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CD and CL values are way off, even though I've used inflation layers |
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July 30, 2013, 11:20 |
CD and CL values are way off, even though I've used inflation layers
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#1 |
Member
Bart A.
Join Date: Feb 2012
Posts: 45
Rep Power: 0 |
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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July 30, 2013, 13:09 |
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#2 |
Super Moderator
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,396
Rep Power: 46 |
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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July 31, 2013, 03:23 |
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#3 |
Senior Member
Stuart
Join Date: Jul 2009
Location: Portsmouth, England
Posts: 731
Rep Power: 25 |
Change the turbulence model from k-epsilon to SST and make sure the mesh has a y+ = 1.
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August 5, 2013, 16:11 |
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#4 |
Member
Bart A.
Join Date: Feb 2012
Posts: 45
Rep Power: 0 |
@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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