Detached Eddy Simulation for Industrial Aerodynamics |
Assist. prof.: |
Sinisa Krajnovic sinisa@chalmers.se |
Project leader: |
Lars Davidson lada@chalmers.se |
Cooperation: | All DESider partners |
Sponsors: | EU project |
Publications: | [1-10] |
Start of project: | January 2004 |
End of project: | July 2007 |
PROJECT Chalmers is workng on development of hybrid LES-RANS. A one-equation RANS model is used in the near-wall region and a LES model is used in the remaining part of the flow. The matching takes place in the inner region of the log-law region. As in imbedded LES, the interface condition between the URANS region and the LES region is crucial for the sucess of method. The resolved turbulence supplied by the URANS region to the LES region does not have any reasonable turbulent characteristics: the resolved turbulent time and length scales of the unsteady RANS flow are not representative of the real turbulence at all. A remedy is to at the interface superimpose fluctuations at the LES side of the interface. The turbulent fluctuations can be taken from a DNS of a generic boundary layer, from synthetic turbulence (the turbulence is generated in wavenumber space) or from a vortex model. As an alternative, a hybrid model based on the k-omega model has been developed. K and omega are solved everywhere, but in the LES region the modelled length scale is taken from the filter width. The locations of matching points between the LES and the URANS region are defined from physical quantities allowing the matching points to be defined locally in space and time. This makes the method attractive for complex geometries. Chalmers is working on four test cases: channel flow, the Ahmed body, the 3D hill and a short cylinder mounted on a wall. REFERENCES
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