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CD and CL values are way off, even though I've used inflation layers

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Old   July 30, 2013, 11:20
Default CD and CL values are way off, even though I've used inflation layers
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Bart A.
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I have a flow simulation where at low angles of attack (~10deg) the CL and CD values are very far from the reference data.
Simulation summary:

- Sharp edged flat plate like structure.
- Inflation layer on flat plate
- Standard k-epsilon model

At higher angle of attack (~40deg) the CL and CD values show resemble the reference data acceptably.
The error of low AoA CL and CD is not really dependent on the mesh. The error is there with 3 million cells, but also with 6 million cells.

I have applied inflation layers, refined the mesh and refined the timestep to no avail. What else can I do to get acceptable results?
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Old   July 30, 2013, 13:09
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There is a section in the FAQ that covers most of the factors influencing the result of a cfd analysis.

http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F
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Old   July 31, 2013, 03:23
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Change the turbulence model from k-epsilon to SST and make sure the mesh has a y+ = 1.
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Old   August 5, 2013, 16:11
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@siw:

Thank you for the suggestion. I tried this out (calculated the first inflation layer thickness based on y+ with the CFD-Online calculator) but the CL and CD values only differ around 1% from the k-epsilon model with an y+ of 30.

This means that the coefficient values are still far from my wind tunnel reference data.
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