Publications

2014

• Interactions between flow structure and morphodynamic of bars in a channel expansion/contraction, Loire River, France
  
  • Claude Nicolas
  • Rodrigues Stéphane
  • Bustillo Vincent
  • Bréhéret Jean-Gabriel
  • Tassi Pablo
  • Jugé Philippe
  Water Resources Research, American Geophysical Union, 2014, 50 (4), pp.2850 - 2873. (10.1002/2013WR015182)
  DOI : 10.1002/2013WR015182
• On the maximum time step in weakly compressible SPH
  
  • Violeau Damien
  • Leroy Agnès
  Journal of Computational Physics, Elsevier, 2014, 256, pp.388-415. In the SPH method for viscous fluids, the time step is subject to empirical stability criteria. We proceed to a stability analysis of the Weakly Compressible SPH equations using the von Neumann approach in arbitrary space dimension for unbounded flow. Considering the continuous SPH interpolant based on integrals, we obtain a theoretical stability criterion for the time step, depending on the kernel standard deviation, the speed of sound and the viscosity. The stability domain appears to be almost independent of the kernel choice for a given space discretisation. Numerical tests show that the theory is very accurate, despite the approximations made. We then extend the theory in order to study the influence of the method used to compute the density, of the gradient and divergence SPH operators, of background pressure, of the model used for viscous forces and of a constant velocity gradient. The influence of time integration scheme is also studied, and proved to be prominent. All of the above theoretical developments give excellent agreement against numerical results. It is found that velocity gradients almost do not affect stability, provided some background pressure is used. Finally, the case of bounded flows is briefly addressed from numerical tests in three cases: a laminar Poiseuille flow in a pipe, a lid-driven cavity and the collapse of a water column on a wedge.
• Wave basin experiments with large wave energy converter arrays to study interactions between the converters and effects on other users in the sea and the coastal area
  
  • Stratigaki V.
  • Troch P.
  • Stallard T.
  • Forehand D.
  • Kofoed J.P.
  • Folley M.
  • Benoit M.
  • Babarit A.
  • Kirkegaard J.
  Energies, MDPI, 2014, 7 (2), pp.701-734. Experiments have been performed in the Shallow Water Wave Basin of DHI (Hørsholm, Denmark), on large arrays of up to 25 heaving point absorber type Wave Energy Converters (WECs), for a range of geometric layout configurations and wave conditions. WEC response and modifications of the wave field are measured to provide data for understanding WEC array interactions and to evaluate array interaction numerical models. Each WEC consists of a buoy with a diameter of 0.315 m and power take-off (PTO) is modeled by realizing friction based energy dissipation through damping of the WEC’s motion. Wave gauges are located within and around the WEC array. Wave conditions studied include regular, polychromatic, long- and short-crested irregular waves. A rectilinear arrangement of WEC support structures is employed such that several array configurations can be studied. In this paper, the experimental arrangement and the obtained database are presented. Also, results for wave height attenuation downwave a rectilinear array of 25 heaving WECs are presented, for the case of irregular waves. Up to 16.3% and 18.1% (long-crested) and 11.2% and 18.1% (short-crested waves) reduction in significant wave height is observed downwave the WEC array, for the radiated wave field only and for the combination of incident-diffracted-radiated (perturbed) wave field, respectively. Using spectra at different locations within and around the array, the wave field modifications are presented and discussed. (10.3390/en7020701)
  DOI : 10.3390/en7020701
• Large eddy simulation of sediment transport over rippled beds
  
  • Harris Jeffrey
  • Grilli S. T.
  Nonlinear Processes in Geophysics, European Geosciences Union (EGU), 2014, 21 (6), pp.1169-1184. (10.5194/npg-21-1169-2014)
  DOI : 10.5194/npg-21-1169-2014
• A new model for shallow viscoelastic free-surface flows forced by gravity on rough inclined bottom
  
  • Boyaval Sébastien
  ESAIM: Proceedings, EDP Sciences, 2014, 45, pp.108 - 117. A thin-layer model for shallow viscoelastic free-surface gravity flows on slippery topogra-phies around a flat plane has been derived recently in [Bouchut-Boyaval, M3AS (23) 2013]. We show here how the model can be modified for flows on rugous topographies varying around an inclined plane. The new reduced model extends the scope of one derived in [Bouchut-Boyaval, M3AS (23) 2013]. It is one particular thin-layer model for free-surface gravity flows among many ones that can be formally derived with a generic unifying procedure. Many rheologies and various shallow flow regimes have already been treated within a single unified framework in [Bouchut-Boyaval, HAL-ENPC (00833468) 2013]. The initial full model used here as a starting point is however a little different to one used in [Bouchut-Boyaval, HAL-ENPC (00833468) 2013], although the new thin-layer model is very similar to the one derived therein. Precisely, here, the bulk dissipation (due to e.g. viscosity) is neglected from the beginning, like in [Bouchut-Boyaval, M3AS (23) 2013]. Moreover, unlike in [Bouchut-Boyaval, HAL-ENPC (00833468) 2013], we perform here numerical simulations. The interest of the extension is illustrated in a physically interesting situation where new stationary solutions exist. To that aim, the Finite-Volume method proposed in [Bouchut-Boyaval, M3AS (23) 2013] needs to be modified, with an adequate discretization of the new source terms. Interestingly, we can also numerically exhibit an apparently new kind of "roll-wave" solution.
• A two-step framework for over-threshold modelling of environmental extremes
  
  • Bernardara P.
  • Mazas F.
  • Kergadallan X.
  • Hamm L.
  Natural Hazards and Earth System Sciences, Copernicus Publ. / European Geosciences Union, 2014, 14 (3), pp.635-647. (10.5194/nhess-14-635-2014)
  DOI : 10.5194/nhess-14-635-2014
• Unified semi-analytical wall boundary conditions applied to 2-D incompressible SPH
  
  • Leroy Agnès
  • Violeau Damien
  • Ferrand Martin
  • Kassiotis Christophe
  Journal of Computational Physics, Elsevier, 2014, 261, pp.106-129. This work aims at improving the 2-D incompressible SPH model (ISPH) by adapting it to the unified semi-analytical wall boundary conditions proposed by Ferrand et al. [10]. The ISPH algorithm considered is as proposed by Lind et al. [25], based on the projection method with a divergence-free velocity field and using a stabilising procedure based on particle shifting. However, we consider an extension of this model to Reynolds-Averaged Navier-Stokes equations based on the k- turbulent closure model, as done in [10]. The discrete SPH operators are modified by the new description of the wall boundary conditions. In particular, a boundary term appears in the Laplacian operator, which makes it possible to accurately impose a von Neumann pressure wall boundary condition that corresponds to impermeability. The shifting and free-surface detection algorithms have also been adapted to the new boundary conditions. Moreover, a new way to compute the wall renormalisation factor in the frame of the unified semi-analytical boundary conditions is proposed in order to decrease the computational time. We present several verifications to the present approach, including a lid-driven cavity, a water column collapsing on a wedge and a periodic schematic fish-pass. Our results are compared to Finite Volumes methods, using Volume of Fluids in the case of free-surface flows. We briefly investigate the convergence of the method and prove its ability to model complex free-surface and turbulent flows. The results are generally improved when compared to a weakly compressible SPH model with the same boundary conditions, especially in terms of pressure prediction. (10.1016/j.jcp.2013.12.035)
  DOI : 10.1016/j.jcp.2013.12.035
• Code-coupling strategy for efficient development of computer software in multiscale and multiphysics nonlinear evolution problems in computational mechanics
  
  • Ibrahimbegovic Adnan
  • Niekamp Rainer
  • Kassiotis Christophe
  • Markovic Damijan
  • Matthies Hermann G.
  Advances in Engineering Software, Elsevier, 2014, 72, pp.8-17. (10.1016/j.advengsoft.2013.06.014)
  DOI : 10.1016/j.advengsoft.2013.06.014
• The differential production cross section of the phi(1020) meson in sqrt(s)=7 TeV pp collisions measured with the ATLAS detector
  
  • Aad G.
  • Albrand S.
  • Andrieux M.L.
  • Buat Q.
  • Clement B.
  • Collot J.
  • Crépé-Renaudin S.
  • Dechenaux B.
  • Delemontex T.
  • Delsart P.A.
  • Gabaldon C.
  • Genest M.H.
  • Hostachy J.Y.
  • Laisne E.
  • Ledroit-Guillon F.
  • Lleres A.
  • Lucotte A.
  • Malek F.
  • Stark J.
  • Sun X.
  • Trocmé B.
  • Wang J.
  • Weydert C.
  • Biscarat C.
  • Cogneras E.
  • Rahal G.
  • Boumediene D.
  • Busato Emmanuel
  • Calvet D.
  • Calvet S.
  • Camacho Toro Reina Coromoto
  • Cinca Diane
  • Donini J.
  • Febbraro R.
  • Ghodbane N.
  • Gris Ph.
  • Guicheney C.
  • Liao H.
  • Pallin D.
  • Paredes Hernández Daniela
  • Podlyski F.
  • Santoni C.
  • Vazeille F.
  • Abdel Khalek S.
  • Andari N.
  • Arnault C.
  • Augé E.
  • Barrillon P.
  • Benoit M.
  • Binet S.
  • Bourdarios C.
  • de La Taille C.
  • de Vivie de Regie J.B.
  • Duflot L.
  • Escalier M.
  • Fayard L.
  • Fournier D.
  • Grivaz J.-F.
  • Henrot-Versillé S.
  • Hrivnac J.
  • Iconomidou-Fayard L.
  • Idarraga J.
  • Kado M.
  • Lorenzo Martinez N.
  • Matricon P.
  • Niedercorn F.
  • Poggioli L.
  • Puzo P.
  • Renaud A.
  • Rousseau D.
  • Rybkin G.
  • Sauvan J.B.
  • Schaarschmidt J.
  • Schaffer A.C.
  • Scifo E.
  • Serin L.
  • Simion S.
  • Tanaka R.
  • Teinturier M.
  • Tran H.L.
  • Veillet J.J.
  • Wicek F.
  • Zerwas D.
  • Zhang Zhiqing
  • Aoun S.
  • Bee C.P.
  • Bertella C.
  • Bousson N.
  • Clémens J. C.
  • Coadou Y.
  • Djama F.
  • Etienne F.
  • Feligioni L.
  • Hoffmann D.
  • Hubaut F.
  • Knoops E. B. F. G.
  • Le Guirriec E.
  • Li B.
  • Maurer J.
  • Monnier E.
  • Nagai Y.
  • Odier J.
  • Pralavorio P.
  • Rozanov A.
  • Talby M.
  • Tannoury N.
  • Tiouchichine E.
  • Tisserant S.
  • Toth J.
  • Touchard F.
  • Vacavant L.
  • Berger N.
  • Delmastro M.
  • Di Ciaccio L.
  • Doan T.K.O.
  • Elles S.
  • Goy C.
  • Hryn'Ova T.
  • Jézéquel S.
  • Keoshkerian H.
  • Lafaye R.
  • Leveque J.
  • Lombardo V.P.
  • Massol N.
  • Petit E.
  • Przysiezniak H.
  • Sauvage G.
  • Sauvan E.
  • Schwoerer M.
  • Todorov T.
  • Wingerter-Seez I.
  • Zitoun R.
  • Simard O.
  European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2014, 74, pp.2895. A measurement is presented of the phi to K+K- production cross section at sqrt(s) = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 mub-1, collected with the ATLAS experiment at the LHC. Selection of phi(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, pTphi, and rapidity, |yphi|, of the phi(1020) meson in the fiducial region 500 < pTphi< 1200 MeV, |yphi| < 0.8, kaon pTK> 230 MeV and kaon momentum pK< 800 MeV.The integrated phi(1020)-meson production cross section in this fiducial range is measured to be s(phi K+K-) = 570 pm 8 (stat) pm 66 (syst) pm 20 (lumi) mub. (10.1140/epjc/s10052-014-2895-2)
  DOI : 10.1140/epjc/s10052-014-2895-2
• A Lagrangian/Eulerian oil spill model for continental waters
  
  • Goeury Cédric
  • Hervouet Jean-Michel
  • Baudin-Bizien Isabelle
  • Thouvenel François
  Journal of Hydraulic Research, Taylor & Francis, 2014, 52 (1), pp.36-48. (10.1080/00221686.2013.841778)
  DOI : 10.1080/00221686.2013.841778
• Hydrodynamic modeling and diffusion of the pollutant
  
  • Muttin Frédéric
  • Ricchiuto Mario
  • Mostefaoui Imene Meriem
  • Kirane Mokhtar
  • Goeury Cédric
  • Hervouet J. M.
  , 2014.
• An unstructured finite volume technique for the 3D Poisson equation on arbitrary geometry using a <i>σ</i> -coordinate system: An unstructured finite volume technique for the 3D Poisson equation on arbitrary geometry using a <i>σ</i> -coordinate system
  
  • Zapata Miguel Uh
  • van Bang Damien Pham
  • Nguyen Kim Dan
  International Journal for Numerical Methods in Fluids, Wiley, 2014, 76 (10), pp.611-631. (10.1002/fld.3945)
  DOI : 10.1002/fld.3945
• The effects of kinetic sorting on sediment mobility on steep slopes: GRAIN SORTING ON STEEP SLOPES
  
  • Bacchi Vito
  • Recking Alain
  • Eckert Nicolas
  • Frey Philippe
  • Piton Guillaume
  • Naaim Mohamed
  Earth Surface Processes and Landforms, Wiley, 2014, 39 (8), pp.1075-1086. In poorly mobile static armour, sorting is usually considered the result of hiding/exposure effects.We called this effect "static sorting" in opposition to very efficient grain-to-grain mechanisms produced by a mobile mixture, called "kinetic sorting". We hypothesized that kinetic sorting can be an important contributor to the morphodynamics of mountain streams and attempted to demonstrate this with new flume experiments. Two long runs were produced with natural poorly sorted sediments, and with transport stages of the coarse fraction (defined by the ratio between the shear stress and the critical shear stress for transport), smaller and higher than 1, respectively. Both runs produced an efficient transfer downstream of the injected material, but with a major difference: the first run (no kinetic sorting) produced permanent armour figuring clusters, akin to what has already been observed in similar experiments; the second run (with kinetic sorting) also produced bed armouring, but this armour was periodically totally destroyed, leading to substantial bed erosion. This phenomenon was explained by kinetic sorting, the effects of which are to produce an efficient downward migration of fine materials and bed surface armouring. The consequence is that fine materials are hidden to the flow during aggradation, allowing the slope to attain values much steeper than would have been expected at equilibrium for the mixture. However, whereas the surface armouring tends to stabilize the bed, construction of a layer of fine sediments at the subsurface also contributes to making it very unstable. These two contradictory effects explain the complex bed behaviours and the existence of very large bedload and slope fluctuations. (10.1002/esp.3564)
  DOI : 10.1002/esp.3564
• Comparaison de différentes méthodes d'estimation des niveaux extrêmes en site à fort et à faible marnage
  
  • Andreewsky Marc
  • Kergadallan Xavier
  • Bernardara Pietro
  • Benoit Michel
  • Gaufres Pierre
  • Trmal Céline
  La Houille Blanche - Revue internationale de l'eau, EDP Sciences, 2014 (4), pp.26-36. (10.1051/lhb/2014035)
  DOI : 10.1051/lhb/2014035
• Guest Editors' note
  
  • El Kadi Abderrezzak Kamal
  • Abad Jorge D.
  • Langendoen Eddy J.
  Journal of Hydro-environment Research, Elsevier, 2014, 8 (2), pp.75-76. (10.1016/j.jher.2014.05.002)
  DOI : 10.1016/j.jher.2014.05.002
• Numerical simulation of 3D free surface flows, with multipleincompressible immiscible phases. Applications to impulse waves
  
  • James Nicolas
  • Caboussat Alexandre
  • Boyaval Sébastien
  • Picasso M.
  International Journal for Numerical Methods in Fluids, Wiley, 2014, pp.00:1–24. A numerical method for the solution to the density-dependent incompressible Navier-Stokes equationsmodeling the flow of N immiscible incompressible liquid phases with a free surface is proposed. It allows tomodel the flow of an arbitrary number of liquid phases together with an additional vacuum phase separatedwith a free surface. It is based on a volume-of-fluid (VOF) approach involving N indicator functions (one perphase, identified by its density) that guarantees mass conservation within each phase. An additional indicatorfunction for the whole liquid domain allows to treat boundary conditions at the interface between the liquiddomain and a vacuum. The system of partial differential equations is solved by implicit operator splitting ateach time step: first, transport equations are solved by a forward characteristics method on a fine Cartesiangrid to predict the new location of each liquid phase ; second, a generalized Stokes problem with a density-dependent viscosity is solved with a finite element method on a coarser mesh of the liquid domain. A novelalgorithm ensuring the maximum principle and limiting the numerical diffusion for the transport of the Nphases is validated on benchmark flows. Then, we focus on a novel application, and compare the numericaland physical simulations of impulse waves, i.e. waves generated at the free surface of a water basin initiallyat rest after the impact of a denser phase. A particularly useful application in hydraulic engineering is topredict the effects of a landslide-generated impulse wave in a reservoir. (10.1002/fld.3967)
  DOI : 10.1002/fld.3967
• Application de la méthode LSPIV pour la mesure de champs de vitesse et de débits de crue sur modèle réduit et en rivière
  
  • Hauet A.
  • Jodeau M.
  • Le Coz J.
  • Marchand B.
  • Die Moran A.
  • Le Boursicaud R.
  • Dramais Guillaume
  La Houille Blanche - Revue internationale de l'eau, EDP Sciences, 2014, 3, pp.16-22. La technique LSPIV (Large Scale Particle Image Velocimetry) permet de mesurer les vitesses de surface d'un écoulement par analyse de séquence d'images. Pour faciliter l'application opérationnelle de la méthode, un logiciel, Fudaa-LSPIV, a été développé par la société DeltaCAD dans le cadre d'une collaboration entre EDF et Irstea. Deux applications en laboratoire et en rivière sont présentées : (i) couplée avec des mesures de hauteur d'eau et de bathymétries, la LSPIV a permis d'estimer des paramètres de Shields sur le modèle physique à fond mobile du Vieux-Rhin ; (ii) le logiciel a été utilisé pour procéder à des analyses de sensibilité pour paramétrer ainsi au mieux les stations LSPIV de mesure de débit en crue de rivières cévenoles. (10.1051/lhb/2014024)
  DOI : 10.1051/lhb/2014024