Armenio / Geurts / Fröhlich Direct and Large-Eddy Simulation VII

Proceedings of the Seventh International ERCOFTAC Workshop on Direct and Large-Eddy Simulation, held at the University of Trieste, September 8-10, 2008
1. Auflage 2010
ISBN: 978-90-481-3652-0
Verlag: Springer Netherland
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, Band 13, 646 Seiten, eBook

Reihe: Ercoftac Series

After Surrey in 1994, Grenoble in 1996, Cambridge in 1999, Enschede in 2001, Munich in 2003 and Poiters in 2005, the 7th Workshop, DLES7, will be held in Trieste, again under the auspices of ERCOFTAC. Following the spirit of the series, the goal of this latest workshop is to establish a state-of-the-art of DNS and LES techniques for the computation and modeling of transitional/turbulent flows covering a broad scope of topics such as aerodynamics, acoustics, combustion, multiphase flows, environment, geophysics and bio-medical applications. This gathering of specialists in the field should once again be a unique opportunity for discussions about the more recent advances in the prediction, understanding and control of turbulent flows in academic or industrial situations.

Zielgruppe

Research

Autoren/Hrsg.

Armenio, Vincenzo

Geurts, Bernard

Fröhlich, Jochen

Inhaltsverzeichnis

Fundamentals.- Methodologies and Modelling Techiques.- Les Modelling Errors.- Scalars.- Active Scalars.- Environmental and Multiphase Flows.- Aerodynamics and Wakes.- Compressible Flows.

Leseproben

"LES Meets FSI – Important Numerical and Modeling Aspects (p. 245-246)

M. Breuer1,2 and M. Münsch2

1 Dept. of Fluid Mechanics, Institute of Mechanics, Helmut-Schmidt-University Hamburg, Holstenhofweg 85, D-22043 Hamburg, Germany, [e-mail] 2 Institute of Fluid Mechanics, University of Erlangen-N¨urnberg, Cauerstr. 4, D-1058 Erlangen, Germany, [e-mail]

Abstract The paper is concerned with two main aspects, which should be considered when large–eddy simulation (LES) is married to ?uid–structure interaction (FSI). First, the in?uence of moving grids leading to temporally varying ?lter widths and thus additional commutation errors on the quality of the predicted results is thoroughly investigated. Second, a new partitioned coupling method based on the predictor–corrector scheme often used for LES is evaluated. A strongly coupled but nevertheless still explicit time–stepping algorithm results, which is very e?cient in the LES–FSI context. This new scheme is evaluated in detail based simulations around elastically supported cylindrical structures and a swiveling ?at plate.

1 Introduction

Fluid–structure interaction (FSI) plays a dominant role in many technical applications such as suspension bridges, o?-shore platforms or even vocal folds. Therefore, a strong need for appropriate numerical simulation tools exists for such coupled problems. In previous studies, FSI applications in the regime of laminar ?ows as well as turbulent ?ows using the RANS approach [5, 6] were numerically investigated. For that purpose, a partitioned fully implicit scheme was applied which coupled a three-dimensional ?nite-volume based multi-block ?ow solver for incompressible ?uids with a ?nite-element code for the structural problem.

This coupling scheme works e?ciently for large time step sizes typically used for implicit time-stepping schemes within RANS predictions. However, ?ow problems involving large-scale ?ow structures such as vortex shedding or instantaneous separation and reattachment are often not reliably predicted by RANS and more advanced techniques such as largeeddy simulation (LES) are required. To resolve the turbulent ?ow ?eld in time, LES uses small time steps.

Thus, in general explicit time-marching schemes are favored, especially predictor–corrector schemes [1,2]. Furthermore, for FSI applications the solution domain changes in time due to the displacement of the boundaries linked to the structure. Thus moving grids have to be used which has a direct in?uence on the ?ltering approach in LES. Thus the paper addresses the aspects of additional errors introduced (e.g., commutation errors) and code coupling, which should be considered when LES is married to FSI.

2 Important steps for joining LES and FSI

2.1 LES on moving grids

Within an FSI application the ?uid forces acting on the structure lead to the displacement or deformation of the structure. Thus the computational domain is no longer ?xed but changes in time. Besides other numerical techniques to account for these variations, the most popular one is the so-called Arbitrary Lagrangian–Eulerian (ALE) formulation. Here the conservation equations for mass, momentum (and energy) are re-formulated for a temporally varying domain."