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Old   August 9, 2013, 15:42
Default Cl and Cd values very high
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Philip Brown
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Hi there.

I have managed to run my aerofoil simulation but I am getting very high values of Cd and Cl. I anticipated that there may be a bit of a problem with no modelling as a compressible flow (I used the SimpleFoam solver) but not to this extent!

I have attached the my project folder if anyone can help.

Thanks
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Old   August 10, 2013, 14:53
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Hi
send necessary files to me so that see if can do something:
force.of.love@gmail.com
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Old   August 10, 2013, 15:04
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Thanks immortality. Which filed would you need? I would guess posy processing, controldic and the whole of the 0 folder?
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Old   August 10, 2013, 15:09
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Hi
0 folder constant and system if you want me run it otherwise whatever you know may the problem be there.
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Old   August 10, 2013, 16:03
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why you have set rhoInf 1000? is the environment water?
but you have:
transportModel Newtonian;

rho rho [ 1 -3 0 0 0 0 0 ] 0.42;

nu nu [ 0 2 -1 0 0 0 0 ] 1.47e-05;
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Old   August 10, 2013, 16:06
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The environment is air at approx 11km. I have been trying to build this up from tutorials without knowing everything behind it and must have missed that. Would my rhoInf be 0.42 too or is there an equation that determines another value for it?
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Old   August 10, 2013, 16:12
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yes it would be .42
correct it a look at other files carefully.run it and I have a look if another problem occurred.
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Old   August 10, 2013, 16:16
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>.< silly me.. of course all the values ...inf are freestream aren't they. No wonder my values were so high as only the area what a true representation. So it takes the forcecoeffs actually pulls out a lift,drag, moment values and then divides them by 1/2 rho v^2 s. I think I see where I was going wrong. Thank you very much.
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Old   August 10, 2013, 16:17
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Values are now in the 0.02 area for drag which seems a lot better!
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Old   August 11, 2013, 02:41
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then it has been resolved?
I'm glad.what about Cl?
Send me your new settings.I want to have a look into it.
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Old   June 30, 2015, 04:01
Default Very high Cl
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P { margin-bottom: 0.08in; } Hi,
I was working on OpenFoam 2.3.1. Simulated some turbulence model with komega sst for flow past Circular Cylinder Re=100000, Cd=1.12, but always getting very high cl, rms =1.
Please suggest, if there is any trick.
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Old   June 30, 2015, 05:38
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is your grid fine enough near the wall of the cylinder to include viscous layer?
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Old   June 30, 2015, 06:02
Default Very high Cl
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I am using wallfunction, finess is such that, yplus value varying from 18 to 310, with average 172.
Attached Files
File Type: gz Cylinder_Re100000.tar.gz (128 Bytes, 0 views)
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Old   June 30, 2015, 06:06
Default High Cl value
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please help, I have attached my case above.
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