- Towards Wall Models for LES of Separated Flows

# Towards Wall Models for LES of Separated Flows

Publication date

2007

Document type

Conference paper

Author

Organisational unit

Conference

ITI Conference on Turbulence 2005, Sept. 25–28, 2005, Bad Zwischenahn, Germany

Book title

Progress in Turbulence II

First page

267

Last page

270

Peer-reviewed

✅

Part of the university bibliography

Nein

Abstract

A key technology for the application of LES to high–Re flows of engineer-

ing interest is an appropriate wall modeling strategy bridging the near–wall

region and thus avoiding the expensive DNS–like resolution. Standard wall

models such as Schumann’s model [1] work well for attached flows, e.g. plane

channel flow, where the averaged quantities required can be calculated. The

model reads: τ w = [ |τ w | / |v tan| ] v tan. Hence, a phase coincidence of the

instantaneous wall shear stress τ w and the tangential velocity v tan at the

wall–nearest grid point is assumed. More complex 3–D flows with large pres-

sure gradients or local separation are not well reproduced. For such flows the

mean values required are not accessible and the validity of the law of the

wall used is questionable. The model of Werner and Wengle [2] (WW) reads

τ w = f (|vtan|) vtan where f (|vtan|) is expressed by a law of the wall applied

directly to the instantaneous quantities. Therefore, this model is also not able

to predict separated flows correctly. The main reason is the dependence of

τ w on additional quantities such as the pressure gradient ∇p. Thus, attempts

were made to take ∇p into account, e.g. by Hoffmann and Benocci [3].

ing interest is an appropriate wall modeling strategy bridging the near–wall

region and thus avoiding the expensive DNS–like resolution. Standard wall

models such as Schumann’s model [1] work well for attached flows, e.g. plane

channel flow, where the averaged quantities required can be calculated. The

model reads: τ w = [ |τ w | / |v tan| ] v tan. Hence, a phase coincidence of the

instantaneous wall shear stress τ w and the tangential velocity v tan at the

wall–nearest grid point is assumed. More complex 3–D flows with large pres-

sure gradients or local separation are not well reproduced. For such flows the

mean values required are not accessible and the validity of the law of the

wall used is questionable. The model of Werner and Wengle [2] (WW) reads

τ w = f (|vtan|) vtan where f (|vtan|) is expressed by a law of the wall applied

directly to the instantaneous quantities. Therefore, this model is also not able

to predict separated flows correctly. The main reason is the dependence of

τ w on additional quantities such as the pressure gradient ∇p. Thus, attempts

were made to take ∇p into account, e.g. by Hoffmann and Benocci [3].

Cite as

Breuer, M., Kniazev, B., Abel, M.: Towards Wall Models for LES of Separated Flows, ITI Conference on Turbulence 2005, Sept. 25–28, 2005, Bad Zwischenahn, Germany, In: Progress in Turbulence II, eds. Oberlack, Khujadze, Günther, Weller, Frewer, Peinke and Barth, Springer Proceedings in Physics, vol. 109, ISBN 978–3–540–32602–1, pp. 267–270, Springer Verlag, Berlin Heidelberg New York, (2007).

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