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Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids. Miriam Mehl Ionel Muntean, Tobias Neckel, Tobias Weinzierl Computer Science TU München. Why Cartesian Grids?. Numerical Efficiency. hierarchically structured Cartesian grids arbitrarily local adaptivity
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Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Miriam Mehl Ionel Muntean, Tobias Neckel, Tobias Weinzierl Computer Science TU München Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Why Cartesian Grids? Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Numerical Efficiency • hierarchically structured Cartesian grids • arbitrarily local adaptivity • full approximation schemes • efficient multigrid methods Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Hardware Efficiency ½ ½ -1 • cell-oriented operator evaluation • constant difference stencils • no neighbour relations • low storage Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Hardware Efficiency • Peano curve • processing order of grid cells • time locality of data access Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Hardware Efficiency • stacks as data structures • spatial locality of data access Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Hardware Efficiency • cache-misses 110% of minimum • runtime 5 times DiMe (regular grid) 3D Poisson • sphere, adaptive • 23,118,848dofs Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Flexibility • geometric adaptivity • Eulerian approach (marker-and-cell) • complicated changing geometries Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Accuracy • geometric adaptivity • cutting-cell methods • hierarchical operator generation • second order accuracy in geometry Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Physical Correctness • Verstappen, 2001: • symmetry requirements • energy and momentum conservation FEM: Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Physical Correctness • FEM-basis: u-v-coupled, piecewise linear • correct velocity interpolation • dynamical adaptivity, coupling surface Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Why Cartesian Grids? Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Numerical Results • Regular grid code F3F: • symmetry preserving FV discretisation • fully parallel • full 3D functionality • platforms up to now: • HLRB2 (SGI Altix 4700) • TU München Infinicluster (128 CPU Opteron) • Universität Stutgart Mozart (128 CPU Xeon cluster) Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Numerical Results Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Numerical Results • Adaptive grid code Peano: • 2D Navier-Stokes • parallel Poisson • platforms up to now: • HLRB2 (SGI Altix 4700) • TU München Infinicluster (128 CPU Opteron) • PC cluster Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Numerical Results • Free channel flow: Re=1111 • in preparation to DNS • boundary layer: adaptively refined Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München
Conclusion + Outlook • appropriateness of our approach • concept for adaptive grids: Navier-Stokes • Cartesian grids: applications • next steps: • fully functional 3D parallel adaptive NS-solver • refinement criteria for turbulent boundary layers • runtime optimisation on supercomputers Efficient Parallel Simulation of Fluid Dynamics on Cartesian Grids Computer Science, TU München