Jean-Michel Hervouet

We present a second order residual distribution scheme for scalar transport problems in shallow water flows. The scheme, suitable for the unsteady cases, is obtained adapting to the shallow water context the explicit Runge-Kutta schemes for scalar equations [1]. The resulting scheme is decoupled from the hydrodynamics yet the continuity equation ha...

In this work, a recent residual distribution scheme and a second-order finite volume method are compared to model the transport of a pollutant in free surface flows. The phenomenon is described in two dimensions using the shallow water (SW) system augmented by a scalar conservation law for the pollutant transport. The two numerical methods are deve...

The flow and sediment transport processes near steep streambanks, which are commonly found in meandering, braided, and anastomosing stream systems, exhibit complex patterns that produce intricate interactions between bed and bank morphologic adjustment. Increasingly, multi-dimensional computer models of riverine morphodynamics are used to aid in th...

Two new species of Benthamia A. Rich. (Orchidaceae) from Madagascar, B. boiteaui Hervouet, sp. nov. and B. bosseri Hervouet, sp. nov., are described. Both have been found at the summit of Ambondrombe (Haute Matsiatra region, near Ambalavao), and also, for B. boiteaui Hervouet, sp. nov. in the Ranomafana national park, and for B. bosseri Hervouet, s...

The present work focuses on the two-dimensional (2D) depth-averaged turbulent flow in shallow rectangular basins. An accurate description of the hydrodynamics is required for further understanding the complex sediment transport processes. This work has practical engineering implication in relation to the rate of sediment deposited in reservoirs. Th...

The application of the European Water Framework Directive and the monitoring obligation on water quality for human consumption and industrial activities create a need for water quality assessment and monitoring systems. The MIGR’Hycar research project (see: http:// www. migrhycar. com), partly funded by the French National Agency for Research (ANR)...

This chapter reviews the numerical anomalies observed when performing numerical simulations of free surface flows, using shallow water equations and a set of transport equations for scalar passive quantities. Some of the anomalies are discrete equations that preserve exactly lake-at-rest steady states, discrete equations that preserve exactly frict...

Identifying efficient solutions to protect coastal regions from marine pollution requires expertise from a range of specialties and strategic approaches. This book gathers information on the impact of oil spills at a coastal level from different experts’ points of view, identifying synergies between domains such as mathematics, numerical modeling,...

The application of the European Water Framework Directive on water quality for human consumption and industrial activities creates a need for water quality assessment and monitoring systems. The MIGR'HYCAR research project was initiated to provide decisional tools for risks connected to oil spills in continental waters. In this paper, the focus is...

The capabilities of the TELEMAC Modelling System to reproduce the formation and evolution of free and forced bars in straight and curved channels are investigated by reproducing the numerical experiments by Defina [5], Bernini et al. [1], Crosato et al. [4] and the laboratory experiences conducted by Whiting and Dietrich [12, 13]. Numerical results...

The application of the European Water Framework Directive and the monitoring obligation on water quality for human consumption and industrial activities create a need for water quality evaluation and monitoring systems. The Migr’Hycar research project was initiated to provide decisional tools, and fulfil operational needs, for risks connected to oi...

This paper highlights the HPC capabilities of TELEMAC-2D, a Finite Element shallow water equation code developed by EDF R&D. A demonstration test case using a 12-million element grid is presented of the flow in the Gironde Estuary in southwest France. Preliminary tests are performed to study round-off error propagation which might be amplified when...

In the centre of the Gironde estuary, EDF exploits a power plant. A hydrodynamic model is required to prevent different risks. Indeed, accurate water levels and velocity field are needed for flood control, sediment transport and associated deposition and transport of algae or pollutant. In order to enhance the accuracy of the hydrodynamic results a...

Notations and concepts in geometryFree surface Navier–Stokes equationsSaint-Venant equationsModelling of turbulence and dispersion

IntroductionEquations with hydrostatic hypothesisNon-hydrostatic Navier?Stokes equationsPseudo wave equation, a variant of the hydrostatic stepTracer equation in 3DThe conservation of mass in 3DSources and sinks in the Navier?Stokes equationsTreatment of uncovered beds in 3D

Malpasset dam-break waveTides in the English Channel and the Atlantic OceanSolitary waveFlow of two fluids of different densities

IntroductionPrinciple of the adjoint methodTreatment of Dirichlet conditionsApplication to Telemac-2D algorithmDescent methods for minimizing the cost functionValidation and results

IntroductionInterpolation in finite elementsVariational principle

Method of characteristicsStreamline Upwind Petrov–Galerkin methodConservative scheme for the continuity equationDistributive schemes

Plates 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

Latin alphabetGreek alphabetMathematical signs

IntroductionPartition of the domainRequested dataCommunication between processorsAdaptation of the algorithmsResults

A glance at the existing methodsOverall view of the Telemac-2D algorithmFractional steps methodAdvection stage using the method of characteristicsPropagation, diffusion, source termsRadiation conditionsResolution of the Boussinesq equationsResolution of k–ε model equations in 2DSolving the tracer equation in 2DLaws of conservation in 2DThe treatmen...

This paper formulates a finite volume analogue of a finite element schematization of three-dimensional shallow water equations. The resulting finite volume schematization, when applied to the continuity equation, exactly reproduces the set of matrix equations that is obtained by the application of the corresponding finite element schematization to...

Two common strategies for solving the shallow water equations in the finite element community are the generalized wave continuity equation (GWCE) reformulation and the quasi-bubble velocity approximation. The GWCE approach has been widely analysed in the literature. In this work, the quasi-bubble equations are analysed and comparisons are made betw...

Résumé: Cet article illustre par des exemples l'intérêt des approches intégrée et couplée pour le calcul des évolutions sédimentaires. On y aborde, dans le cadre du système hydro-informatique Telemac, le couplage entre hydrodynamique et charriage sur le fond, le traitement simultané du charriage et de la suspension, et le calcul intégré de l'hydrod...

On propose dans cet article une nouvelle méthode pour le traitement des fonds rigides dans les codes de calcul d'évolution morphodynamique. Les évolutions du fond sont dues à la divergence du transport solide, et la méthode proposée consiste à assurer, par une limitation de ce transport solide, une valeur de sa divergence qui interdise une érosion...

On propose dans cet article une méthode pour résoudre les équations de Navier- Stokes à surface libre, sans hypothèse de pression hydrostatique, dans le cadre de la méthode des éléments finis. L'algorithme inclut une étape où l'hypothèse de pression hydrostatique est conservée. Les résultats montrent la robustesse de l'approche et prouvent que les...

This paper deals with the numerical solution of 3-dimensional Navier-Stokes equations with a free surface, in the framework of finite elements. The hydrostatic assumption is not done but the algorithm is built as an extension of an already existing hydrostatic Navier-Stokes solver. The results prove the robustness of the approach and show that the...

In this paper a new method for dealing with rigid beds in saturated bed load transport equation is proposed. The divergence of the bed load transport is responsible for the variations of bed elevation, and the method consists of finding a limitation of this bed load transport which ensures a limitation of its divergence so that the rigid bed is not...

This paper attempts to assess the accuracy of constant eddy viscosity, Elder and k–ϵ turbulence models in the numerical simulation of reach-scale compound channel flows using two-dimensional (2D) finite element methods. Assessment was conducted using benchmark stage-discharge data collected from straight and meandering compound channel configuratio...

A numerical study of optimal estimation of bottom friction parameters associ- ated with fluvial flow for a two-dimensional finite element code is reported. Although floodplain-channel friction coefficients are an a priori requirement for the solution of the St. Venant Equations, their values are not directly mea- surable. The friction coefficients...

The evolution of laws on dam safety in France is briefly described. Most simulation studies for such problems are currently attempted using one-dimensional models, and we investigate here the possibility of moving to two-dimensional simulations. To date, these have been constrained by lack of available computational power. Parallel processing is an...

The past 20 years have seen a proliferation of numerical models in response to a need from governments, industry and researchers for tools that can simulate or predict environmental processes. Although this has led to significant scientific advances, in constructing such models code developers duplicate many basic tasks and functions. Ultimately th...

This paper discusses the development of a two-dimensional finite element coupled hydraulic-sediment transport scheme for application to lowland floodplain environments. Recent developments in numerical algorithms have led to the development of two- and three-dimensional hydraulic models which are capable of simulating open channel and floodplain hy...

The numerical solutions of three-dimensional, non-hydrostatic Navier-Stokes equations are compared to the ones obtained with Boussinesq equations in the case of a solitary wave in a rectangular channel. The solution procedures used in Telemac-2D for Boussinesq and in Telemac-3D for Navier-Stokes are presented and the numerical results are compared,...

Malpasset dam-break occurred in the south of France in 1959 and caused 421 casualties. This unique example of total failure of an arch dam makes it a case of utmost interest for testing and validating software. In the past, a scale model and a one-dimensional computation have been used to reproduce the accident. This paper presents two-dimensional...

Dynamic moving–boundary problems are a common occurrence in shallow–water hydraulics, yet no generally applicable or computationall efficient framework is available for their solution. In this paper a new scheme is presented that attempts to solve the proble of representing moving–boundary shallow–water hydrodynamics on fixed numerical grids. The s...

Through the steady improvements in hardware and algorithms, an ever increasing use of digital modelling can be made in fluid mechanics. Meanwhile, the rising environment-related problems and the concurrent water uses raise more and more complex and multidisciplinary issues. Consequently, the fields of application for numerical simulation are becomi...

Recent work has illustrated the potential of two dimensional finite element codes for modelling flow in meandering compound channels [1,2,3,4,5]. Such models have been shown to offer a number of advantages over alternative one [6,7] and two [8] dimensional finite difference schemes due to their ability to represent complex topography with a minimum...

Cet article s'intéresse à la simulation numérique d'écoulements à surface libre à l'échelle de la rivière. Une prédiction précise de tels écoulements serait une avancée majeure à la fois pour l'ingénierie hydraulique et l'occupation des sols. Jusqu'à maintenant, cet objectif a été difficile à atteindre en raison de la complexité du modèle et du man...

Two-dimensional, finite element hydraulic models have been developed to simulate river flood flows at high spatial and temporal resolutions over river reach lengths of 1–60 km. Such models have been shown to be capable of simulating bulk flow; however, model redesign to predict spatially distributed hydraulic variables has been constrained by lack...

While initial studies have demonstrated the feasibility of applying two-dimensional finite element models to reach scale river flood flows, the further development and practical use of such codes for engineering problems has been hampered by a lack of available validation data. This paper attempts to address this research need by conducting benchma...

This paper describes results from a recent study concerning the numerical modelling of compound channel flow using two generalized two-dimensional finite element codes specifically adapted to floodplain studies: RMA-2 and TELEMAC-2D. By application to an 11 km reach of the River Culum, Devon, UK, simulations are developed to investigate the impact...

Recent numerical modelling developments have made the application of two-dimensional finite element codes to the simulation of river flood inundation over reach lengths of 10-30 km a viable proposition. Currently, however, one-dimensional finite difference codes are the standard analytical tool for many engineering applications. This paper presents...

Presentation of the different computer programmes in the TELEMAC system, dedicated to free-surface flows. This system includes user interfaces and all pre and post-processors, along with fluid mechanics programmes using the same Finite Element library. After a period of internal use at Electricite de France, this system is now available for other u...

This paper reports on an attempt to begin a rigorous field testing programme for two dimensional finite element flow models, examining the impacts of mesh resolution and numerical method on simulation results. To achieve this a two dimensional finite element model, TELEMAC-2D, has been applied to an 11 km reach of the River Culm, Devon, UK for whic...

Describes the algorithm of MITHRIDATE, a code currently under development for three dimensional free surface flow problems. The code will be useful for problems involving pollution, thermal dilution, or suspended sediment transport. Using finite element techniques, the computation takes full advantage of vectorization. Results for two test cases, f...

Quelques codes recents sont decrits: NSL pour la houle, LIDO, TELEMAC et MITRIDATE pour les ecoulements a surface libre peu cambree. On considere l'evolution des methodes de travail et l'environnement des logiciels de calcul

The experience acquired by LNH for about thirty years allows to set up powerful numerical methods, relying on new techniques developed by mathematicians and using the progress of computers. Numerical models could also benefit from an advanced knowledge in the physical processes. Some of these tools are presented here: NSL for wave propagation simul...

During the past ten years various methods have been devised to deal with the solution of the Navier–Stokes equations. In the meantime, different models have been worked out to represent turbulent incompressible flows. At LNH, deep participation in this enthusiastic research is still going on, together with a closely related development of physical...

This chapter discusses computation of currents due to wind and tide in a lagoon with depth-averaged Navier-stokes equations (Ulysse code). The original feature of the computation lies in the unknowns of the momentum equations: Usually in the shallow water equations the unknowns are the velocity and the water depth (or the free-surface elevation). H...

The author presents the application of the method of characteristics in their weak formulation to mesh grids. The different techniques allowing the theory to be developed numerically are given in detail, with, in particular, a new exact method of quadrature derived from the theory of distributions. The tests presented, in particular that of the rot...

Codes developped at LNH for solution of Navier-Stokes equations share as a common feature the use of fractional step schemes: Each time step is decomposed into substeps, corresponding to physical phe- nomena (convection, diffusion, continuity — i.e., mass conservation), of different kinds (hyperbolic, parabolic, elliptic). In our implementation we...

Coastal erosion and flooding are largely determined by extreme wave action and nearshore wave heights are controlled through energy dissipation on offshore sandbanks. East Anglia is the area of study here. The finite-element codes for tidal flows (TELEMAC-2D), for wave propagation (TOMAWAC) and for morphodynamics (SISYPHE), are used for this study....