Structured Input-Output Analysis of Turbulent Flows over Riblets

Talha Mushtaq, Mitul Luhar, Maziar S. Hemati

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    1 Scopus citations

    Abstract

    This paper applies structured input-output (I/O) methods to analyze turbulent channel flows over riblets. Structured I/O provides a reduced-complexity framework for accounting for the nonlinear terms in the Navier-Stokes equations, thus providing a greater degree of fidelity in the analysis of nonlinear flows than the related linear I/O and resolvent-based analysis techniques We show that structured I/O is capable of predicting I/O gains relevant to the nonlinear flow physics as well as the associated modes that reveal the underlying instability mechanisms driving turbulent flows over riblets. Particularly, we show that the structured I/O analysis highlights dominant inst abilities associated with the lift-up mechanism, Tollmien-Schlichting waves, and Kelvin-Helmholtz-type vortices for the turbulent channel flow model. The associated wave numbers identified for these instabilities are physically consistent with the results found in prior DNS studies. Furthermore, we show that the rectangular and triangular riblets analyzed in this study minimize the I/O gains of the near-wall cycle, leading to the emergence of new smaller-scale structures that have been highlighted in previous DNS studies. Results and findings are reported and discussed for turbulent channel flows at Reτ=180 with smooth-walls and both rectangular and triangular riblet patterning.

    Original languageEnglish (US)
    Title of host publicationAIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2023
    PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
    ISBN (Print)9781624107047
    DOIs
    StatePublished - 2023
    EventAIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2023 - San Diego, United States
    Duration: Jun 12 2023Jun 16 2023

    Publication series

    NameAIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2023

    Conference

    ConferenceAIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2023
    Country/TerritoryUnited States
    CitySan Diego
    Period6/12/236/16/23

    Bibliographical note

    Publisher Copyright:
    © 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

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