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Old   May 18, 2014, 02:54
Default unable to simulate an airplane wing
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Hedley
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I have lost the plot - run su2 on airplane wing which has 1.6meter chord - 800mm tip and 3 meter half span . Set .cfg file for +- 75 KTS and have tried many diff parameters and solution methods . The outputs just don't make sense . Attached find CL and CD for a 7 degree AOA ????

any assistance in where I have gone wrong . i have attached .cfg settings
Attached Images
File Type: jpg clandcd.JPG (38.3 KB, 16 views)
File Type: jpg seven degrees.JPG (39.8 KB, 21 views)
File Type: jpg settings1.jpg (102.4 KB, 14 views)
File Type: jpg settings2.jpg (84.5 KB, 15 views)

Last edited by hedley; May 18, 2014 at 03:30. Reason: forgot attachments
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Old   May 18, 2014, 21:19
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Francisco Palacios
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Quote:
Originally Posted by hedley View Post
I have lost the plot - run su2 on airplane wing which has 1.6meter chord - 800mm tip and 3 meter half span . Set .cfg file for +- 75 KTS and have tried many diff parameters and solution methods . The outputs just don't make sense . Attached find CL and CD for a 7 degree AOA ????

any assistance in where I have gone wrong . i have attached .cfg settings

I think it could be related with the non-dimensionalization... there is something strange... SU2 says that the z projection is ~6000m2? Could you please double check that the grid is in meters? On the other hand, it would be great if you run the code dimensionally

% Reference pressure (1.0 N/m^2 by default, only for compressible flows)
REF_PRESSURE= 1.0
%
% Reference temperature (1.0 K by default, only for compressible flows)
REF_TEMPERATURE= 1.0
%
% Reference density (1.0 Kg/m^3 by default, only for compressible flows)
REF_DENSITY= 1.0

Best,
Francisco
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Old   May 19, 2014, 14:58
Default Wing analysis problems
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Hedley
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The grid was done in pointwise in inches so I have scaled to meters and also as suggested set all values to 1 to get a dimensioned result. The solver still has Cl and cd increasing on each iteration ? . Using AVL from Drela I get some idea of what I should expect but SU2 seems to be way out on these . I'm sure it is a setting or .... Many
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Old   June 5, 2014, 15:29
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David Manosalvas
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Hedley,

Is your simulation converged? If you are running RANS, are you using a mesh with the right y+ and at least 20 elements in the boundary layer? Some times when running viscous problems you need to tweak some of the parameters such as the CFL number to improve your convergence rate, but in any case you will need to run this simulation for a few thousand iterations before you can see any meaningful results.

Hope this helps,

David
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