, accomplished in three steps, determined the parameters that control the recirculation (e.g. atmospheric conditions) and what their relative importance is. It was shown that a stratification is created in the interior basin. In the main harbour the heat evacuation is done primarily by evaporation in the harbour and only for 20% by the outflow to the open sea. Extreme temperature increases at the pump inlet are expected to be 1.6 degrees C and 6.6 degrees C,but generally the temperature increase lies between 3-4 degrees C. The actual value was found to be most sensitive to the atmospheric conditions. [less ▲]

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