68th Annual Meeting of the APS Division of Fluid Dynamics (November 22, 2015 — November 24, 2015)

P0007: A graphical representation of the spectral proper orthogonal decomposition

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Authors

• Moritz Sieber, Chair of Fluid Dynamics, Hermann-Föttinger-Institut, Technische Universität Berlin, Berlin, Germany
• Alexander Kuhn, Deptartment of Visual Data Analysis, Zuse Institute Berlin, Berlin, Germany
• Hans-Christian Hege, Deptartment of Visual Data Analysis, Zuse Institute Berlin, Berlin, Germany
• C. Oliver Paschereit, Chair of Fluid Dynamics, Hermann-Föttinger-Institut, Technische Universität Berlin, Berlin, Germany
• Kilian Oberleithner, Chair of Fluid Dynamics, Hermann-Föttinger-Institut, Technische Universität Berlin, Berlin, Germany

DOI: https://doi.org/10.1103/APS.DFD.2015.GFM.P0007

In this poster, the properties of the newly introduced spectral proper orthogonal decomposition (SPOD) are demonstrated from a visualization point of view. The SPOD is a method to decompose time-resolved data from turbulent flows. It is based on classic proper orthogonal decomposition (POD) with an additional temporal constraint. The new method allows for a much better separation of coherent structures due to a clean spectral separation of phenomena. The filter operation embedded in this method allows for continuous fading from the classic POD to Fourier mode decomposition. For one flow configuration this transition from the modal sparsity of POD to the spectral purity of Fourier mode decomposition is visualized in a comprehensible manner. This representation condenses the huge dynamic range of a turbulent flow into a compact modal representation. It further demonstrates how the increasing spectral restriction of the SPOD first separates individual phenomena into modal contributions and later disperses them into the Fourier spectrum.  The visual presentation of the SPOD allows a quick conception of its qualities and furthermore provides new insight into the dynamics of turbulent flows.