Figure 1. flow over a hump: Embedded LES using PANS

Q value

Q value colored by vorticity magnitude.



Researcher: Lars Davidson
lada@chalmers.se
Publications: [1-5]


Embedded LES
Embedded LES is an approach that combines LES and RANS, in which an LES region is embedded in any desired region, coupled with surrounding RANS simulations, and the location of the RANS-LES interaction is specified, for example, over a surface normal to the streamwise direction, as shown in Fig. 2. Regions with flow separation and vortex motions are typically treated using embedded LES, while the rest of the computational domain is accommodated by RANS. Q value

Figure 2. Channel flow: Embedded LES

In general, the LES region may be embedded in between upstream and downstream RANS regions. The emphasis in the present study is however on the RANS-LES coupling over the interface when going from an upstream RANS region to a downstream LES region as illustrated in Fig. 2. In this type of configuration, the critical issue in the RANS-LES coupling is how to create resolved turbulence at the interface and how to dampen modelled RANS turbulence when the flow enters into the LES region.

In [1-2], synthetic turbulent fluctuations are used for inlet boundary conditions. This is a first step for embedded LES. The method is applied for the flow over a 3D hill, the ONERA bump and the flow in an asymmetric diffuser. In [3,4] the PANS model is used in embedded LES for channel flow and the flow over a hump.
 


 

 
REFERENCES
  1. L. Davidson
    Inlet Boundary Conditions for Embedded LES, First CEAS European Air and Space Conference, 10-13 September, Berlin, Germany, 2007.
    View PDF file
     
  2. L. Davidson
    HYBRID LES-RANS: Inlet Boundary Conditions for Flows Including Recirculation, 5th International Symposium on Turbulence and Shear Flow Phenomena, Vol. 2, pp. 689-694, 27-29 August, Munich, Germany, 2007.
    (corrected)
    View PDF file
     
  3. L. Davidson and S.-H. Peng
    "Embedded LES Using PANS", I6th AIAA Theoretical Fluid Mechanics Conference, AIAA paper 2011-3108 27 - 30 Jun 2011, Honolulu, Hawaii.
    View PDF file
     
  4. L. Davidson and S.-H. Peng
    "Embedded Large-Eddy Simulation Using the Partially Averaged Navier-Stokes Model", AIAA J, DOI, 2013
     


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