Publications

2016

• A second order residual based predictor–corrector approach for time dependent pollutant transport
  
  • Pavan Sara
  • Hervouët Jean-Michel
  • Ricchiuto Mario
  • Ata Riadh
  Journal of Computational Physics, Elsevier, 2016, 318, pp.122 - 141. 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 has to be considered in order to respect some important numerical properties at discrete level. Beyond the classical characteristics of the residual formulation presented in [1] and [2], we introduce the possibility to iterate the corrector step in order to improve the accuracy of the scheme. Another novelty is that the scheme is based on a precise monotonicity condition which guarantees the respect of the maximum principle. We thus end up with a scheme which is mass conservative, second order accurate and monotone. These properties are checked in the numerical tests, where the proposed approach is also compared to some finite volume schemes on unstructured grids. The results obtained show the interest in adopting the predictor corrector scheme for pollutant transport applications, where conservation of the mass, monotonicity and accuracy are the most relevant concerns. (10.1016/j.jcp.2016.04.053)
  DOI : 10.1016/j.jcp.2016.04.053
• A new open boundary formulation for incompressible SPH
  
  • Leroy Agnès
  • Violeau Damien
  • Ferrand Martin
  • Fratter Louise
  • Joly Antoine
  Computers & Mathematics with Applications, Elsevier, 2016, 72, pp.2417 - 2432. In this work a new formulation for inflow/outflow boundary conditions in an incompressible Smoothed Particles Hydrodynamics (ISPH) model is proposed. It relies on the technique of unified semi-analytical boundary conditions that was first proposed for wall boundary conditions in 2013, then extended to open boundaries in the framework of weakly-compressible SPH (WCSPH). An ISPH model relying on that formulation for solid boundaries was then proposed, which is the one considered here. It includes a buoyancy model for temperature effects and a k − turbulence closure. There are two main requirements for the imposition of open boundaries in ISPH: an algorithm to let particles enter and leave the domain, and the correct imposition of open boundary conditions on the fields. Regarding the algorithm for particles creation/destruction, it relies on the variation of mass of the particles located at the open boundaries. When the mass of such a particle reaches a threshold, a new particle is released. On the other hand, the imposition of open boundary conditions on the fields is done by prescribing the value of the boundary terms appearing in the semi-analytical formulation. The formulation was first validated in 2-D on a cut dam-break, a case of propagation of a solitary wave and a Creager weir. It was then extended to 3-D and tested on a 3-D circular pipe. A preliminary application case consisting of two connected pipes at different temperatures was then simulated. The results are promising since in all cases the fluid enters and leaves the domain as prescribed and generating none or very few reflected waves. (10.1016/j.camwa.2016.09.008)
  DOI : 10.1016/j.camwa.2016.09.008
• A database of validation cases for tsunami numerical modelling
  
  • Violeau Damien
  • Ata Riadh
  • Benoit Michel
  • Joly Antoine
  • Abadie Stéphane
  • Clous Lucie
  • Martin Medina Manuel
  • Morichon Denis
  • Chicheportiche Jérémie
  • Le Gal Marine
  • Gailler A.
  • Hebert Hélène
  • Imbert David
  • Kazolea Maria
  • Ricchiuto Mario
  • Le Roy Sylvestre
  • Pedreros Rodrigo
  • Rousseau Marie
  • Pons Kévin
  • Marcer Richard
  • Journeau Camille
  • Silva Jacinto R.
  , 2016. This work has been performed by a French national consortium within the framework of the national project 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 capabilities of 18 codes, solving various set of equations with different numerical methods. 14 test cases were defined from 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 and weaknesses of the models, to quantify the errors that these models may induce, to compare the various modelling methods, and to provide users with recommendations for practical studies. In this paper, 3 representative cases are selected and presented with an analysis of the results.
• Observations and modeling of San Diego beaches during El Niño
  
  • Doria André
  • Guza R.T.
  • O 'Reilly William C
  • Yates Marissa L.
  Continental Shelf Research, Elsevier, 2016, 124, pp.153-164. Subaerial sand levels were observed at five southern California beaches for 16 years, including notable El Niños in 1997–98 and 2009–10. An existing, empirical shoreline equilibrium model, driven with wave conditions estimated using a regional buoy network, simulates well the seasonal changes in subaerial beach width (e.g. the cross-shore location of the MSL contour) during non-El Niño years, similar to previous results with a 5-year time series lacking an El Niño winter. The existing model correctly identifies the 1997–98 El Niño winter conditions as more erosive than 2009–10, but overestimates shoreline erosion during both El Niños. The good skill of the existing equilibrium model in typical conditions does not necessarily extrapolate to extreme erosion on these beaches where a few meters thick sand layer often overlies more resistant layers. The modest over-prediction of the 2009–10 El Niño is reduced by gradually decreasing the model mobility of highly eroded shorelines (simulating cobbles, kelp wrack, shell hash, or other stabilizing layers). Over prediction during the more severe 1997–98 El Niño is corrected by stopping model erosion when resilient surfaces (identified with aerial imagery) are reached. The trained model provides a computationally simple (e.g. nonlinear first order differential equation) representation of the observed relationship between incident waves and shoreline change. (10.1016/j.csr.2016.05.008)
  DOI : 10.1016/j.csr.2016.05.008