Abstr:UFR 3-34: Difference between revisions
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RANS to LES in the separated shear layer resulting in a significant deviation of CFD predictions | RANS to LES in the separated shear layer resulting in a significant deviation of CFD predictions | ||
from experimental data. The flow past the 2D NASA Wall-Mounted Hump (2DWMH) studied | from experimental data. The flow past the 2D NASA Wall-Mounted Hump (2DWMH) studied | ||
in the experiments of Greenblatt ''et al''. [‌[[UFR_3-34_References#1|1]]] and by Naughton ''et al''.[‌[[UFR_3-34_References#2|2]]] possesses all the above | in the experiments of Greenblatt ''et al''. [‌[[UFR_3-34_References#1|1]]] and by Naughton ''et al''. [‌[[UFR_3-34_References#2|2]]] possesses all the above | ||
mentioned features, thus presenting, in terms of geometry, a relatively simple but nonetheless | mentioned features, thus presenting, in terms of geometry, a relatively simple but nonetheless | ||
quite representative Test Case (TC) for the considered UFR. The experiments had been designed | quite representative Test Case (TC) for the considered UFR. The experiments had been designed | ||
Revision as of 14:26, 30 November 2017
Smooth wall separation and reattachment at high Reynolds numbers
Abstract
Separation of a turbulent boundary layer from a smooth wall caused by Adverse Pressure
Gradient (APG) and subsequent reattachment of the separated shear layer and relaxation of the
reattached boundary layer are extremely complex phenomena encountered in numerous flows of
high interest for the aerospace industry, civil engineering, ground transportation etc. Its accurate
prediction presents a serious challenge for the RANS modelling as well as for the scale-resolving
approaches, such as LES and hybrid RANS-LES methods. For the latter, a major difficulty is
associated with so called “grey area issue”, which shows up as a strong delay of transition from
RANS to LES in the separated shear layer resulting in a significant deviation of CFD predictions
from experimental data. The flow past the 2D NASA Wall-Mounted Hump (2DWMH) studied
in the experiments of Greenblatt et al. [1] and by Naughton et al. [2] possesses all the above
mentioned features, thus presenting, in terms of geometry, a relatively simple but nonetheless
quite representative Test Case (TC) for the considered UFR. The experiments had been designed
for CFD validation, and their results were used for this purpose in numerous computational
studies including those carried out in the framework of specially organized international
workshops http://cfdval2004.larc.nasa.gov/cas3.html [3] and in the course of two EU projects,
ATAAC
http://cfd.mace.manchester.ac.uk/twiki/bin/view/ATAAC/WebHome
[4]
and
Go4Hybrid http://go4hybrid.mace.manchester.ac.uk/go4hybrid/bin/view/Main/WebHome [5].
The purpose of this document is to summarise results of the systematic numerical studies of the
2DWMH flow carried out within the Go4Hybrid project with the use of enhanced hybrid
methods in a comparison with similar results obtained by Uzun and Malik [6] who employed
Wall-Resolved LES of the flow on extremely large grids. Hence these results may serve as an
additional dataset for validation of less expensive approaches. This analysis combined with a
brief overview of RANS models performance for the 2DWMH test case presented at the NASA
Turbulence Modeling Resource Portal https://turbmodels.larc.nasa.gov/nasahump_val.html [7]
gives a clear idea on capabilities and restrictions of different turbulence modelling/simulation
strategies with regard to the considered UFR, in general, and the 2DWMH test case in particular
Contributed by: E. Guseva, M. Strelets — Peter the Great St. Petersburg Polytechnic University (SPbPU)
© copyright ERCOFTAC 2024