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Mesh of a NACA Airfoil

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Old   November 21, 2009, 09:13
Default Mesh of a NACA Airfoil
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Fred
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Hello,

I need to study the NACA 23012 airfoil. I found its coordinates and put them in Gambit.

I was wondering how to mesh it, as I need to find the flow around the wing at different angles of attack (I hope that I wont need to make 23 different mesh to find the flow for an angle of attack coming from -2 to 20...).

Is there an easy way to do so ?

An other point is that I'll have to take in account the sweep angle of the wing... How to simulate this as I will work in 2D ?

Thanks a lot,

Fred
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Old   November 21, 2009, 15:28
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Hi,
try to visit this link

http://hpce.iitm.ac.in/website/Manua...help/index.htm

There's some fluent example. Try to mesh the airfoil simply looking that! However depends on what are you looking for, and what type of flow are you studying.

If you want to study a different angle of attack, do only a .msh file, and then set in fluent a different velocity ( Vx = ... Vy = ...).

I think that it's impossible to simulate 3D effects working in 2D model... . The only way ( not so easy...) is to write a UDF that modify Velocity in order to take into account that effect!
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Old   November 22, 2009, 08:33
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Thanks for your answer.

The thing is that for a different angle of attack, the flow after the wing will be at a different position (higher or lower), so my mesh wont be fine enough where it should be.

By the way, what y+ should I consider for this study :

Flow around a NACA 23012 airfoil, subsonic (M 0.84).

Thx ^^
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Old   November 22, 2009, 09:33
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Hi,
honestly, I never calculate the flow around a wing through CFD. I only do that in theory at university. However, to calculate y+ try to see Fluent Manual. I remember there is a chapter that explain how to calculate y+ and so how to build the mesh around the airfoil!
However, remember to compare your result with experimental data ( or simply with Xfoil)!
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Old   November 22, 2009, 10:27
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Well, Your case is as same as mine. It's difficult to get Cd & Cl as same as your experiment. I think for simulating with that speed will need great Y plus. but if you do that you cannot get Cd close by experiment. because to get right Cd is needed inflated boundary. complicated enough
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Old   November 22, 2009, 10:29
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Here some useful discussion about y plus
Check this out.
www.cfd-online.com/Forums/fluent/50751-how-abtain-correct-y-plus-value.html
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Old   November 22, 2009, 17:00
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Hi

I strongly recommend gridgen for mesh generation. You can easily create a C-grid for 2d problems. Moreover you can take a look at the following link about fluent interface.

http://courses.cit.cornell.edu/fluent/airfoil/index.htm

The first y+ value will depend on the turbulence model. Take a look at the manual for detailed information about the models. The following link is also useful to calculate y+ value

http://geolab.larc.nasa.gov/APPS/YPlus/
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