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Published byBilal Gamby Modified about 1 year ago

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1 High performance Computing Applied to a Saltwater Intrusion Numerical Model E. Canot IRISA/CNRS J. Erhel IRISA/INRIA Rennes C. de Dieuleveult IRISA/INRIA Rennes

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2 Outline Context Model and Test Cases Coupled Model Test Cases : Henry and Elder Parallel performances Presentation Results Conclusion

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3 Context Effect of pumping in coastal aquifers Necessity to predict the evolution of the water supply. Context

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4 Presentation of the software Based on TVDV-2D software developped at IMFS in Strasbourg Simulation of density driven coupled flow and transport in a porous media Originally sequential Coupled Model

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5 Model FLOW TRANSPORTconvection dispersion Coupled Model

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6 Strong Coupling Concentration Time n FLOWTRANSPORT Velocity Density Time n+1 Coupled Model

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7 Henry Stable test case Test Cases

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8 Elder Unstable test case Test Cases

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9 First parallel version (v1) Parallel performances Parallel linear solvers

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10 Parallel sparse solver Use of MUMPS (« MUltifrontal Massively Parallel Solver »), a free package for solving linear systems of equations Ax=b Adapted for sparse unsymmetric, and symmetric definite positive matrices. Parallel performances

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11 Global parallelisation (v2) Partitioning mesh thanks to METIS, a free package for partitioning graphs, meshes and for producing fill reducing orderings for sparse matrices. Partitioning example with 5 parts Better data distribution. Parallel performances

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12 Time step number 1 processor2 processors Iteration number Time step (in day) Iteration number Time step (in day) 1101/4101/4 2 to 7121/4121/4 826 (no convergence) 1/4111/4 1/81/4 Results Due to the convergence criterion Elder (mesh 256x160) Sensitivity to convergence criterion

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13 Sensitivity to convergence criterion Results Elder (mesh 256x160), time step number 8

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14 Wall clock (in seconds) Number of processors Results Results for the first version (v1) Henry (mesh 510x254)

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15 Number of processors Results Results for the second version (v2) Wall clock (in seconds) Henry (mesh 510x254)

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16 Conclusion - Perspectives 3D geometry Adaptative mesh Improved coupling Conclusion

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