Dynamic structuring and mixing efficiency in rapidly rotating shear layers

Bernard J. Geurts, Darryl D. Holm

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    Abstract

    Flow evolution in a rotating mixing layer is investigated using direct and large-eddy simulation. The mixing layer rotates about a fixed vertical axis perpendicular to the plane of its mean initial shear. The rotating mixing layer forms oscillatory large-scale columnar structures and rapid horizontal flow-reversals. The frequency of these oscillations varies approximately inversely with the Rossby number, $Ro$. At low $Ro$ vertical mixing of a passive scalar is strongly reduced. This is quantified by investigating the evolution of level-sets of the scalar field. The surface-area of the level-sets remains virtually constant even at modest rotation rates. More localized motions are less affected by rotation and yield comparatively high levels of surface-wrinkling. Rotation effects are accurately predicted in large-eddy simulations that involve the dynamic eddy-viscosity model or the LANS-$\alpha$ or Leray regularization models. The small-scale variability is best preserved when using the LANS-$\alpha$ formulation.
    Original languageEnglish
    Title of host publicationDirect and Large-Eddy Simulation VI
    EditorsEric Lamballais, Rainer Friedrich, Bernard J. Geurts, Olivier Métais
    Place of PublicationDordrecht
    PublisherSpringer
    Pages249-256
    Number of pages8
    ISBN (Electronic)978-1-4020-5152-4
    ISBN (Print)978-1-4020-4909-5
    DOIs
    Publication statusPublished - Oct 2006
    Event6th ERCOFTAC Workshop on Direct and Large-Eddy Simulation VI, DLES 2005 - University of Poitiers, Poitiers, France
    Duration: 12 Sep 200514 Sep 2005
    Conference number: 6

    Publication series

    NameERCOFTAC series
    PublisherSpringer
    Volume10
    ISSN (Print)1382-4309
    ISSN (Electronic)2215-1826

    Conference

    Conference6th ERCOFTAC Workshop on Direct and Large-Eddy Simulation VI, DLES 2005
    Abbreviated titleDLES
    CountryFrance
    CityPoitiers
    Period12/09/0514/09/05

    Keywords

    • Direct numerical simulation
    • Rotation rate
    • Passive scalar
    • Momentum thickness
    • Rossby number

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