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Exploring a Method for Improving Turbulent Separated-Flow Predictions with kappa-omega ModelsA particular failing of Reynolds-averaged Navier-Stokes separated turbulent flow computations is addressed within the context of a kappa-omega two-equation turbulence model. The failing is the tendency for turbulence models to under-predict turbulent shear stress in the shear layers of some separation bubbles, yielding late boundary layer reattachment and recovery. Inspired by unpublished work of Volker, Langtry, and Menter, the author undertook an independent investigation in an attempt to improve the ability of the Menter shear stress transport (SST) model to predict flowfield characteristics in and downstream of separation bubbles. The fix is an ad hoc term that is a function of the local ratio of turbulent production to dissipation; it is used to multiply the omega-destruction term, increasing eddy viscosity in separated regions. With this fix, several flowfields are investigated. Results show that, although the "separation fix" can provide dramatic improvement in some cases, it is not consistently good for all flows. Thus, although it may prove helpful in many situations in its current form, this model may benefit from further refinements, including better sensitization to the energetics of turbulence in the separated region.
Document ID
20090042511
Acquisition Source
Langley Research Center
Document Type
Technical Memorandum (TM)
Authors
Rumsey, Christopher L. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 24, 2013
Publication Date
December 1, 2009
Subject Category
Aerodynamics
Report/Patent Number
L-19779
NASA/TM-2009-215952
LF99-9618
Funding Number(s)
WBS: WBS 561581.02.08.07.20.15
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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