Accuracy of results
 

Hello,

I'm trying to run a case in sonicFoam of a NACA 0012 airfoil, but I'm not being able to get accurate results, not even close to those expected regarding the CD. I tried to change some parameters, even the turbulence model, but I could not improve really much the results since I'm a recent new user of OpenFOAM. So I ask you what can I do to have more accurate results.

Here is the case:
/0
U
P
T
k
epsilon
mut
alphat

/system
controlDict
fvSchemes
fvSolution

The expected value for CD is around 0.008.

Thanks in advance,
J. Vieira

Dear Jefferson,

I believe there was a very good topic in this page where people discussed the same thing. However, in short, you can never predict drag coefficient with a high Reynolds turbulent models. In order to accurately predict the drag you have to accurately resolve the flow close to the airfoil which needs y+<1.
Nevertheless, I would like to know whether or not you were able to predict the lift coefficient in the stall region for that particular airfoil.

Hi miladrakhsha,

I appreciate your help. Since I've posted I improved a lot my results, the main problem was the quality of the mesh, the cells at the airfoil wall weren't thin enough and some discontinuities were causing numerical instabilities. At this moment I'm obtaining reasonably good results, but in my study I'm not watching the stall region, the interest relies on low angles of attack.

Best,
Jefferson Vieira