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Large Scale Simulation of Turbulence Using a Hybrid Spectral/Finite Difference Solver



Performing Direct Numerical Simulation (DNS) of turbulence on large-scale systems (offering more than 104 cores) has become a challenge in high performance computing. The computer power increase allows now to solve flow problems on large grids (with close to 109 nodes). Moreover these large scale simulations can be performed on non-homogeneous turbulent flows. A reasonable amount of time is needed to converge statistics if the large grid size is combined with a large number of cores. To this end we developed a Navier-Stokes solver, dedicated to situations where only one direction is heterogeneous, and particularly suitable for massive par- allel architecture. Based on an hybrid approach spectral/finite-difference, we use a volumetric decomposition of the domain to extend the FFTs computation to a large number of cores. Scalability tests using up to 32K cores as well as preliminary results of a full simulation are presented.

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