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See detailInteractions between numerical and physical modelling for the design and optimization of hydraulic structures - Example of a large hydroelectric complex
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in Proceedings of the International Symposium on Hydraulic Structures, XXII Congreso Latinoamericano de Hidráhulica (2006)

This paper describes the successful combination of both physical and numerical modelling techniques applied to the scale model study of a large hydroelectric complex in India. Thanks to accurate numerical ... [more ▼]

This paper describes the successful combination of both physical and numerical modelling techniques applied to the scale model study of a large hydroelectric complex in India. Thanks to accurate numerical simulations, the physical model layout and the time to studies have been drastically reduced. First, prior to the design of the scale model, a global numerical simulation of the dam reservoir has been carried out, on the basis of the entire set of available topographic data. The simulation results supply the flow conditions in the upstream reservoir, particularly in the vicinity of the dam and the spillway crest. Subsequently, a second numerical computation has been performed to simulate the flow in a scale model representing only a small part of the reservoir upstream of the dam. The suitable correspondence between flow conditions in both cases has been demonstrated. This two-steps approach has enabled a significant reduction in the size of the scale model, and hence, a lower cost as well as a shorter delay for building the model. Simultaneously, it has been possible to decrease the scale factor at constant cost. In conclusion, the present paper provides convincing evidence that the increase in computers performance and the efficiency of contemporary free-surface flow solvers lead to useful numerical information for the optimal design and exploitation of scale models. [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 detailModern techniques for flood risk analysis: quasi-3D simulations in a GIS environment
Archambeau, Pierre ULg; Erpicum, Sébastien ULg; Dewals, Benjamin ULg et al

in Geophysical Research Abstracts (2005), 7(09348),

Human beings have continuously attempted to adapt their environment to their needs. However, many natural phenomena still remain challenging to control and the populations must undergo sometimes heavily ... [more ▼]

Human beings have continuously attempted to adapt their environment to their needs. However, many natural phenomena still remain challenging to control and the populations must undergo sometimes heavily damaging consequences. It is consequently essential to study these phenomena in order to assess their potential hazards. In particular, the scope of the present paper focus on floods. The intense floods met these last years showed the importance of this phenomenon as well as its many devastating effects. Thanks to recent important breakthroughs, both in the field of conceptual and numerical modelling of complex flows and in the calculation power of computers, it is henceforth possible to study the effects of potential floods on the basis of numerical simulations, with an accuracy never reached beforehand. The Laboratory of Applied Hydrodynamics and Hydraulic Constructions (HACH) of the University of Liege has always made this kind of study one of its core competencies, thanks to • the development of modern and powerful modelling tools (quasi-three dimensional software for flow simulation by finite volume), • the use of a broad range of data enabling a proper representation of the studied fields (topography, occupation of the ground...) • the systematic validation of simulation results. These tools are currently intensively used within the framework of a general study of the flood-prone zones of the Walloon area of Belgium, which corresponds to more than 800 km of rivers. [less ▲]

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See detailNumerical tools for the optimization of hydroelectric power stations in cascade
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in Dick, Erik; Hogge, Michel; Van Keer, Roger (Eds.) Proceedings of the 3rd Internationale Conference on Advanced Computational Methods in Engineering (2005)

The numerical optimization process of the system of hydroelectric power stations installed on a 60 km long section of the rivers Amblève and Warche in Belgium is presented in detail. The river network is ... [more ▼]

The numerical optimization process of the system of hydroelectric power stations installed on a 60 km long section of the rivers Amblève and Warche in Belgium is presented in detail. The river network is modelled in quasi-2D using real natural topographic data on almost 1,100 finite volumes. In a first step, the hydrological balance is closed using a numerical solver and roughness coefficients are calibrated from water level and discharge field measurements. Secondly, the hydroelectric production is maximised by an automatic calibration of the parameters of the hydrograph released in the network at the upstream dam. This approach leads to a substantial gain in hydroelectric production, brings significant financial benefits and deals with all management and security criteria of the river network. [less ▲]

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See detailOptimisation of hydroelectric power stations operations with WOLF package
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in Repp, K.; Westeren, T.; Sandlund, O. T. (Eds.) et al Proceedings of the 5th International Conference on Hydropower - The backbone of sustainable energy supply (2005)

For years, original free-surface flow solvers have been developed and continuously improved by the Laboratory of Applied Hydrodynamics and Hydraulic Constructions (HACH) at the University of Liège. The ... [more ▼]

For years, original free-surface flow solvers have been developed and continuously improved by the Laboratory of Applied Hydrodynamics and Hydraulic Constructions (HACH) at the University of Liège. The resulting fully integrated WOLF computation package allows engineers to accurately study a very wide range of various free surface flows, from hydrological runoff (WOLF HYDRO) and river propagation (WOLF 1D) to extreme erosive flows on realistic mobile topography (WOLF 2D), such as gradual dam breaching processes. All the finite volume models, process oriented, use efficient and original numerical methods to solve free surface flows equations. Each code handles general multiblock meshes, dealing with natural topography, dry and wet cells and mobile bed simultaneously, for any unsteady situation with mixed regimes and moving hydraulic jumps. The interactive and unique user-interface, with high performance pre- and post-processing, allows monitoring 3-D large-scale runs graphically while they proceed, as well as generating 3D videos. In addition, powerful optimisation capabilities based on the Genetic Algorithms technique (WOLF AG) are implemented within WOLF, interconnecting all the package components. An efficient tool is thus available to calibrate physical parameters in any of the models and to manage any problem of optimisation with the different solvers. In this paper, the numerical optimisation process of the system of hydroelectric power stations installed on a 60 km long section of the rivers Amblève and Warche in Belgium is presented in detail. The river network is modelled in quasi-2D using real natural topographic data on almost 1,100 finite volumes. In a first step, the hydrological balance is closed using the solver WOLF HYDRO. Roughness coefficients are calibrated from water level and discharge field measurements. Secondly, the hydroelectric production is maximised by an automatic calibration of the parameters of the hydrograph released in the network at the upstream dam. This approach leads to a substantial gain in hydroelectric production, brings significant financial benefits and deals with all management and security criteria of the river network. [less ▲]

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See detailModelling suspended load with moment equations and linear concentration profiles
Khuat Duy, Bruno ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Raghay, S.; Ouazar, D.; Benkhaldoun, F. (Eds.) Finite volumes for complex applications (2005)

In numerical simulations, it is always necessary to find an optimum between the simplicity of the model and a good representation of real phenomena. In the field of hydraulic flows simulations, the models ... [more ▼]

In numerical simulations, it is always necessary to find an optimum between the simplicity of the model and a good representation of real phenomena. In the field of hydraulic flows simulations, the models using depth-averaged and moment equations are an interesting compromise between full 3D and simple depth-averaged models. This paper presents the use of a moment equation for suspended load transport. A simple but representative model for the sediment concentration profiles is developed. This original bi-linear concentration profile is compared to the traditional Rouse-profiles and shows a good correspondence despite its great simplicity. Advective and diffusive sediment fluxes are developed analytically and lead to a concise formulation, which is an asset for practical use. A differential equation for the sediment concentration moment is also fully developed, and a special attention is cast to the source term. The finite volume scheme has been chosen to implement the model, because it is particularly well suited for highly advective transport equations, it is conservative and it makes the choice of the upwinding easier. 1D simulations show the capacity of the model to reproduce laboratory experiments described in the literature. [less ▲]

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See detailModelling suspended load transport with linear concentration profiles
Khuat Duy, Bruno ULg; Dewals, Benjamin ULg; Archambeau, Pierre ULg et al

in Proceedings of the 8th International Conference on Fluvial Sedimentology (2005)

In numerical simulations, it is always necessary to find an optimum between the simplicity of the model and a good representation of real phenomena. In the field of hydraulic flows simulations, the models ... [more ▼]

In numerical simulations, it is always necessary to find an optimum between the simplicity of the model and a good representation of real phenomena. In the field of hydraulic flows simulations, the models using depth-averaged and moment equations are an interesting compromise between full 3D and simple depth-averaged models. This paper presents the use of a moment equation for suspended load transport. A simple but representative model for the sediment concentration profiles is developed. This original bi-linear concentration profile is compared to the traditional Rouse-profiles and shows a good correspondence despite its great simplicity. Advective and diffusive sediment fluxes are developed analytically and lead to a concise formulation, which is an asset for practical use. A differential equation for the sediment concentration moment is also fully developed, and a special attention is cast to the source term. The finite volume scheme has been chosen to implement the model, because it is particularly well suited for highly advective transport equations, it is conservative and it makes the choice of the upwinding easier. 1D simulations show the capacity of the model to reproduce laboratory experiments described in the literature. [less ▲]

Detailed reference viewed: 39 (3 ULg)