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Old   August 13, 2009, 09:33
Default subsonic Airfoil Flow
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Hi to everyone,

I am studying on the flow around an airfoil at U=43 m/s and Reynolds=3E6.

I executed sonicFOAM NACA Airfoil tutorial for an example.

After I have read the User Guide, I understand that simpleFOAM can be used on steady-state laminar or turbulent problems. I activated the turbulence term and RANS model k-epsilon. The modified simpleFOAM files according to this problem are attached to this threat.

The problem is that the U, p contours are fully wrong as well as the coefficients of lift and drag.

I would like to hear some advices.

Regards,
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File Type: zip simpleFOAM.zip (4.9 KB, 91 views)
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Old   September 8, 2009, 09:45
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hmm 85 views and no reply

Can anybody post an airfoil/wing subsonic flow tutorial with the FOAM files?

I think this may help many openFOAM beginners.
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Old   September 10, 2009, 04:21
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Hmmm why can't i take any reply or comments?
Is it an hard question?
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Old   September 10, 2009, 15:14
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Matvej Kraposhin
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Can you post plots?
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Old   September 14, 2009, 07:21
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Hi,

is your solution converged? How many iterations did you run? Are your Cd and Cl values still changing?

I also have problems to get the right forces. But my cp plot looks quite ok.

Alex
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Old   September 15, 2009, 07:31
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Hi,

My solution never converges; Cd and Cl values change in a wide range interval.

I use "libforces.so" in order to print Cd, Cl and Cm. So I hope it is enough to give only directions to calculate the forces correctly.

Can you please upload your FOAM files Walex? If you don't prefer uploading, could you please write about your solver, BCs and mesh details.

Although flow around an airfoil at low AoAs is a basic problem on CFD topics, I am very suprised to see how hard it is with openFOAM.
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Old   September 15, 2009, 08:47
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Hi,

you have to give the direction for Cd and Cl and also your refence area and your reference length and additionally the density. You also have to name the patch the forces shall be calculated for.

What kind of solver do you use? I will have a look if I can upload something later. Quite busy in the moment...

Alex
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Old   September 17, 2009, 09:08
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Hi,

I agree with you about the reference values, directions and patch names. They are all ok.

I use parameters below:
simpleFOAM solver,
Newtonian transport model,
Realizable k-epsilon turbulence model,
Gridgen C-Mesh grid with yplus~1 sensitivity.

If you may find a chance to upload your simulation, it will be a good starting reference study for FOAM beginners like me.
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Old   September 17, 2009, 11:33
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Hi,

I am checking the seetings from the airfoil2D tutorial right now and they deliver good results for my pressure forces and therefore also for my lift result. But the viscous forces blow up after a while. I am testing some other settings... But here are my current settings. Maybe they can help you.
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File Type: zip myairfoil2D.zip (15.4 KB, 170 views)
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Old   August 8, 2011, 10:09
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After so many months, thank you walex.
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Old   March 3, 2013, 18:17
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hi

i am new here i didnt know about this solver and then the terms having the problem with the definition of the 0 folder because I don't know the exact meaning of the properties
alphat
mut
k
epilson
p
t and u

can any one help to know this solver

with regards
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