Publications

2015

• Finite volume schemes and residual distribution schemes for pollutant transport on unstructured grids
  
  • Pavan Sara
  • Ata Riadh
  • Hervouet Jean-Michel
  Environmental Earth Sciences, Springer, 2015, 74 (11). 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 developed to minimize the numerical diffusion which is a critical problem for transport phenomena. The conservation of the mass and the monotonicity of the solution are two other important numerical requirements necessary to reproduce the physics of the problem. These three features (low numerical diffusion—mass conservation—monotonicity) will be theoretically analyzed and then numerically verified through a series of test cases. Both methods are used on completely unstructured grids, but the regularity of the grid with respect to the streamlines direction produces for the two methods different behaviours which will be studied. This work has been realized within the Telemac-2D system, constituted by a finite element kernel and a finite volume kernel. Telemac2D uses several numerical schemes, including the new schemes presented here. The aim of this paper is to present state-of-the-art research in the field of finite volumes (FV) and of residual distribution schemes for advection problems. © 2015, Springer-Verlag Berlin Heidelberg. (10.1007/s12665-015-4760-5)
  DOI : 10.1007/s12665-015-4760-5
• Using the DRAGFO subroutine to model Tidal Energy Converters in Telemac-2D
  
  • Joly Antoine
  • Pham Chi-Tuân
  • Andreewsky Marc
  • Saviot Sylvain
  • Fillot Lauriane
  , 2015. In the past few years the research on Tidal Energy Converters (TECs), or Tidal Turbines, has increased (see for example the work done at the EMEC 1). As such a demand arose to assess the impact of potential large industrial TEC farms. This demand has also been growing in the Telemac User community, see for example Haverson et al. [2] or de Paula Kirinus et al. [1], but no clear methodology has been defined within the Telemac-Mascaret system. To model the hydrodynamic effects of TEC over large areas, two approaches are possible. One can either use the actuator disk method, where the influence of a TEC is modelled through a head drop [6], or it is possible to model the drag force induced by a TEC opposing the flow (this can be thought of as being similar to increasing the bed friction). This second approach has been successfully applied by EDF in Telemac-2D through the PerAWaT project 2 and its recommended implementation in Telemac-2D will be described in this article. Furthermore its implementation will be illustrated by reproducing the experiment conducted by the University of Manchester within the PerAWaT project [7].
• Adding boundary conditions on the bed for Telemac-3D simulations
  
  • Joly Antoine
  • Leroy Agnès
  , 2015. Telemac-3D has been developed to work on a two dimensional mesh that has been extruded along the z-axis. Ongoing work is done by the development team to move away from this structure. The work presented here, and available in version 7.1 of Telemac-3D, is the first step of this process as it will extend the available external boundary conditions to the bed. The impact of imposing a flow rate on the bed on the equations solved by Telemac-3D and on the hypotheses chosen will be developed. The use of these new boundary conditions in a Telemac-3D simulation will then be explained. These boundary conditions will then be illustrated through a simple test case through a comparison with source terms, which was the only available method in the previous versions of Telemac-3D to model inflow near the bed.
• The hydrodynamic, sea-state and infrastructures platform developed by Saint-Venant Hydraulics Laboratory and Cerema: a special focus on the TELEMAC2D surge levels numerical model of the Atlantic Ocean, the Channel and the North Sea
  
  • Laborie Vanessya
  • Sergent Philippe
  • Levy Florence
  • Frau Roberto
  • Weiss Jérôme
  , 2015.
• Estimation des niveaux marins extrêmes avec et sans l’action des vagues le long du littoral métropolitain
  
  • Kergadallan Xavier
  , 2015. Pour caractériser le risque de submersion marine, il est très important d'avoir une connaissance précise des lois de distribution des niveaux d'eau marins, et plus particulièrement des niveaux d'eau extrêmes. En effet ce sont eux qui sont à l'origine des conséquences les plus dramatiques. Le programme de recherche mené au cours de cette thèse a été financé par le Ministère de l'Écologie, du Développement Durable et de l'Énergie. L'objectif final est de fournir des valeurs de référence de niveau d'eau marin le long des côtes françaises, par le biais d'une méthode d'analyse statistique des extrêmes. Ces niveaux comprennent les trois composantes suivantes : la marée, la surcote météorologique et le wave set-up. Le principe de base utilisé est le suivant : une analyse statistique est effectuée aux ports où la donnée marégraphique est disponible, puis le résultat est interpolé entre les ports. Différentes approches sont testées. Les points suivants sont en particulier étudiés :- la dépendance marée surcote, avec deux différents types de dépendance, une dépendance temporelle et une dépendance en amplitude ;- la méthode d'interpolation, avec la comparaison d'une analyse site-par-site (ASS) avec une analyse régionale (RFA), et celle d'interpolations 1D et 2D ;- l'estimation du wave set-up, basée sur l'état de l'art des formules paramétriques ;- la dépendance surcote vagues, avec des lois bi-variées de valeurs extrêmes. Le résultat final se présente sous la forme de deux profils de niveau d'eau de période de retour 100 ans : le premier sans l'action des vagues (marée et surcote météorologique) et le deuxième avec l'action des vagues. Les valeurs les plus élevées sont atteintes, pour le littoral de la Mer du Nord, la Manche et l'Atlantique, en Baie du Mont-Saint-Michel (à cause des conditions de marée), et pour le littoral méditerranéen au niveau de Marseille. L'analyse montre que la modélisation de la dépendance temporelle marée surcote n'influe pas significativement sur les estimations des valeurs extrêmes. Par contre la modélisation de la dépendance en amplitude donne des résultats intéressants pour certains ports. En comparaison avec l'ASS, la RFA tend à lisser les résultats. Les estimations issues de la RFA sont supérieures pour le littoral méditerranéen, et équivalentes pour le littoral de Mer du Nord, Manche et Atlantique. La RFA serait recommandée pour l'estimation des niveaux de retour en dehors du domaine de validité de l'ASS.À cause du petit nombre de sites d'observation, il est préféré une interpolation 1D le long du trait de côte lissé. Le wave set-up est calculé par la formule de Dean et Walton [2009].La dépendance surcote vagues est moyenne le long du littoral méditerranéen. Le facteur de dépendance montre des variations plus importantes le long du littoral de Mer du Nord, Manche et Atlantique, avec un maximum observé en Baie de Seine et des minima en Baie de Mont-Saint-Michel et au niveau de Calais. Des suggestions sont faites pour améliorer les méthodologies développées et appliquées dans le cadre d'un futur travail (10.70675/6a2d2cb1z935cz42cfz84dez41e22d827821)
  DOI : 10.70675/6a2d2cb1z935cz42cfz84dez41e22d827821
• Modélisation de fermes de systèmes houlomoteurs : effets d’interactions entre systèmes à l’échelle de la ferme et impact sur le climat de vagues à l'échelle régionale
  
  • Charrayre François
  , 2015. Cette thèse porte sur le développement d'un ensemble d'outils numériques destinés à simuler différents aspects des interactions vagues-structure appliquées à l'exploitation des systèmes de récupération de l'énergie des vagues (SREV). Elle a été réalisée dans le cadre du projet ANR Monacorev (projet ANR11-MONU-018-01, 2012-2015).L'objectif est de pouvoir traiter la question des interactions à l'échelle d'une ferme de SREVs (≈ 1 km), et d'étudier l'impact d'une ou plusieurs fermes de SREVs à l'échelle régionale (≈ 10km) sur le champ de vague total. Des méthodes de modélisation et de simulation adaptées sont développées pour chacune de ces deux échelles. Jusqu'à présent, les interactions entre les SREVs étaient bien souvent étudiées en considérant que le fond était plat (l'influence d'un fond variable sur le champ de houle au niveau de la ferme étant alors jugé négligeable), ce qui permet de calculer facilement et rapidement le champ de vagues et les interactions grâce à l'utilisation de la théorie linéaire potentielle. Une application pratique de cette méthode est le calcul du rendement d'une ferme de SREVs, et l'optimisation de leurs positions relatives au sein d'un parc. Dans le cadre de la théorie linéaire, cette thèse propose une méthodologie de couplage originale entre un code de tenue à la mer (Aquaplus) et un code de propagation de la houle en zone côtière (Artemis), laquelle a été développée et qualifiée. Les simulations réalisées montrent que, pour une configuration de ferme de SREVs donnée, on ne peut pas toujours négliger les effets de la bathymétrie. Par exemple, la présence d'une plage de pente 10% au large d'une ferme de SREV peut modifier la hauteur des vagues de manière significative, et affecter ainsi le rendement de la ferme de manière significative par rapport au cas où le fond est uniformément plat. A l'échelle côtière régionale, il est aussi intéressant de simuler et prédire l'impact de fermes de SREVs sur le champ de vagues. Pour des raisons d'efficacité, une approche à phases moyennées de modélisation des vagues a été privilégiée, fondée sur le code spectral d'états de mer Tomawac. La représentation des effets d'un SREV à travers l'utilisation d'un terme puits (concept permettant de soustraire au spectre d'énergie d'état de mer local l'énergie correspondant à celle absorbée par le SREV), bien qu'incomplète du fait que les effets de radiation/diffraction ne sont pas pris en compte, a été étudiée et testée. Une nouvelle méthodologie prenant en compte ces effets dans un code spectral est présentée ici et testée, avec l'objectif de pallier à ces limitations. Les discussions sur la validité de deux approches permettent d'esquisser des pistes de développements ultérieurs pour la représentation des fermes de SREV à l'échelle régionale (10.70675/d9d0ba42zcd55z486dzbba8zfbdf2e1d06d5)
  DOI : 10.70675/d9d0ba42zcd55z486dzbba8zfbdf2e1d06d5
• Introducing Second Order Low Frequency Loads in the Open-Source Boundary Element Method Code Nemoh
  
  • Philippe Maxime
  • Combourieu Adrien
  • Peyrard Christophe
  • Robaux Fabien
  • Delhommeau Gérard
  • Babarit Aurélien
  , 2015. This paper describes the implementation of the second order low frequency loads in the opensource potential flow solverNemoh. Thequadratic part of the difference frequency quadratic transfer functions (QTF-),depending on first order quantities, is implemented using the near-field approach.Results are compared with reference results from the literature. A good agreement is found for a fixed and a mobile hemisphere, and for a vertical cylinder of two different depths. The potential part is calculated using the Pinkster approximation. Those developments allow computing the low frequency QTF (quadratic transfer function), within the opensource boundary element method solver Nemoh.
• Nonlinear modelling of wave-structureinteractions applied to off shorewind turbine platforms
  
  • Dombre Emmanuel
  , 2015. This PhD work is devoted to the study of nonlinear interactions between waves and floating rigid structures. The developed model relies on a boundary element method which reduces the dimensionality of the problem by one. First, a 2D model is applied to basic geometries and allows us to demonstrate the validity of the method for predicting the motion of a floating structrure subject to incoming monochromatic regular waves. Secondly, getting inspired by the 3D fully nonlinear potential flow model of Grilli textit{et al.}~cite{grilli2001fully}, we propose a novel model which generalizes the method for unstructured triangular meshes of 3D surfaces. The proposed model is able to deal with arbitrary configurations of multiple vertical cylinders interacting with the waves. We present academic validation test cases which show how the model works and behaves. Finally, we study situations of interest for EDF R&D related to floating off-shore wind turbines. A semi-submersible platform is evaluated with the nonlinear model (10.70675/152921edzaac6z41a3z8cddz4d70155d6dc4)
  DOI : 10.70675/152921edzaac6z41a3z8cddz4d70155d6dc4
• Evolution of surge levels inside of the Seine Bay : interactions between tide and surge levels during Johanna and Xynthia storms
  
  • Laborie Vanessya
  • Cerema Philippe Sergent
  , 2015, 17, pp.2015 - 11299. Within the Technical Commission for the Study and the Evaluation of Maritime Submersions in the Seine Estuary (CTeeSMES), which aim is to improve the collective knowledge on physical processes related to maritime surge levels, a numerical model of the Atlantic French Coast based on TELEMAC2D was used to study the evolution of surge levels from the ocean to the harbour area of Le Havre and evaluate the interactions between tide and surge levels in the Seine Bay. The numerical model was specifically calibrated on JOHANNA and XYNTHIA storm events, which respectively occurred in March 2008 and in February 2010. To calibrate the global signal (tide + surge levels), measurements available on 18 outputs of the Atlantic coast were used to optimize the coefficient for wind influence and for bottom friction. Maritime boundary conditions were provided by the North East Atlantic Atlas (LEGOS). Winds and pressure fields were CFSR data. Once the numerical model had been calibrated both for tide and surge levels, it has been possible to draw the evolution of surge levels from the ocean to Le Havre (quai Meunier) and then to compare the signal obtained at each point of the Seine Bay with that obtained without taking into consideration tide for each event. That also allowed to evaluate the contribution of interactions between tide and surge levels inside of the Seine Bay for Xynthia and Johanna events, but also for other events in the slice [1979-2010] and considering climate change towards 2100 with IPCC5 scenarios. It appears that instantaneous interactions between tide and surge levels nearly reach 50 % of the global surge levels and can sharply influence the evolution of surge levels in the Seine Bay depending of the moment (high tide or low water) at which the storm occurs.
• NUMERICAL SIMULATIONS OF THE PERIODIC INVISCID BURGERS EQUATION WITH STOCHASTIC FORCING
  
  • Audusse Emmanuel
  • Boyaval Sébastien
  • Gao Yueyuan
  • Hilhorst Danielle
  , 2015, 48, pp.308-320. We perform numerical simulations in the one-dimensional torus for the first order Burgers equation forced by a stochastic source term with zero spatial integral. We suppose that this source term is a white noise in time, and consider various egularities in space. For the numerical tests, we apply a finite volume scheme combining the Godunov numerical flux with the Euler-Maruyama integrator in time. Our Monte-Carlo simulations are analyzed in bounded time intervals as well as in the large time limit, for various regularities in space. The empirical mean always converges to the space-average of the (deterministic) initial condition as t → ∞, just as the solution of the deterministic problem without source term, even if the stochastic source term is very rough. The empirical variance also stablizes for large time, towards a limit which depends on the space regularity and on the intensity of the noise.
• Hybridization of Mixed High-Order Methods on General Meshes and Application to the Stokes Equations
  
  • Aghili Joubine
  • Boyaval Sébastien
  • Di Pietro Daniele
  Computational Methods in Applied Mathematics, De Gruyter, 2015. This paper presents two novel contributions on the recently introduced Mixed High-Order (MHO) methods [`Arbitrary order mixed methods for heterogeneous anisotropic diffusion on general meshes', preprint (2013)]. We first address the hybridization of the MHO method for a scalar diffusion problem and obtain the corresponding primal formulation. Based on the hybridized MHO method, we then design a novel, arbitrary order method for the Stokes problem on general meshes. A full convergence analysis is carried out showing that, when independent polynomials of degree k are used as unknowns (at elements for the pressure and at faces for each velocity component), the energy-norm of the velocity and the L2-norm of the pressure converge with order (k + 1), while the L2-norm of the velocity (super-)converges with order (k + 2). The latter property is not shared by other methods based on a similar choice of unknowns. The theoretical results are numerically validated in two space dimensions on both standard and polygonal meshes. (10.1515/cmam-2015-0004)
  DOI : 10.1515/cmam-2015-0004
• Optimal time step for incompressible SPH
  
  • Violeau Damien
  • Leroy Agnès
  Journal of Computational Physics, Elsevier, 2015, 288, pp.119-130. (10.1016/j.jcp.2015.02.015)
  DOI : 10.1016/j.jcp.2015.02.015
• Considering hazard estimation uncertain in urban resilience strategies
  
  • Barroca Bruno
  • Bernadara Pietro
  • Girard Stéphane
  • Mazo Gildas
  Natural Hazards and Earth System Sciences, Copernicus Publ. / European Geosciences Union, 2015, 15 (1), pp.25-34. Urbanization has led to a higher concentration of both persons and property, which increases the potential degree of damage liable to occur in crisis situations. Urban areas have become increasingly complex socio-technical systems where the inextricable tangle of activities, networks and regions means disruptions propagate rather than disseminate. In risk anticipation, measures of prevention and anticipation are generally defined by using hazard modelling. The relevance of this approach may be subject to discussion (Zevenbergen et al., 2011) particularly in view of the large number of uncertainties that make hazard evaluation so difficult. For this reason, uncertainty analysis is initially called upon in a theoretical approach before any applied approach. Generally, the uncertainty under study is not assessed in hydrological studies. This uncertainty is related to the choice of evaluation model used for extreme values. This application has been used on the territory of the town of Besançon in eastern France. Strategic orientations for regional resilience are presented taking into account the high levels of uncertainty concerning estimates for possible flow rates. (10.5194/nhess-15-25-2015)
  DOI : 10.5194/nhess-15-25-2015
• Buoyancy modelling with incompressible SPH for laminar and turbulent flows
  
  • Leroy Agnès
  • Violeau Damien
  • Ferrand Martin
  • Joly Antoine
  International Journal for Numerical Methods in Fluids, Wiley, 2015, 78 (8), pp.455 - 474. This work aims at modelling buoyant, laminar or turbulent flows, using a 2D Incompressible Smoothed Particle Hydrodynamics (ISPH) model with accurate wall boundary conditions. The buoyancy effects are modelled through the Boussinesq approximation coupled to a heat equation, which makes it possible to apply an incompressible algorithm to compute the pressure field from a Poisson equation. Based on our previous work (Leroy et al., 2014), we extend the unified semi-analytical wall boundary conditions to the present model. The latter is also combined to a Reynolds-Averaged Navier-Stokes approach to treat turbulent flows. The k − turbulence model is used, where buoyancy is modelled through an additional term in the k − equations like in mesh-based methods. We propose a unified framework to prescribe isothermal (Dirichlet) or imposed heat flux (Neumann) wall boundary conditions in ISPH. To illustrate this, a theoretical case is presented (laminar heated Poiseuille flow), where excellent agreement with the theoretical solution is obtained. Several benchmark cases are then proposed: a lock-exchange flow, two laminar and one turbulent flow in differentially heated cavities, and finally a turbulent heated Poiseuille flow. Comparisons are provided with a Finite-Volume (FV) approach using an open-source industrial code. (10.1002/fld.4025)
  DOI : 10.1002/fld.4025
• Unified semi-analytical wall boundary conditions in SPH: analytical extension to 3-D
  
  • Mayrhofer Arno
  • Ferrand Martin
  • Kassiotis Christophe
  • Violeau Damien
  • Morel François-Xavier
  Numerical Algorithms, Springer Verlag, 2015, 68 (1). (10.1007/s11075-014-9835-y)
  DOI : 10.1007/s11075-014-9835-y
• Sea-state modification and heaving float interaction factors from physical modelling of arrays of wave energy converters
  
  • Stratigaki Vicky
  • Troch Peter
  • Stallard Tim
  • Forehand David
  • Folley Matt
  • Kofoed Jens-Peter
  • Benoit Michel
  • Babarit Aurélien
  • Vantorre Marc
  • Kirkegaard J.
  Journal of Renewable and Sustainable Energy, AIP Publishing, 2015, 7 (6), pp.061705. Wave energy converters (WECs) extract energy from ocean waves and have the potential to produce a significant amount of electricity from a renewable resource. However, large “WEC farms” or “WEC arrays” (composed of a large number of individual WECs) are expected to exhibit “WEC array effects”. These effects represent the impact of the WECs on the wave climate at an installation site, as well as on the overall power absorption of the WEC array. Tests have been performed in the Shallow Water Wave Basin of DHI (Denmark) to study such “WEC array effects”. Large arrays of up to 25 heaving point absorber type WECs have been tested for a range of geometric layout configurations and wave conditions. Each WEC consists of a buoy with a diameter of 0.315 m. Power take-off was modeled by realizing friction based energy dissipation through damping of the WECs' motion. The produced database is presented: WEC response, wave induced forces on the WECs, and wave field modifications have been measured. A first understanding of WEC array effects is obtained. This unique experimental set-up of up to 25 individual WEC units in an array layout, placed in a large wave tank, is at present the largest set-up of its kind studying the important WEC array effects. The data obtained from these experimental tests will be very useful for validation and extension of numerical models. This model validation will enable optimization of the geometrical layout of WEC arrays for realistic wave farm applications and reduction of the cost of energy from wave energy systems. (10.1063/1.4938030)
  DOI : 10.1063/1.4938030
• Field evidence of beach profile evolution toward equilibrium: EQUILIBRIUM BEACH PROFILE EVOLUTION
  
  • Ludka B. C.
  • Guza R. T.
  • O'Reilly W. C.
  • Yates M. L.
  Journal of Geophysical Research. Oceans, Wiley-Blackwell, 2015, 120 (11), pp.7574-7597. (10.1002/2015jc010893)
  DOI : 10.1002/2015jc010893
• Algorithmic differentiation applied to the optimal calibration of a shallow water model
  
  • Demangeon Félix
  • Goeury Cédric
  • Zaoui Fabrice
  • Goutal Nicole
  • Pascual Valérie
  • Hascoët Laurent
  La Houille Blanche - Revue internationale de l'eau, EDP Sciences, 2015. The information on sensitivity provided by derivatives is indispensable in many fields of science. In numerical analysis, computing the accurate value of the derivatives of a function can be a challenge. The classical Finite Differences (FD) method is a simple solution to implement when estimating the value of a derivative. However, it remains highly sensitive numerically and costly in calculation time. Conversely, the Algorithmic Differentiation Method (AD) is a powerful tool for calculating the derivatives of a function described by a computer program. Whatever the complexity of the algorithms implemented in the expression of a function, AD calculates its derivative accurately and reduces development efforts. This article presents the contribution of AD in comparison to FD in the problem of calibrating an industrial class 1D shallow water model. Model calibration is performed by a deterministic mathematical optimiser requiring accurate calculation of the sensitivity of the water surface profile in relation to the friction on a river bed. Two comparative real test cases are presented. They permit validating the better performance expected from AD as a tool used to obtain optimal calibration.
• Modeling of SMF tsunami hazard along the upper US East Coast: detailed impact around Ocean City, MD
  
  • Grilli Stephan T.
  • O’reilly Christopher
  • Harris Jeffrey C.
  • Bakhsh Tayebeh Tajalli
  • Tehranirad Babak
  • Banihashemi Saeideh
  • Kirby James T.
  • Baxter Christopher D. P.
  • Eggeling Tamara
  • Ma Gangfeng
  • Shi Fengyan
  Natural Hazards, Springer Verlag, 2015, 76 (2), pp.705-746. (10.1007/s11069-014-1522-8)
  DOI : 10.1007/s11069-014-1522-8
• Far-Field Tsunami Impact in the North Atlantic Basin from Large Scale Flank Collapses of the Cumbre Vieja Volcano, La Palma
  
  • Tehranirad Babak
  • Harris Jeffrey C.
  • Grilli Annette R.
  • Grilli Stephan T.
  • Abadie Stéphane
  • Kirby James T.
  • Shi Fengyan
  Pure and Applied Geophysics, Springer Verlag, 2015, 172 (12), pp.3589-3616. (10.1007/s00024-015-1135-5)
  DOI : 10.1007/s00024-015-1135-5
• Numerical Simulation of the Dynamics of Sedimentary River Beds with a Stochastic Exner Equation
  
  • Audusse Emmanuel
  • Boyaval Sébastien
  • Goutal Nicole
  • Jodeau Magali
  • Ung Philippe
  ESAIM: Proceedings and Surveys, EDP Sciences, 2015, 48, pp.321 - 340. At the scale of a river reach, the dynamics of the river bed is typically modelled by Exner equation (conservation of the solid mass) with an empirical solid flux of transported sediments, which is a simple deterministic algebraic formula function of i) the sediment physical characteristics (size and mass) and of ii) the averaged hydrodynamical description of the ambient water flow. This model has proved useful, in particular through numerical simulations, for hydraulic engineering purposes (like estimating the mass of sediments that is drained through an open dam). Though, the model is also coarse. And its applicability at various space and time scales remains a question of considerable interest for sedimentologists. In particular, physical experiments from the grain scale to the laboratory scale reveal important fluctuations of the solid flux in given hydrodynamical conditions. This work is a preliminary study of the coupling of a stochastic Exner equation with a hydrody-namical model for large scales. (Stochastic models with a probabilistic solid flux are currently being investigated, but most often only from the viewpoint of theoretical physics at the grain scale.) We introduce a new stochastic Exner model and discuss it using numerical simulations in an appropriate test case. (10.1051/proc/201448015)
  DOI : 10.1051/proc/201448015
• Accuracy and efficiency of two numerical methods of solving the potential flow problem for highly nonlinear and dispersive water waves
  
  • Yates Marissa L.
  • Benoit Michel
  International Journal for Numerical Methods in Fluids, Wiley, 2015, 77, pp.616-640. SUMMARY The accuracy and efficiency of two methods of resolving the exact potential flow problem for nonlinear waves are compared using three different 1DH test cases. The two model approaches use high-order finite difference schemes in the horizontal dimension and differ in the resolution of the vertical dimension. The first model uses high-order finite difference schemes also in the vertical, while the second model applies a spectral approach. The convergence, accuracy, and efficiency of the two models are demonstrated as a function of the temporal, horizontal, and vertical resolution for (1) the propagation of regular nonlinear waves in a periodic domain, (2) the motion of nonlinear standing waves in a domain with fully reflective boundaries, and (3) the propagation and shoaling of a train of waves on a slope. The spectral model approach converges more rapidly as a function of the vertical resolution. In addition, with equivalent vertical resolution, the spectral model approach shows enhanced accuracy and efficiency in the parameter range used for practical model applications. (10.1002/fld.3992)
  DOI : 10.1002/fld.3992
• Alternate bars in a sandy gravel bed river: generation, migration and interactions with superimposed dunes: ALTERNATE BARS: GENERATION, MIGRATION AND INTERACTIONS
  
  • Rodrigues Stéphane
  • Mosselman Erik
  • Claude Nicolas
  • Wintenberger Coraline
  • Jugé Philippe
  Earth Surface Processes and Landforms, Wiley, 2015, 40 (5), pp.610-628. (10.1002/esp.3657)
  DOI : 10.1002/esp.3657
• A conceptual morphodynamic model including storm impacts for microtidal barred beaches
  
  • Gervais Mathieu
  • Balouin Yann
  • Certain Raphael
  , 2015, pp.6 pages. This paper introduces the main results of a large dataset concerning the impacts of storm events and recovery period on a microtidal double barred beach of the NW Mediterranean Sea (Lido de Sète, Gulf of Lions, South France). The objective is to discuss of the key control parameters among both the forcing conditions and the morphological state of the bar/beach system. Our new dataset (high frequency topo-bathymetries and ARGUS video) clearly demonstrates the importance of the morphological variations in bar pattern along the beach. The steady alongshore difference in the outer bar depth and distance (maintained by the N.O.M. variations) has a concrete influence on the modal inner bar state and sensitivity of bar and beach profile face to the erosive processes. (10.5150/cmcm.2015.057)
  DOI : 10.5150/cmcm.2015.057
• One-dimensional numerical modelling of solute transport in streams: The role of longitudinal dispersion coefficient
  
  • El Kadi Abderrezzak Kamal
  • Ata Riadh
  • Zaoui Fabrice
  Journal of Hydrology, Elsevier, 2015, 527, pp.978-989. (10.1016/j.jhydrol.2015.05.061)
  DOI : 10.1016/j.jhydrol.2015.05.061