On low-dimensional modeling of channel turbulence

Ahmet Omurtag, Larry Sirovich

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

1 Scopus citations

Abstract

We investigate a sequence of low dimensioned models of turbulent channel flows. These models are based on the extraction of the Karhunen-Loève (KL) elgenfunctions from a large scale simulation In a wide channel with R*. = 180 (based, on the friction velocity). KL eigenfunctions provide an optimal coordinate system in which to represent the dynamics of the turbulent flow. The hierarchy of KL modes Identifies the most energetic independent phenomena in the system. A series of Galerkin projections is then used to derive a dynamical approximation to flows. In order to capture essential aspects of the flow in a low dimensional system, a careful selection of modes is carried out. The resulting models satisfy momentum and energy conservation as well as yielding the amount of viscous dissipation found in the exact system. Their dynamics includes modes which characterize the flux, rolls, and propagating waves. Unlike previous treatments the instantaneous stream wise flow Is time dependent and represented by KL flux modes. The rolls correspond to the streaks observed in experiments In the viscous sublayer. Propagating waves which first appear In the model flow at low Reynolds number (R*~ 60) persist through the chaotic regime that appears as the Reynolds number is Increased. Statistical measures of the chaotic flows which have been generated by the models compare favorably with those found in full scale simulations.

Original languageEnglish (US)
Title of host publication29th AIAA Fluid Dynamics Conference
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
Pages1-7
Number of pages7
ISBN (Print)9780000000002
DOIs
StatePublished - 1998
Event29th AIAA Fluid Dynamics Conference - Albuquerque, United States
Duration: Jun 15 1998Jun 18 1998

Other

Other29th AIAA Fluid Dynamics Conference
CountryUnited States
CityAlbuquerque
Period6/15/986/18/98

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Aerospace Engineering

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