Empirical mode decomposition has been shown to be a valuable data analysis tool in a wide array of technical fields, and it has recently emerged as a useful technique for studying complex fluid flows. This technique is useful for separating relevant unsteady spatiotemporal scales from a signal through an adaptive, iterative data-processing algorithm. Traditionally, empirical mode decomposition has been used to study time-dependent single-dimensional signals, though it can also be useful for studying multidimensional flowfield data. For the current study, unsteady velocity measurements were acquired across the initial development region of a turbulent-plane mixing layer using time-resolved particle image velocimetry. Empirical mode decomposition was applied to the resulting velocity field measurements to decompose the flowfield into several unsteady modes. Single-dimensional empirical mode decomposition was used to understand the time-frequency behavior of the flow associated with the formation and pairing process of large-scale vortical structures. The resulting spectrogram clearly displayed a periodic influence of large-scale vortex structures produced by the Kelvin–Helmholtz instability, which also exhibited a phase relationship with the vortex pairing mechanism. A multidimensional empirical mode decomposition analysis was also conducted, which allowed the unsteady velocity field to be decomposed into scale-based modes with dependence on x, y, and t dimensions. This analysis allowed the influence of small-scale turbulent structures within the flowfield to be separated from those associated with large-scale vortical structures produced by the Kelvin–Helmholtz instability.


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    Titel :

    Separation of Unsteady Scales in a Mixing Layer Using Empirical Mode Decomposition



    Erschienen in:

    Erscheinungsdatum :

    2017




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch


    Schlagwörter :

    Klassifikation :

    BKL:    55.50 Luftfahrzeugtechnik / 55.60 Raumfahrttechnik / 55.60 / 50.93 / 55.50 / 50.93 Weltraumforschung
    Lokalklassifikation TIB:    770/7040



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