error problems between experimental and numerical study
 

Hello,

i am a spanish man that are doing an aerodynamic study of a motorsport spoiler. I had done a numerical simulation with star ccm+ and now i am taking some information with this spoilers in a wind tunnel. My project tutor/teacher said me that the cfd can be until 20% of error (more or less) between the cfd mesurements and the mesures of wind tunnel. I don't understand because my mesurements in wind tunnel are ok with Drag component but not with Lift component (Downforce).

For example: with 0 degrees inclination the cfd study shows 38,33 N of Downforce and 8,84 N of Drag and the wind tunnel measures are 22,5 N of Downforce and 7,1 N of Drag. If I applicate the teacher's theorem, the drag are in the 20% of error. 7,1 + (20% of 8,84 = 1,77) = 8,87 N but if I do the same with the Downforce the result is not valid with this theory.

Someone know if is true that's the maximum error between cfd and experimental study are 20% or can be more?? What can I do?

Thanks,

david.

Mesh problem, maybe wrong solver.

Can you post a picture of your mesh. As well as tell us your physic models? Then we can try and help!

Are you positive all the boundaries are set right??

Use fine mesh with quality.

Very helpful... maybe he can't :D:D:D:D