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PROPER ORTHOGONAL DECOMPOSITION ANALYSIS OF A PUFF IN A PIPE

David Moxey
Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK

Yuri Feldman
Department of Mechanical Engineering, Ben-Gurion University, Beersheva 84105, Israel

Paris Perdikaris
Division of Applied Mathematics, Brown University, Providence, RI 02912, USA

Joseph Insley
Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, IL 60439, USA

Alexander Yakhot
Mechanical and Aerospace Engineering Princeton University; Department of Mechanical Engineering, Ben-Gurion University, Beersheva 84105, Israel

Spencer J. Sherwin
Department of Aeronautics, Imperial College London, Prince Consort Rd, London, SW7 2BY, UK

George Em Karniadakis
Division of Applied Mathematics Brown University Providence, RI 02912, USA

Abstrakt

We have performed direct numerical simulations of transitional turbulence in pipe flow for Re=2,250. The results confirm the existence of a spatio-temporal intermittency when turbulence is localized in a puff convected downstream. To analyze the turbulence, we follow a turbulent puff by a 3D moving-window centered at the location of the maximum total energy of transverse (turbulent) motion. The flow field data collected over 6,000 time instances (snapshots) have been analyzed by Proper Orthogonal Decomposition (POD) and used for identifying vortical structures. The presence of large-scale structures in a puff has been found by time-averaging of the cross-sectional turbulent velocity field and confirmed by POD analysis and by applying the Q- and λ2-criteria.