Title: Anisotropy-invariant mapping of turbulence in a flow past an unswept airfoil at high angle of attack
Authors: Joviĉić, Nikola
Breuer, Michael 
Jovanović, J.
Language: eng
Issue Date: May-2006
Publisher: ASME
Document Type: Article
Journal / Series / Working Paper (HSU): Journal of Fluids Engineering, Transactions of the ASME
Volume: 128
Issue: 3
Page Start: 559
Page End: 567
Publisher Place: New York
Turbulence investigations of the flow past an unswept wing at a high angle of attack are reported. Detailed predictions were carried out using large-eddy simulations (LES) with very fine grids in the vicinity of the wall in order to resolve the near-wall structures. Since only a well-resolved LES ensures reliable results and hence allows a detailed analysis of turbulence, the Reynolds number investigated was restricted to Rec= 105 based on the chord length c. Admittedly, under real flight conditions Re c is considerably higher (about (35-40)' 106). However, in combination with the inclination angle of attack α=18 deg this Re c value guarantees a practically relevant flow behavior, i.e., the flow exhibits a trailing-edge separation including some interesting flow phenomena such as a thin separation bubble, transition, separation of the turbulent boundary layer, and large-scale vortical structures in the wake. Due to the fine grid resolution applied, the aforementioned flow features are predicted in detail. Thus, reliable results are obtained which form the basis for advanced turbulence analysis. In order to provide a deeper insight into the nature of turbulence, the flow was analyzed using the invariant theory of turbulence by Lumley and Newman (J. Fluid Mech., 82, 161-178, 1977). Therefore, the anisotropy of various portions of the flow was extracted and displayed in the invariant map. This allowed us to examine the state of turbulence in distinct regions and provided an improved illustration of what happens in the turbulent flow. Thus, turbulence itself and the way in which it develops were extensively investigated, leading to an improved understanding of the physical mechanisms involved, not restricted to a standard test case such as channel flow but for a realistic, practically relevant flow problem at a moderate Reynolds number. Copyright © 2006 by ASME.
Organization Units (connected with the publication): Universität Erlangen-Nürnberg
ISSN: 00982202
Publisher DOI: 10.1115/1.2175162
Appears in Collections:6 - Bibliographic Data - Publications of the HSU Researchers (before HSU)

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