Dear CFD-friends,

I'm trying to find experimental data for separated transonic flow past an aerofoil or a wing section. The case will be used for LES. Specification as follows:

1) Mach_freestream around 0.5-0.9. 2) Re based on chord and freestream values less than 1.E6. 3) Flow separation 4) Detailed experimental data available. With detailed data I mean velocity profiles, boundary layer height, correlations of fluctuations and so on (data other than Cp distributions)

If a case like this exists please give me the reference.

What I found so far: 1) The ERCOFTAC database contain only incompressible attached flows 2) AGARDH-report AR-303 (1994). The cases are either at low Mach number or at high Reynolds number and no detailed data are available. 3) Numerical simulation of compressible Navier- Stokes flows: a GAMM-workshop (1987). The workshop considered laminar flows to "avoid introduction of turbulence models and large instabilities due to strong shock-boundary layer interaction".

Thinking about running some transonic wind tunnel testing on your own? Transonic separated flow over a wing is likely to be un-steady and with shock waves.

Dear Mr Chien,

thanks for your reply. No I'm not thinking about running any transonic wind tunnel testing of my own and the flow should be un-steady and with shock waves. I want to do Large Eddy Simulations of this type of case if detailed experimental data are available. The Re limit (Re less than 1.E6) is due to resolution requirements. Running coarse grid LES put great demands on the SGS-model. The flow probably separates and a laminar bubble may be formed downstream the shock. Transition may start inside the laminar separated bubble. The instabilities may grow to form a turbulent boundary layer further downstream. Only the dynamic formulation is expected to perform satisfactorily in this variety of flow situations. We have developed a dynamic SGS-model admitting anisotropi in the SGS-terms. In our formulation it is the divergence of the SGS stress tensor which is modelled rather than the SGS stress tensor itself. Using three model parameters, each of them are expressed direct and independently. The model applied to flow around wing sections have been presented in AIAA-paper 97-1931 "Large Eddy Simulation of Compressible Flow Around a NACA 0012 Wing Section" and AIAA-paper 98-0405 "Large Eddy SImulation of Separated Transonic Flow Around a Wing Section". I want to compare coarse grid LES with experimental data. In order to get one or more grid points inside the laminar sublayer I use a stretched grid (in the normal direction). I know this is a formidable task to simulate un-steady external flow around a complex geometry with shock waves present. However, we want to push the limit.

Looking forward to your (or anyone else) response.

Best regards,

J. Held

I have some literature about experimental data for transonic flow. For I'm studying unsteady flows, I usually refer to AGARD-R-702; you can also look at AGARD-AR-138, "Pressure distributions on the Onera M6 Wing at Transonic Mach Numbers" from Schmitt and Charpin, May 1979. I hope they will help you.

try: L.Fottner (ed.) AGARD AR 275 'Test Cases for Computation of internal flows in aero engine components',1990