lesfoil

LESFOIL
Large Eddy Simulation of Flow Around Airfoils
A Brite-Euram Project



Coordinator: Lars Davidson
lada@chalmers.se
Researcher at Chalmers: Simon Dahlström
lada@chalmers.se
Start of project: February 1997
End of project: January 2001


SUMMARY
Computational Fluid Dynamics is an important tool when designing aircraft. For conventional aircraft under cruise conditions, the current generation of CFD (Computational Fluid Dynamics) codes allows a computer-based design to be achieved with some confidence. The design process of future aircrafts requires extensive research and development in CFD. Efficient and accurate CFD methods allow the aircraft industry to reduce the extensive experimental testing which usually is very expensive. CFD will also allow faster development of new aircraft and modification of existing aircrafts, as it may be sufficient to use measurements only in the later stage of development.
 
To perform accurate numerical simulations of such complex flows, new and more advanced turbulence models are needed. It is expected that, at the end of the LESFOIL project, the feasibility of the application of Large Eddy Simulations (LES) to aerodynamic flows will have been assessed, both under the aspect of the reliability of results and of the computer resources needed for the calculations.
 
Given the starting position of the partners the existing experience and knowledge of LES, it is expected that very rapid progress can be achieved on the performance of an initial LES of flow around a simple airfoil. A considerable part of the supported time will be spent in carefully analyzing results of such a simulation in order to optimize the numerical methods, investigate the size and refinement of the mesh required for a useful LES to be carried out for airfoils, near-wall treatment, transition, and investigating alternative subgrid models. The main objectives of the project are:
  • To provide know-how of an advance CFD method to the European aeronautical industry.
  • when will LES be feasible for the European aeronautical industry?
  • Demonstration of the feasibility of LES of flow over an airfoil.
  • Assessment of the computational requirements to carrying out LES for the simple airfoil and for more complex configurations in future.
  • Development of highly efficient numerical methods for the LES of airfoil flows.
  • Comparisons of competing (dynamic) subgrid-scale models for these flows.
The work is divided into four Tasks.
  • Development of subgrid models. If reliable subgrid models are developed, a larger portion of the turbulence could be modelled, allowing coarser grids.
  • Development of efficient numerical parallel methods. LES is computationally very expensive, and thus it is extremely important to reduce the computation time as much as possible.
  • Near-wall treatment. At high Reynolds numbers, LES requires a fine grid in all three coordinate directions. Use of wall functions or simple RANS (Reynolds Averaging Navier-Stokes) turbulence models in the near-wall region will be studied. This would allow us to use coarser grid spacing, especially in the streamwise and spanwise directions.
  • LES of airfoil flow.

 
PARTNERS
 
 Chalmers, Sweden, Coordinator
L. Davidson lada@chalmers.se
 
Alenia, Italy
N. Ceresola cfd@liat.alenia.polito.it
 
CERFACS, France
F. Ducros ducros@cerfacs.fr
 
Dassault, France
M. Mallet michel.mallet@dassault-aviation.fr
 
Fluent Europe Ltd, UK
D. Cokljat davor@fluent.co.uk
 
Karlruhe University, Germany
W. Rodi rodi@ifh.bau-verm.uni-karlsruhe.de
 
ONERA, France
T.H. Le thle@onera.fr
 
University of Surrey, UK
P. Voke p.voke@surrey.ac.uk
 
Queen Mary & Westfield College, UK
M. Leschziner Mike.Leschziner@qmw.ac.uk
 
Results from the Midterm Report are summarized in:
L. Davidson, "LESFOIL: A European Project on Large Eddy Simulations Around a High-lift Airfoil at High Reynolds Number", ECCOMAS 2000, European Congress on Computational Methods in Applied Sciences and Engineering, 11-14 September, Barcelona, Spain, 2000
View PDF file
 
The final report is available as:
L. Davidson, D. Cokljat, J. Fröhlich, M.A. Leschziner, C. Mellen and W. Rodi (eds.), "LESFOIL: Large Eddy Simulation of Flow Around a High Lift Airfoil", Notes on Numerical Fluid Mechanics, Vol. 83, Springer Verlag, 2003.

Get the book at Springer in Europe or U.S.


REFERENCES (CHALMERS' WORK)
  1. S. DAHLSTRÖM and L. DAVIDSON
    "Large Eddy Simulation of the Flow Around an Airfoil", AIAA paper 2001--0425, Reno, NV, 2001.
    View PDF file
     
  2. S. DAHLSTRÖM and L. DAVIDSON
    "Large Eddy Simulation of the Flow Around an Aerospatiale A-aerofoil", ECCOMAS 2000, European Congress on Computational Methods in Applied Sciences and Engineering, 11-14 September", Barcelona, Spain, 2000.
    View PDF file
     
  3. S. DAHLSTRÖM and L. DAVIDSON
    "Large Eddy Simulation Applied to a High-{R}eynolds Flow Around an Airfoil Close to Stall", AIAA paper 2003--0776, Reno, NV, 2003.
    View PDF file
     

 

 


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