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B. Scheichl, A. Kluwick:
"Level of Turbulence Intensity Associated with Bluff-Body Separation for Large Values of the Reynolds Number";
Vortrag: 5th AIAA Theoretical Fluid Mechanics Conference, Doubletree Hotel Seattle Airport, Seattle, WA, USA; 23.06.2008 - 26.06.2008; in: "2008 AIAA Meeting Papers on Disc", American Institute of Aeronautics and Astronautics (AIAA), 7, TFM-8: Turbulent Boundary Layers II (2008), ISBN: 978-1-60086-995-2; Paper-Nr. AIAA 2008-4348, 23 S.

The paper deals with a rational and physically feasible description of gross separation from the surface of a plane and more-or-less bluff obstacle in an incompressible and otherwise perfectly uniform stream for arbitrarily large values of the globally formed Reynolds number. The analysis is initialized by a remarkable conclusion drawn from recent theoretical results that is corroborated by experimental findings but apparently contrasts common reasoning: the attached boundary layer extending from the front stagnation point to the position of separation at the body surface never attains a fully developed turbulent state, even in the limit of infinite Reynolds number. As a consequence, the boundary layer exhibits a certain level of turbulence intensity that is determined by the separation process governed by locally strong viscous/inviscid flow interaction. This mechanism is expected to be associated with rapid transition of the separating shear layer towards a fully developed turbulent state. Here a rigorous asymptotic analysis, essentially carried out without resorting to a specific turbulent closure and supported by a numerical investigation, of the topology of the boundary layer flow close to separation is presented.

bluff-body separation, boundary layers, Kirchhoff flow, matched asymptotic expansions, turbulence intensity

http://dx.doi.org/10.2514/6.2008-4348

http://publik.tuwien.ac.at/files/PubDat_164946.pdf