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Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

Cheng, W. and Pullin, D. I. and Samtaney, R. (2015) Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer. Journal of Fluid Mechanics, 785 . pp. 78-108. ISSN 0022-1120.

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We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the time- and space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number Re_θ based on the momentum boundary-layer thickness θ. Comparison with data from the first case at Re_θ=2000 demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, Re_θ, the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger Re_θ=11000 of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.

Item Type:Article
Related URLs:
URLURL TypeDescription
Cheng, W.0000-0003-3960-4162
Samtaney, R.0000-0002-4702-6473
Additional Information:© 2015 Cambridge University Press. Received 16 March 2015; revised 19 August 2015; accepted 15 October 2015; first published online 11 November 2015. W.C. and R.S. were supported by the KAUST Office of Competitive Research Funds (OCRF) under Award No. URF/1/1394-01. D.I.P. was partially supported under KAUST OCRF Award No. URF/1/1394-01 and partially by NSF award CBET 1235605.
Funding AgencyGrant Number
King Abdullah University of Science and Technology (KAUST)URF/1/1394-01
Subject Keywords:turbulence modelling; turbulent boundary layers; turbulent flows
Record Number:CaltechAUTHORS:20160105-124250245
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63384
Deposited By: Tony Diaz
Deposited On:05 Jan 2016 20:48
Last Modified:03 Oct 2019 09:27

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