27 results on '"Riadh Ata"'
Search Results
2. Use of Large-Eddy Simulation for the bed shear stress estimation over a dune
- Author
-
Adrien Bourgoin, Riadh Ata, Jérôme Thiébot, and Sylvain Guillou
- Subjects
Turbulence ,business.industry ,Stratigraphy ,Flow (psychology) ,0207 environmental engineering ,Geology ,02 engineering and technology ,Mechanics ,010501 environmental sciences ,Computational fluid dynamics ,01 natural sciences ,Free surface ,Shear stress ,020701 environmental engineering ,business ,Reynolds-averaged Navier–Stokes equations ,Sediment transport ,0105 earth and related environmental sciences ,Large eddy simulation - Abstract
Environmental flows are generally characterized by complex bed morphology and high current speeds. Such configurations favor the formation of vortex structures that strongly affect hydrody-namics and sediment transport. Large-Eddy Simulation (LES) enables investigation of the dynam-ics of the largest turbulence scales and, thanks to enhanced calculation resources, has now become applicable for simulating environmental flows. In this paper, a LES approach is developed in a CFD code (TELEMAC-3D), which was originally developed to simulate free surface flows using RANS methods. The present developments involve implementing subgrid models, boundary con-ditions and numerical schemes suitable for LES. The LES version of TELEMAC-3D was validated by comparing results on the model with experimental data for flow past a cylinder. Then, the model was applied to a test case representing flow over dunes. After validating the hydrodynamics, the model was used to assess the bottom shear stress, using both a RANS and a LES approach. Com-parison highlighted the potential contribution of LES to investigating the hydrodynamic forces acting on the bottom.
- Published
- 2021
3. An adoption of the Spalart–Allmaras turbulence model for two- and three-dimensional free surface environmental flows
- Author
-
Sofiane Benhamadouche, Adrien Bourgoin, Riadh Ata, and Kamal El Kadi Abderrezzak
- Subjects
Physics ,Spalart–Allmaras turbulence model ,Turbulence ,0208 environmental biotechnology ,Mode (statistics) ,02 engineering and technology ,Mechanics ,01 natural sciences ,010305 fluids & plasmas ,020801 environmental engineering ,Physics::Fluid Dynamics ,Free surface ,0103 physical sciences ,Compressibility ,Navier–Stokes equations ,Shallow water equations ,Water Science and Technology ,Civil and Structural Engineering - Abstract
In this paper, the Spalart–Allmaras turbulence model, very popular for compressible aerospace applications, is adapted for incompressible free surface environmental flows. The Spalart–Allmaras mode...
- Published
- 2020
4. Investigating the turbidity current venting operation from multiple outlets by using TELEMAC-3D
- Author
-
Peng An CHEN, Sameh A. KANTOUSH, Tetsuya SUMI, Doan Van BINH, Sebastien E. BOURBAN, and Riadh ATA
- Published
- 2022
5. Hydrodynamics, sediment transport, and morphodynamics in the Vietnamese Mekong Delta: Field study and numerical modelling
- Author
-
Doan Van Binh, Sameh A. Kantoush, Riadh Ata, Pablo Tassi, Tam V. Nguyen, Jérémy Lepesqueur, Kamal El Kadi Abderrezzak, Sébastien E. Bourban, Quoc Hung Nguyen, Doan Nguyen Luyen Phuong, La Vinh Trung, Dang An Tran, Thanh Letrung, and Tetsuya Sumi
- Subjects
Earth-Surface Processes - Published
- 2022
6. Determination of monochloramine dissipation kinetics in various surface water qualities under relevant environmental conditions - Consequences regarding environmental risk assessment
- Author
-
Bertille Richard-Tanaka, Adrien Roumiguières, Aziz Kinani, Michael Merklinger, Franck Marolleau, Said Kinani, Pia Gerstner, Stephany Layousse, Astrid Thoma, Riadh Ata, Stéphane Bouchonnet, Frank Sacher, DVGW-Technologiezentrum Wasser (TZW), Deutsche Verein des Gas- und Wasserfaches (DVGW), Laboratoire National d’Hydraulique et Environnement (EDF R&D LNHE), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Laboratoire de chimie moléculaire (LCM), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)
- Subjects
Environmental Engineering ,010504 meteorology & atmospheric sciences ,Lag ,Kinetics ,Extrapolation ,Sampling (statistics) ,Sediment ,010501 environmental sciences ,Dissipation ,01 natural sciences ,Pollution ,6. Clean water ,13. Climate action ,Environmental chemistry ,Environmental Chemistry ,Degradation (geology) ,Environmental science ,[CHIM.OTHE]Chemical Sciences/Other ,Waste Management and Disposal ,Surface water ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
A total 190 experiments were performed to study the dissipation kinetics of monochloramine (NH2Cl, CAS no 10599-90-3) in surface water samples from six rivers (Loire, Rhone, Meuse, Garonne, Seine and Moselle) and an artificial reservoir (Mirgenbach), all located in France. Experiments were conducted in an open reactor, under relevant controlled environmental conditions. The impact of various parameters such as initial NH2Cl concentration, temperature, pH, presence of sediments, sampling site and collection period was investigated. It was found that NH2Cl dissipated rapidly without any lag phase, and that decay follows an apparent first-order kinetics (r2 > 0.99). Presence of sediment greatly accelerated decay. Half-lives were generally
- Published
- 2019
7. Depth averaged numerical simulation of non-cohesive river dike breaching due to overtopping flows
- Author
-
Riadh Ata, Benjamin Dewals, K. El Kadi Abderrazzak, Ismail Rifai, and L. Kheloui
- Subjects
Dike ,geography ,geography.geographical_feature_category ,Computer simulation ,Depth averaged ,Geotechnical engineering ,Geology - Published
- 2020
8. Turbulence characterization at a tidal energy site using large-eddy simulations: case of the Alderney Race
- Author
-
Adrien Bourgoin, Riadh Ata, Jérôme Thiébot, and Sylvain Guillou
- Subjects
business.industry ,Turbulence ,General Mathematics ,General Engineering ,General Physics and Astronomy ,Geophysics ,Articles ,Vortex ,Characterization (materials science) ,Current (stream) ,Physics::Fluid Dynamics ,business ,Tidal power ,Seabed ,Geology ,Large eddy simulation - Abstract
Sites suitable for the deployment of tidal turbines generally show a combination of complex seabed morphologies and extreme current magnitudes. Such configurations favour the formation of vortices, which can be very powerful. Anticipating the vortex effect on the turbine performance and/or lifespan requires refined description of the turbulence. Thanks to increased calculation resources, large-eddy simulation (LES) can now be applied to natural flow. An LES approach developed within the TELEMAC-3D open-source software is presented here. After validating the model with in-situ measurements, the model is applied to characterize the flow statistics of the Alderney Race. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.
- Published
- 2020
9. Experimental and 2D Numerical Modelling of Morphology and Bank Erosion in Meandering Channels of Different Sinuosity
- Author
-
Riadh Ata, Saroj Karki, Karki Nakagawa, El Kadi Abderrezzak, Yuji Hasegawa, Pablo Tassi, Kamal, Masakazu Hashimoto, Kenji Kawaike, and Eddy J. Langendoen
- Subjects
Morphology (linguistics) ,Sinuosity ,Geomorphology ,Geology ,Bank erosion - Published
- 2019
10. La Palma landslide tsunami: computation of the tsunami source with a calibrated multi-fluid Navier–Stokes model and wave impact assessment with propagation models of different types
- Author
-
Riadh Ata, Rodrigo Pedreros, Lucie Clous, Jeffrey C. Harris, Sylvestre Le Roy, Philippe Heinrich, Stéphane Abadie, Yann Krien, Gael Arnaud, Adrien Poupardin, and Alexandre Paris
- Subjects
Viscosity ,Amplitude ,Time of arrival ,Impact assessment ,Computation ,Newtonian fluid ,Landslide ,Navier stokes ,Geodesy ,Geology - Abstract
In this paper, we present a new source assessment of the La Palma collapse scenario previously described and studied in Abadie et al. (2012). Three scenarios (i.e., slide volumes of 20, 40 and 80 km3) are considered, from the initiation of the slide to the water waves generation, using THETIS, a 3D Navier–Stokes model. The slide is considered as a Newtonian fluid whose viscosity is adjusted to approximate a granular behavior. After 5 minutes of propagation with THETIS, the generated water wave is transferred into FUNWAVE-TVD for 15 minutes of Boussinesq model simulation. Then, four different depth-averaged codes are used to propagate the wave to the Guadeloupe area, Europe and French coasts. Finally, the wave impact in terms of run-up is evaluated through direct computations in specific areas or using theoretical formulas. Although the wave source appears reduced due to the rheology used compared to former works, the wave impact is still significant for the maximum slide volume considered on surrounding islands and coasts, as well as on remote most exposed coasts such as Guadeloupe. In Europe and in France, the wave impact is moderate (for specific areas in Spain and Portugal) to weak (Atlantic French coast). The comparison between the different wave models in overlapping computational regions shows an overall agreement in terms of first wave amplitude and time of arrival, but differences appear in the trailing waves.
- Published
- 2019
11. Shape Optimization of Hydraulic Structures: an Example of an Optimum Design of a Fish Passage
- Author
-
Cédric Goeury, Fabrice Zaoui, Riadh Ata, Pat Prodanovic, Jacques Fontaine, Yoann Audouin, and Pablo Tassi
- Subjects
Hydraulic structure ,Computer science ,%22">Fish ,Shape optimization ,Marine engineering - Abstract
This paper presents a practical methodology developed for shape optimization studies of hydraulic structures using environmental numerical modelling codes. The methodology starts by defining the optimization problem and identifying relevant problem constraints. Design variables in shape optimization studies are configuration of structures (such as length or spacing of groins, orientation and layout of breakwaters, etc.) whose optimal orientation is not known a priori. The optimization problem is solved numerically by coupling an optimization algorithm to a numerical model. The coupled system is able to define, test and evaluate a multitude of new shapes, which are internally generated and then simulated using a numerical model. The developed methodology is tested using an example of an optimum design of a fish passage, where the design variables are the length and the position of slots. In this paper an objective function is defined where a target is specified and the numerical optimizer is asked to retrieve the target solution. Such a definition of the objective function is used to validate the developed tool chain. This work uses the numerical model TELEMAC- 2Dfrom the TELEMAC-MASCARET suite of numerical solvers for the solution of shallow water equations, coupled with various numerical optimization algorithms available in the literature.
- Published
- 2018
12. Shallow water numerical models for the 1947 gisborne and 2011 Tohoku-Oki tsunamis with kinematic seismic generation
- Author
-
Xiaoming Wang, Riadh Ata, Damien Violeau, Marine Le Gal, and Violeau, Damien
- Subjects
Environmental Engineering ,010504 meteorology & atmospheric sciences ,Initialization ,Ocean Engineering ,Kinematics ,Deformation (meteorology) ,010502 geochemistry & geophysics ,01 natural sciences ,Physics::Geophysics ,Waves and shallow water ,Nonlinear system ,Amplitude ,Free surface ,[PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] ,Seabed ,Geology ,Seismology ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
Traditionally, the initialization of seismically generated tsunamis is done by setting the initial free surface deformation as identical to the final deformation of the sea floor. However, numerous effects are neglected through this method, in particular the dynamics of the sea floor deformation. Here, two temporal parameters characterizing the sea floor deformation are defined: the rise time tr (vertical motion) and the rupture velocity Vp (horizontal motion). These parameters have already been theoretically introduced by Hammack (1973) and Todorovska and Trifunac (2001), respectively. For a simplified and schematic motion of the sea floor using simultaneously both parameters, a theoretical linear analysis developed in Le Gal et al. (2017) showed a resonance phenomenon for which the amplitude of the generated wave becomes significantly larger than the amplitude of the sea floor deformation. This phenomenon concerns deformation with small rise times and rupture velocities close to the linear long wave velocity g h . The aim of the present study is to investigate the influence of a kinematic deformation, using both parameters, during historical tsunamis with numerical nonlinear shallow water simulations. This work corroborates Le Gal et al.’s theoretical schematic analysis. For this purpose, two events are studied: the March 1947 New Zealand and the 2011 Japan tsunamis.
- Published
- 2018
13. Multiphase smoothed particle hydrodynamics approach for modeling soil–water interactions
- Author
-
Mehdi Rezoug, Sofiane Khelladi, Abdelkader Krimi, Michael Deligant, Riadh Ata, Xesús Nogueira, Laboratoire de Dynamique des Fluides (DynFluid), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), University of A Coruña (UDC), Laboratoire de Mécanique des Systèmes et des Procédés (LMSP), Centre National de la Recherche Scientifique (CNRS), Ecole de Technologie Supérieure [Montréal] (ETS), Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics (Saint-Venant), École des Ponts ParisTech (ENPC)-Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Laboratoire National d’Hydraulique et Environnement (EDF R&D LNHE), EDF R&D (EDF R&D), Institut de Recherche en Constructibilité (IRC), and École Spéciale des Travaux Publics, du Bâtiment et de l'Industrie [Paris] (ESTP )-Communauté Université Paris-Est
- Subjects
Work (thermodynamics) ,0208 environmental biotechnology ,Constitutive equation ,Soil-water interactions ,Smoothed particle hydrodynamics method ,Multiphase fluid flow ,Failure criteria ,Non-Newtonian fluid ,02 engineering and technology ,01 natural sciences ,Compressible flow ,010305 fluids & plasmas ,[SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] ,Smoothed-particle hydrodynamics ,Physics::Fluid Dynamics ,Rheology ,0103 physical sciences ,Water Science and Technology ,Physics ,Mechanics ,020801 environmental engineering ,Compressibility ,Bingham plastic ,Mécanique: Mécanique des fluides [Sciences de l'ingénieur] - Abstract
International audience; In this work, a weakly compressible smoothed particle hydrodynamics (WCSPH) multiphase model is developed. The model is able to deal with soil-water interactions coupled in a strong and natural form. A Regularized Bingham Plastic constitutive law including a pressure-dependent Mohr-Coulomb yield criterion (RBPMC-αμ) is proposed to model fluids, soils and their interaction. Since the proposed rheology model is pressure-sensitive, we propose a multiphase diffusive term to reduce the spurious pressure resulting from the weakly compressible flow hypothesis. Several numerical benchmarks are investigated to assess the robustness and accuracy of the proposed multiphase SPH model.
- Published
- 2018
14. One-dimensional numerical modelling of solute transport in streams: The role of longitudinal dispersion coefficient
- Author
-
Kamal El Kadi Abderrezzak, Riadh Ata, Fabrice Zaoui, Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics (Saint-Venant), École des Ponts ParisTech (ENPC)-Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Simulation et Traitement de l'information pour l'Exploitation des systèmes de Production (EDF R&D STEP), and EDF R&D (EDF R&D)
- Subjects
Work (thermodynamics) ,Rank (linear algebra) ,Field (physics) ,Mechanics ,STREAMS ,Dispersion coefficient ,Variable flow ,[SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] ,Flow (mathematics) ,[SDE]Environmental Sciences ,Statistics ,Range (statistics) ,ComputingMilieux_MISCELLANEOUS ,Water Science and Technology ,Mathematics - Abstract
One-dimensional (1-D) numerical models of solute transport in streams rely on the advection–dispersion equation, in which the longitudinal dispersion coefficient is an unknown parameter to be calibrated. In this work we investigate the extent to which existing empirical formulations of longitudinal dispersion coefficient can be used in 1-D numerical modelling tools of solute transport under steady and unsteady flow conditions. The 1-D numerical model used here is the open source Mascaret tool. Its relevance is illustrated by simulating theoretical cases with known analytical solutions. Ten empirical formulas of longitudinal dispersion coefficient are then tested by simulating eight laboratory experimental cases under steady flow condition and the solute transport in the Middle Loire River (350 km long) under highly variable flow condition (from July 1st 1999 to December 31st 1999). Comparisons between computed and measured breakthrough curves show that Elder (1959), Fischer (1975) and Iwasa and Aya (1991) formulas rank as the best predictors for the experimental cases. For the field case, Seo and Cheong’s (1998) formula yields the best model-data agreement, followed by Iwasa and Aya’s (1991) formula. The latter formula is, therefore, recommended for the entire range of conditions studied here.
- Published
- 2015
15. Uncertainty quantification for river flow simulation applied to a real test case: the Garonne valley
- Author
-
Hind Oubanas, Riadh Ata, Cédric Goeury, Igor Yu. Gejadze, Sophie Ricci, Nabil El Moçayd, Pierre-Olivier Malaterre, Mélanie C. Rochoux, Nicole Goutal, EDF (EDF), Centre National de la Recherche Scientifique (CNRS), Gestion de l'Eau, Acteurs, Usages (UMR G-EAU), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-AgroParisTech-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)
- Subjects
VARIATIONAL METHOD ,State variable ,SHALLOW WATER EQUATIONS ,Automatic differentiation ,0208 environmental biotechnology ,Context (language use) ,LOCAL AND GLOBAL SENSITIVITY ANALYSIS ,010103 numerical & computational mathematics ,02 engineering and technology ,01 natural sciences ,Control theory ,AUTOMATIC DIFFERENTIATION ,Sensitivity (control systems) ,POLYNOMIAL CHAOS ,0101 mathematics ,Uncertainty quantification ,VARIANCE DECOMPOSITION ,Polynomial chaos ,Direct method ,6. Clean water ,020801 environmental engineering ,TELEMAC ,SALTELLI METHOD ,[SDE]Environmental Sciences ,Environmental science ,TAPENADE SOFTWARE - Abstract
International audience; Sensitivity analysis techniques have been widely used in multitude of applications to quantify the impact of inputs variables imprecision on the accuracy of the model output variables. Depending on the problem at hand, an appropriate method of sensitivity analysis should be selected. Direct and adjoint sensitivity analysis are two complementary approaches known to be efficient. While the direct approach provides an assessment of the propagation of the error of a given input parameter in the studied system, the adjoint approach enables to identify the source of the uncertainty of a given output variable with respect to several input parameters. Direct methods have been extensively investigated in different geophysical applications, particularly in the context of the hydraulic modeling. In this work, several methods will be described and applied to the same benchmark during over-flooding events. The effect of uncertainties in the boundary conditions, the spatially distributed functions (bed level, river width, friction, etc.) and the numerical parameters on the model state variables (discharge, water surface elevation, etc.) is examined. This study has been carried out on the Garonne River test case, along a 50 km downstream reach, using 1D full Saint-Venant hydraulic models SIC2 (Irstea) or Mascaret (EDF), and 2D Telemac model (EDF). Results illustrate the influence of individual and combined contributions of input variables uncertainties.
- Published
- 2017
16. Numerical assessment of the interactions between hydrodynamics, bed morphodynamics and bank erosion
- Author
-
Riadh Ata, Jorge D. Abad, K. El, A. Mendoza, Eddy J. Langendoen, Kadi Abderrezzak, Mick Ursic, and Pablo Tassi
- Subjects
Geotechnical engineering ,Numerical assessment ,Geology ,Bank erosion ,Beach morphodynamics - Published
- 2016
17. Towards a turbulence characterization in tidal energy sites. First results of THYMOTE project
- Author
-
Adrien Bourgoin, Nicolas Chaplain, Aline Pieterse, Jérôme Laverne, Christophe Maisondieu, Emmanuel Poizot, Sylvain Guillou, Rui Duart, Riadh Ata, Grégory Pinon, Philippe Mercier, Benoît Gaurier, Elois Droniou, Maria Ikheunnicheu, Jean-François Filipot, Grégory Germain, Jérôme Thiébot, Sofiane Benhamadouche, Valentin Arramounet, Cédric Auvray, Jean-Charles Poirier, Laboratoire Universitaire des Sciences Appliquées de Cherbourg (LUSAC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), France Energies Marines [Brest], Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Chercheur indépendant, Laboratoire National d’Hydraulique et Environnement (EDF R&D LNHE), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Laboratoire Ondes et Milieux Complexes (LOMC), and Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH)
- Subjects
Field (physics) ,business.industry ,Turbulence ,0211 other engineering and technologies ,02 engineering and technology ,Geophysics ,Physical modelling ,Characterization (materials science) ,Physics::Fluid Dynamics ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Eddy ,lcsh:TA1-2040 ,Free surface ,021105 building & construction ,[PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] ,High current ,lcsh:Engineering (General). Civil engineering (General) ,business ,Tidal power - Abstract
International audience; Tidal turbine will be installed in area with high current and high turbulence level. A characterisation of this last is required. The aim of the project THYMOTE is to characterize and understand the generation of eddies from smaller to several tens of meters. Three technics are used: Numerical modelling, Physical modelling, field measurements. Physical and numerical modelling show clearly the appearance of the eddies close to the bottom in presence of dunes or rocks and their motion towards the free surface.
- Published
- 2019
18. A Weighted Average Flux (WAF) scheme applied to shallow water equations for real-life applications
- Author
-
Eleuterio F. Toro, Riadh Ata, Sofiane Khelladi, and Sara Pavan
- Subjects
symbols.namesake ,TELEMAC ,Finite volume method ,Discretization ,Mathematical analysis ,symbols ,Order of accuracy ,Numerical diffusion ,Shallow water equations ,Conservation of mass ,Riemann solver ,Water Science and Technology ,Mathematics - Abstract
This work focuses on the application of a Weighted Average Flux (WAF) approximation to the shallow water equations with friction and real bathymetry on unstructured two dimensional grids. The scheme obtained must satisfy severe numerical criteria so it can be implemented in the TELEMAC code, widely used in industry. Despite its interesting numerical properties (at least in theory, which includes second order in time and space), WAF approximation is rarely applied to unstructured meshes. Here, we provide a general method for applying the WAF scheme to a homogenous equation. The general and efficient discretization of the topographic source term (through hydrostatic reconstruction) and friction (with a semi-implicit way) is also presented. We applied the approximation using the HLLC Riemann solver within a vertex-centered finite volume framework. The discretization obtained is validated with several theoretical and real benchmarks. The WAF-HLLC scheme proposed is also compared to several other well-known schemes such as HLLC, Roe and Kinetic type schemes. The results obtained show that the behavior of the scheme is encouraging as they demonstrate well-balanceness, strict mass conservation, positivity of water depth, efficient treatment of wetting and drying phenomena, good shock-capturing and low numerical diffusion. Nevertheless, the second order of accuracy in space is not attained with sufficient rigor and remains an open problem requiring more detailed study.
- Published
- 2013
19. Modelling river bank erosion using a 2D depth-averaged numerical model of flow and non-cohesive, non-uniform sediment transport
- Author
-
Pablo Tassi, Riadh Ata, Jean-Michel Hervouet, Kamal El Kadi Abderrezzak, Andres Die Moran, Simulation et Traitement de l'information pour l'Exploitation des systèmes de Production (EDF R&D STEP), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics (Saint-Venant), École des Ponts ParisTech (ENPC)-Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema)-EDF R&D (EDF R&D), Laboratoire National d’Hydraulique et Environnement (EDF R&D LNHE), Laboratoire d'Hydraulique Saint-Venant / Saint-Venant Laboratory for Hydraulics (Saint-Venant), and École des Ponts ParisTech (ENPC)-PRES Université Paris-Est-EDF (EDF)-Avant création Cerema
- Subjects
Engineering ,business.industry ,0208 environmental biotechnology ,[INFO.INFO-CE]Computer Science [cs]/Computational Engineering, Finance, and Science [cs.CE] ,02 engineering and technology ,6. Clean water ,Angle of repose ,020801 environmental engineering ,Unstructured grid ,Flume ,Cohesion (geology) ,Geotechnical engineering ,business ,Bank failure ,Scale model ,Sediment transport ,Bank erosion ,ComputingMilieux_MISCELLANEOUS ,Water Science and Technology - Abstract
Bank erosion can be an important form of morphological adjustment in rivers. With the advances made in computational techniques, two-dimensional (2D) depth-averaged numerical models have become valuable tools for resolving many engineering problems dealing with sediment transport. The objective of this research work is to present a simple, new, bank-erosion operator that is integrated into a 2D Saint-Venant-Exner morphodynamic model. The numerical code is based on an unstructured grid of triangular elements and finite-element algorithms. The slope of each element in the grid is compared to the angle of repose of the bank material. Elements for which the slope is too steep are tilted to bring them to the angle of repose along a horizontal axis defined such that the volume loss above the axis is equal to the volume gain below, thus ensuring mass balance. The model performance is assessed using data from laboratory flume experiments and a scale model of the Old Rhine. For the flume experiment case with uniform bank material, relevant results are obtained for bank geometry changes. For the more challenging case (i.e. scale model of the Old Rhine with non-uniform bank material), the numerical model is capable of reproducing the main features of the bank failure, induced by the newly designed groynes, as well as the transport of the mobilized sediment material downstream. Some deviations between the computed results and measured data are, however, observed. They are ascribed to the effects of three-dimensional (3D) flow structures, pore pressure and cohesion, which are not considered in the present 2D model.
- Published
- 2016
20. A multi-temporal analysis of AMSR-E data for flood and discharge monitoring during the 2008 flood in Iowa
- Author
-
Hosni Ghedira, Riadh Ata, Marouane Temimi, Reza Khanbilvardi, Tarendra Lakhankar, Teodosio Lacava, and Valerio Tramutoli
- Subjects
Radiometer ,Meteorology ,Flood myth ,Discharge ,Streamflow ,Environmental science ,Satellite imagery ,Rating curve ,Time of concentration ,Change detection ,Water Science and Technology ,Remote sensing - Abstract
The objective of this work is to demonstrate the potential of using passive microwave data to monitor flood and discharge conditions and to infer watershed hydraulic and hydrologic parameters. The case study is the major flood in Iowa in summer 2008. A new Polarisation Ratio Variation Index (PRVI) was developed based on a multi-temporal analysis of 37 GHz satellite imagery from the Advanced Microwave Scanning Radiometer (AMSR-E) to calculate and detect anomalies in soil moisture and/or inundated areas. The Robust Satellite Technique (RST) which is a change detection approach based on the analysis of historical satellite records was adopted. A rating curve has been developed to assess the relationship between PRVI values and discharge observations downstream. A time-lag term has been introduced and adjusted to account for the changing delay between PRVI and streamflow. Moreover, the Kalman filter has been used to update the rating curve parameters in near real time. The temporal variability of the b exponent in the rating curve formula shows that it converges toward a constant value. A consistent 21-day time lag, very close to an estimate of the time of concentration, was obtained. The agreement between observed discharge downstream and estimated discharge with and without parameters adjustment was 65 and 95%, respectively. This demonstrates the interesting role that passive microwave can play in monitoring flooding and wetness conditions and estimating key hydrologic parameters. Copyright © 2011 John Wiley & Sons, Ltd.
- Published
- 2011
21. Numerical study on reservoir sediment management through adding excavated sediment downstream of dams in Japan
- Author
-
Kamal El Kadi Abderrezzak, Riadh Ata, Yasuhiro Takemon, Mohamed Saber, Tetsuya Sumi, Sameh A. Kantoush, and Takamasa Suzuki
- Subjects
lcsh:GE1-350 ,Hydrology ,geography ,geography.geographical_feature_category ,Downstream (manufacturing) ,Shoal ,Environmental science ,Sediment ,Sedimentation ,Turbidity ,reproductive and urinary physiology ,lcsh:Environmental sciences - Abstract
Dam related issues have become preoccupying, with raising concerns about detrimental environmental impacts and sedimentation in reservoirs. Reduction of the Ayu-fish production is due to increasing turbidity and decreasing coarse sediment supply by dams in the Tenryu River, Japan. The paper summarizes various case studies on excavated sediment supply in Japan and a case of numerical study to evaluate the effect of the supplied sediment on the spawning redds of Ayu-fish in the Tenryu River. Results of numerical simulations show that under the present management scheme of non-supplied sediment from the upstream dams, suitable spawning redds are formed on sandbars at the confluence instead of riffles. However, field surveys indicate that riffles with newly deposited sediment are more suitable for fish spawning.
- Published
- 2018
22. A stabilized SPH method for inviscid shallow water flows
- Author
-
Azzeddine Soulaïmani and Riadh Ata
- Subjects
Standard form ,Applied Mathematics ,Mechanical Engineering ,Mathematical analysis ,Computational Mechanics ,Geometry ,Stability (probability) ,Riemann solver ,Computer Science Applications ,Smoothed-particle hydrodynamics ,Waves and shallow water ,symbols.namesake ,Mechanics of Materials ,Inviscid flow ,symbols ,Shallow water equations ,Interpolation ,Mathematics - Abstract
The smoothed particle hydrodynamics (SPH) method is applied to the solution of shallow water equations. A brief review of the method in its standard form is first described then a variational formulation using SPH interpolation is discussed. A new technique based on the Riemann solver is introduced to improve the stability of the method
- Published
- 2004
23. Variational Data Assimilation with TELEMAC. Proof of Concept for Model State Correction on the Berre Lagoon 3D-Model
- Author
-
Nicole Goutal, Andrea Piacentini, Sophie Ricci, Anthony T. Weaver, and Riadh Ata
- Subjects
Physics ,Meteorology ,Hydraulics ,Flow (psychology) ,Physics::Geophysics ,law.invention ,TELEMAC ,Data assimilation ,law ,Proof of concept ,Bathymetry ,Boundary value problem ,Representation (mathematics) ,Physics::Atmospheric and Oceanic Physics - Abstract
TELEMAC is a component of the open-source integrated suite of solvers TELEMAC-MASCARET for use in the field of free-surface flow that solves the Reynolds Averaged Navier-Stokes equations. Generally speaking, uncertainties in the model formulation itself due to simplified physics and also in the input fields to the model such as the boundary conditions, initial conditions and hydraulic parameters translate into errors in the simulated hydraulic variables. In spite of significant advances in numerical schemes, description of geographical data (topography, bathymetry) and environmental conditions (hydrologycal and meteorological fields), the representation of the true state of a system as well as its forecasted state remains imperfect and some of these limits can be overcome combining observations with simulation via data assimilation techniques. This paper presents the implementation of a 3D-Var FGAT variational data assimilation algorithm as a proof of concept for improving TELEMAC simulations and forecast. The demonstration is made on the Berre lagoon application with TELEMAC-3D: the salinity state is sequentially corrected assimilating in situ salinity measurements.
- Published
- 2014
24. Estimation of Lateral Inflows Using Data Assimilation in the Context of Real-Time Flood Forecasting for the Marne Catchment in France
- Author
-
Sophie Ricci, Fabrice Zaoui, G. Jonville, Andrea Piacentini, Olivier Thual, Riadh Ata, Etienne Le Pape, Johan Habert, and Nicole Goutal
- Subjects
Estimation ,Hydrology ,Extended Kalman filter ,Geography ,Data assimilation ,geography.geographical_feature_category ,Meteorology ,Flood forecasting ,Drainage basin ,Context (language use) ,Kalman filter ,Water level - Abstract
The present study describes the assimilation of discharge in situ data for operational flood forecasting. The study was carried out on the Marne River (France) catchment where lateral inflows’ uncertainty is important due to karstic areas. This source of error was partly accounted for using an Extended Kalman Filter (EKF) algorithm built on the top of a mono-dimensional hydraulic model. The lateral inflows were sequentially adjusted over a sliding 48 h time window. The correction leads to a significant improvement in the simulated water level and discharge in re-analysis and forecast modes. These results pave the way for the operational use of the data assimilation (DA) procedure for real-time forecasting at the French flood forecasting service.
- Published
- 2013
25. A Lagrangian finite volume method for the simulation of flows with moving boundaries
- Author
-
Riadh Ata, Azzeddine Soulaïmani, and Francisco Chinesta
- Subjects
Finite volume method ,Collocation ,Flow (mathematics) ,Inviscid flow ,Computation ,Applied mathematics ,Boundary (topology) ,Geometry ,Voronoi diagram ,Boundary knot method ,Mathematics - Abstract
In this paper a Lagrangian formulation of the Natural Element Method (NEM) is proposed to solve shallow water inviscid flows. NEM is a particle‐based method which revealed its capabilities in handling large distortion problems. Its main advantage is the interpolant character of its shape function and consequently the easiness of imposing Dirichlet boundary conditions.In this paper we use the NEM method in a collocation form and in a Lagrangian kinematic description. This formulation is found to be a finite volume methodology with flux computation on the Voronoi diagram of the standard triangular or quadrilateral meshes. The Shallow‐Water equations are used as the mathematical model. Besides the Lagrangian behavior of the flow which is difficult to capture, these equations have discontinuous solutions. Thus, stabilization issues have been considered. Some inviscid bidimensional flows are used as preliminary benchmark tests. This kind of flows is similar to that of metal casting. Good results were found whi...
- Published
- 2007
26. A database of validation cases for tsunami numerical modelling
- Author
-
Damien Violeau, Riadh Ata, Michel Benoit, Antoine Joly, Stéphane Abadie, Lucie Clous, Manuel Martin Medina, Denis Morichon, Jérémie Chicheportiche, Marine Le Gal, Gailler, A., Hélène Hebert, David Imbert, Maria Kazolea, Mario Ricchiuto, Sylvestre Le Roy, Rodrigo Pedreros, Marie Rousseau, Kévin Pons, Richard Marcer, Camille Journeau, Silva Jacinto, R., Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics (LHSV), École des Ponts ParisTech (ENPC)-Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Laboratoire National d’Hydraulique et Environnement (EDF R&D LNHE), EDF R&D (EDF R&D), Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), École Centrale de Marseille (ECM), Université de Pau et des Pays de l'Adour (UPPA), École des Ponts ParisTech (ENPC), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Certified Adaptive discRete moDels for robust simulAtions of CoMplex flOws with Moving fronts (CARDAMOM), Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Principia [La Ciotat], Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ANR-11-RSNR-0023,TANDEM,Tsunamis en Atlantique et MaNche : Définition des Effets par Modélisation(2011), Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics (Saint-Venant), and Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest
- Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,[PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] ,[INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation - Abstract
International audience; This work has been performed by a French national consortium within the framework of the nationalproject Tandem, with aim to improve knowledge about tsunami risk on the French coasts. Workpackage#1 of this project was the opportunity to build a database of benchmark cases to assess the capabilitiesof 18 codes, solving various set of equations with different numerical methods. 14 test cases were definedfrom the existing literature with validation data from reference simulations, theoretical solutions or lab experiments.They cover the main stages of tsunami life: 1) generation, 2) propagation, 3) run-up and submersion,and 4) impact. For each case several of the numerical codes were compared in order to identify the forces andweaknesses of the models, to quantify the errors that these models may induce, to compare the various modellingmethods, and to provide users with recommendations for practical studies. In this paper, 3 representativecases are selected and presented with an analysis of the results.
27. Simulation des écoulements à la surface libre dans des environnements côtiers et estuariens : développement numérique et application sur des maillages non-structurés
- Author
-
Filippini, Andrea Gilberto, Certified Adaptive discRete moDels for robust simulAtions of CoMplex flOws with Moving fronts (CARDAMOM), Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Université de Bordeaux, Mario Ricchiuto, Philippe Bonneton, David Lannes [Président], Michel Benoit [Rapporteur], Eleuterio F. Toro [Rapporteur], Riadh Ata, Rodrigo Pedreros, Lisl Weynans, Ricchiuto, Mario, Bonneton, Philippe, Lannes, David, Benoit, Michel, Toro, Eleuterio F., Ata, Riadh, Pedreros, Rodrigo, Weynans, Lisl, and Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest
- Subjects
Dispersion error ,Finite Volume ,Wave breaking ,Équations de Serre-Green-Naghdi ,Scaling analysis ,Erreur de dispersion ,Mascaret ,Alluvial estuaries ,Serre-Green-Naghdi equations ,Modèle de type Boussinesq ,Estuaires ,Fortement non-linéaire et faiblement dispersif ,Finite element ,Volume Fini ,Boussinesq-type models ,Tidal bore ,Fully nonlinear and weakly dispersive ,Déferlement des vagues ,Élément Fini ,Analyse dimensionnelle ,[MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA] - Abstract
Ces dernières décennies, une attention particulière a été portée sur la modélisation mathématique et la simulation numérique de la propagation de vagues en environnements côtiers. Une description physiquement correcte des phénomènes à grande échelle, qui apparaissent dans les régions d'eau peu profonde, doit prendre en compte de forts effets non-linéaires et dispersifs, ainsi que l'interaction avec des bathymétries complexes. Dans un premier temps, une étude du comportement en régime non linéaire de différents modèles de type Boussinesq est proposée, démontrant l'avantage d'utiliser des modèles fortement non-linéaires par rapport à des modèles faiblement non-linéaires et faiblement dispersifs (couramment utilisés). Ensuite, une nouvelle approche flexible pour résoudre les équations fortement non-linéaires et faiblement dispersives de Green-Naghdi est présentée. Cette stratégie permet d'améliorer un code "shallow water" existant par le simple ajout d'un terme algébrique dans l'équation du moment et est particulièrement adapté à l'utilisation de techniques hybrides pour le déferlement des vagues. De plus, la première discrétisation des équations de Green-Naghdi sur maillage non structuré est proposée via des schémas hybrides Volume Fini/Élément Fini. Finalement, les modèles et méthodes développés dans la thèse sont appliqués à l'étude du problème physique de la formation du mascaret dans des estuaires convergents et alluviaux. Cela a amené à la première caractérisation d'estuaire naturel en terme d'apparition de mascaret.; Over the last decades, there has been considerable attention in the accurate mathematical modeling and numerical simulations of free surface wave propagation in near-shore environments. A physical correct description of the large scale phenomena, which take place in the shallow water region, must account for strong nonlinear and dispersive effects, along with the interaction with complex topographies. First, a study on the behavior in nonlinear regime of different Boussinesq-type models is proposed, showing the advantage of using fully-nonlinear models with respect to weakly-nonlinear and weakly dispersive models (commonly employed). Secondly, a new flexible strategy for solving the fully-nonlinear and weakly-dispersive Green-Naghdi equations is presented, which allows to enhance an existing shallow water code by simply adding an algebraic term to the momentum balance and is particularly adapted for the use of hybrid techniques for wave breaking. Moreover, the first discretization of the Green-Naghdi equations on unstructured meshes is proposed via hybrid finite volume/ finite element schemes. Finally, the models and the methods developed in the thesis are deployed to study the physical problem of bore formation in convergent alluvial estuary, providing the first characterization of natural estuaries in terms of bore inception.
- Published
- 2016
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.