EPI Gamma 1996-2000-2004-2008 AND Gamma3 PROPOSAL P.L. George & al. Evaluation, 17-18-19 March 2009 Context and chronology. Gamma : 1996-2000-2004-2008. Gamma3 proposal. A few images.
Context and chronology Finite Element and Finite Volume. PDE. 70s: First automatic mesh generation algorithms for arbitrary domains. 2D ADV (J.A. George, PhD Stanford). 1980: F . Hermeline PhD, P6. Delaunay 2D and 3D. 80s: First automatic tet meshers for arbitrary domains. “Octree” (RPI, Troy, NY), Delaunay based (MSU, MS and Princeton, NJ) and ADV (Imperial College and Swansea, UK). 1985: Thompson Warsi Mastin , “Numerical grid generation” (Elsevier). 1985: Shamos Preparata, “Computational Geometry” (Springer-Verlag). 1987: J. Peraire & al. “3D adaptive remeshing” (notion of a metric). 1989: R. L¨ ohner “3D adaptive remeshing” (quality meshing). INRIA, EPI Modulef and Menusin , with P6 : Modulef library. 1990: P .L. G., “Automatic mesh generation” (Wiley). 1990: M.G. Vallet PhD, INRIA-P6. Anisotropic mesh generation 2D. 90s: INRIA designed (DRET grant) a Delaunay based tet mesher for arbitrary domains where the given surface mesh is preserved . 96: The Gamma EPI is created. 2 EPI Gamma
The Gamma EPI: 1996-2008. Main lines About 10 persons including 5 permanent positions. Automatic mesh generation methods (3D tet-hex, 2D1/2 tri-quad, 2D tri-quad). Mesh optimisation, mesh modification, mesh visualization, definition of data structures, ... First periods, topics are 100% devoted to mesh generation algorithms and methods and related software components. > Emphasis on 3D domains (blocking point at this time). > Then surface mesh generation methods (under estimated topics in general). > Still 2D methods for advanced cases. All of that results in a suite of software components. Diffusion via INRIA (and UTT) then Simulog and nowadays Dist` ene. 3 EPI Gamma
The Gamma EPI: 1996-2008. Main lines >>> 1996-2004 The know-how allows for numerical simulations within the EPI, other EPIs or made by industrial partners. This results in new challenges. >>> 2004-.... Indeed, it is no longer possible to work on mesh generation methods without considering the solver side and the concrete applications. Algorithms needed for mesh adaptation and adaptive computations require combining meshing methods, error estimators and solvers. This leads us to introduce a more important part in the solver side. It is no longer possible to look at the meshing side only , the risk being to miss the real life problems, to consider problems that are not really posed or purely academic cases. 3 EPI Gamma
The Gamma EPI: 1996-2008. Algorithms and theories Main keywords : 2D anisotropy == > surface (anisotropy cames from curvatures), 3D meshing (tets and hexes), 3D anisotropy (tets), Nanostructured materials, geometrical modelization, CAD surface modelization, topology, ridges, ... Metric and error estimate, Governed methods (size map or discrete metric field) (therefore == > mesh adaptation), Adaptive computation schemes, CFD solvers (Euler). Main choices for basic algorithms : Speed, robustness, validation by means of classical or orthogonal choices: Simple (subtle) data structures, bucket, random, non-random, cache default, no C ++ nor Matlab , no extended arithmetic, no external ressources, ... 4 EPI Gamma
The Gamma EPI: 1996-2008. Algorithms and theories Theoretical frame : the notion of a “unit mesh”, related to the fondamental notion of a metric. An abstract definition of the “mesh quality” related to the definition of adequate and application dependent metrics. error estimate based on the interpolation error (for various norms) and field interpolation with adequate properties. a theory about continuous meshes in multi-scale adaptation or goal oriented adaptation (objective functional). an octree dual based approach for hex meshing. extraction of CAD surface topology (skeleton). extraction of geometrical characteristics (lines) for parametric surface. a method for the geometric modelization for specific surfaces (nanostructures, molecules, ...). 4 EPI Gamma
The Gamma EPI: 1996-2008. Algorithms and theories Validation, a primordial concern of Gamma : blind validation using our own Data Base ( ≈ 100 Kdata), real life problems on industrial cases or via diverse contracts (EEC, competitivity clusters, ....), via master, PhD or post-doc. Collaborations : EPIs Smash and Tropics at Sophia-Antipolis, EPI Macs at Rocquencourt, laboratoire JL 2 at UPMC (P6), universit´ e de technologie de Troyes (UTT), universit´ e d’Ottawa, ´ ecole polytechnique f´ ed´ erale de Lausanne (EPFL). ONERA, Dassault Aviation (DA), Lectra, Lemma, Dist` ene and clusters or EEC contrats. 4 EPI Gamma
Software components, a key point of the EPI GHS3D and sons, classical or governed (iso or aniso) tet mesher 1 , Hexotic , full hex mesher, BLSURF , parametric surface mesher 2 , BLMOL , surface mesher for molecules, BL2D , 2D mesher 3 , Wolf , Euler and Navier-Stokes solver, SonicBoom , sonic boom solver, Metrix , construction of metric fields from E.E. and operations about metrics, Interpol , field transfer from mesh to mesh, Shrimp , domain partitionner, specific renumbering (vertices, elements, ...), the suite PPxxx , diverse tools for domain partitionning , mesh intersection, mesh correction, medit , mesh and solution visualization. Transfers via Dist` ene or directly (INRIA and/or UTT). 1Abaqus, Akka, Alcan, Armines, Cea, Cetim, Cnrs, Cocreate, Coretech, Cst, Edf, Eta, Kias, Plassotech, Pointwise, Robobat, Samtech, Sharc, Honda, Simpoe, Simulation works, Snecma, Soliworks, Synopsis, Technostar, Transvalor, Wias, Williams, ... 2Cea, Cnrs, DA, Edf, Emw, Lectra, Onera, Simpoe, ... 3Alcatel, Safran/Snecma, Nippon Steel! ... 5 EPI Gamma
Main achievements Books. 1996: P .L. G. and H. B. “Delaunay triangulation and meshing” (Hermes), 2000: P .F . and P .L. G. “Mesh generation” (Hermes), 2001: P .L. G. (eds), “Maillage et adaptation” (Hermes), 2008: P . F. and P .L. G. “Mesh generation” 2nd edition (ISTE and Wiley). PhD. 2002-2004: C. D. (PhD), 3D adaptation by means of local remeshing, 2004-2007: B. C. (PhD), parametric surface, cad, ridges extraction, 2005-2008: A. B. (PhD), nanostructured materials, geometric modelization, 2005-2008: A. L. (PhD), multi-scale adaptation and continuous meshes, 2006-....: E. R. (PhD), parametric surface, cad, topology, optimization, 2007-....: G. O. (PhD), ALE method. 6 EPI Gamma
Main achievements Papers. 1997: H.B. & al., “Delaunay mesh generation governed by metric specifications”, 1 and 2, FEAD. 1997: P .L. G., “Improvement on Delaunay based 3D automatic mesh generator”, FEAD. 2000: H.B., P .L. G. and P . L., “Parametric surface meshing using a combined advancing front generalized Delaunay approach”, IJNME. 2002: P .L. G. and H.B., “Ultimate robustness in meshing an arbitrary polyhedron”, IJNME. 2008: Y. Bourgault, M. Picasso, F. Alauzet and A. Loseille, On the use of anisotropic error estimators for the adaptative solution of 3-D inviscid compressible flows, IJNMF . 2008: F. Alauzet, High-Order method and mesh adaptation for Euler equation, IJNMF . 2008: F. Alauzet, S. Borel-Sandou, L. Daumas, A. Dervieux, Q. Dinh, S. Kleinveld, Loseille, Y. Mesri and G. Rog´ e, Multi-model and multi-scale optimization strategies. Application to sonic boom reduction, EJCM. 2008: C. Bennis, H. B. and N. Flandrin, 3D conforming power diagrams for radial LGR in CPG reservoir grids, EWC. 2008: B. Cl´ emenc ¸on, H. Borouchaki and P . Laug, Ridge extraction and its application to surface meshing, EWC. 2008: P . Laug, H. Borouchaki, A. Benabbou and J. Lu, Mod´ elisation g´ eom´ etrique de structures granulaires, CRAS. 2008: T. Grosges, H. Borouchaki and D. Barchiesi, New adaptive mesh development for accurate near-field enhancement computation, JM. 2007: P .L. George, H. Borouchaki, P .J. Frey, P . Laug and E. Saltel, Encyclopedia of Computational Mechanics, ch. 17, Mesh Generation and mesh adaptivity. 2007: F. Alauzet, P . Frey, P .L. George and B. Mohammadi, 3D transient fixed point mesh adaptation for time-dependent problems: Application to CFD simulations, JCP . 2007: A. Dervieux, Y. Mesri, F. Alauzet, A. Loseille, L. Hascoet and B. Koobus, Continuous mesh adaptation models for CFD, CFDJ. 7 EPI Gamma
Main achievements Papers (continued). 2006: F. Alauzet, X. Li, E. Seegyoung Seol and M.S. Shephard, Parallel anisotropic 3D mesh adaptation by mesh modification, EWC 2006: A. Cherouat, H. Borouchaki, K. Saanouni and P . Laug, Numerical methodology for metal forming processes using elastoplastic model with damage occurrence, JMST. 2005: P . Frey and F. Alauzet, Anisotropic mesh adaptation for CFD computations, CMAME. 2005: H. Borouchaki, P . Laug, A. Cherouat, K. Saanouni, Adaptive remeshing in large plastic strain with damage, IJNME. 2005: H. Borouchaki, J. Villard, P . Laug and P .L. George, Surface mesh enhancement with geometric singularities identification, CMAME. 2005: A. Cherouat, K. Saanouni, H. Borouchaki and P . Laug, Virtual metal forming with damage occurrence using adaptive remeshing, IJFP . 2004: P . Laug and H. Borouchaki, Curve linearization and discretization for meshing composite parametric surfaces, CNME. 2004: H. Borouchaki and P . Laug, Simplification of Composite Parametric Surface Meshes,EWC. 8 EPI Gamma
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