Publications

2015

• Coupling 3-D Navier Stokes and 1-D Shallow Water
  
  • Daou Mehdi Pierre
  • Blayo Eric
  • Rousseau Antoine
  • Bertrand Olivier
  • Tayachi Manel
  • Coulet Christophe
  • Goutal Nicole
  La Houille Blanche - Revue internationale de l'eau, EDP Sciences, 2015 (6), pp.29-33. The present work addresses the problem of coupling hydrodynamical models with different spatial dimensions, which can be used in order to reduce the computational cost of river numerical models. We show that this problem can be tackled quite efficiently by designing a simple algorithm using techniques borrowed from domain decomposition theory. This algorithm is non intrusive, i.e. allows using existing numerical models with very few modifications. The method is illustrated on an academic test-case, namely a free surface flow in a bend-shaped channel. A 3-D Navier-Stokes model is coupled with a 1-D shallow water model, and results are compared to those obtained in a fully 3-D case. It is shown that the coupling algorithm provides an accurate solution, which can be improved thanks to an iterative algorithm (Schwarz method). This study is performed using the Mascaret-Telemac system. (10.1051/lhb/20150065)
  DOI : 10.1051/lhb/20150065
• Dynamics of nonmigrating mid-channel bar and superimposed dunes in a sandy-gravelly river (Loire River, France)
  
  • Wintenberger Coraline
  • Rodrigues Stéphane
  • Claude Nicolas
  • Jugé Philippe
  • Bréhéret Jean-Gabriel
  • Villar Marc
  Geomorphology, Elsevier, 2015, 248, pp.185-204. A field study was carried out to investigate the dynamics during floods of a nonmigrating, mid-channel bar of the Loire River (France) forced by a riffle and renewed by fluvial management works. Interactions between the bar and superimposed dunes developed from an initial flat bed were analyzed during floods using frequent mono- and multibeam echosoundings, Acoustic Doppler Profiler measurements, and sediment grain-size analysis. When water left the bar, terrestrial laser scanning and sediment sampling documented the effect of post-flood sediment reworking. During floods a significant bar front elongation, spreading (on margins), and swelling was shown, whereas a stable area (no significant changes) was present close to the riffle. During low flows and falling limbs of floods, intense sediment reworking on the top of the bar and lateral scouring occurred. Hydrological variations controlled the sediment supply (in terms of phasing, quantity, and grain size) delivered by surrounding channels during floods and thus superimposed dune development. Their development was also linked to the sediment availability (armor layers, riffle proximity). Their relatively constant height highlights a preferential adaptation on dune length during floods. The role of each morphological forcing parameters (riffle vs. channel widening and curvature) on the bar dynamics and evolution is stage dependent; the shape, dynamics, and long-term morphological evolution of the bar and of the river reach (surrounding islands, channel translation) mainly depends on the presence of the natural riffle. (10.1016/j.geomorph.2015.07.032)
  DOI : 10.1016/j.geomorph.2015.07.032
• DNS and LES of 3-D wall-bounded turbulence using Smoothed Particle Hydrodynamics
  
  • Mayrhofer A.
  • Laurence D.
  • Rogers B. D.
  • Violeau D.
  Computers and Fluids, Elsevier, 2015, 115, pp.86-97. (10.1016/j.compfluid.2015.03.029)
  DOI : 10.1016/j.compfluid.2015.03.029