# Use UDF to change the attack angle of flow over 3D wing

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 May 3, 2013, 03:07 Use UDF to change the attack angle of flow over 3D wing #1 Member   Join Date: Jul 2009 Posts: 70 Rep Power: 10 Sponsored Links Hi everyone, I am a new with ANSYS FLUENT. I am doing simulation with the flow over 3Dwing (NACA0012). I want to change the attack angle by using UDF. Could anyone teach me how to use the UDF for this case? thanks you! Xavier

 May 3, 2013, 03:34 #2 Senior Member   Join Date: Aug 2011 Posts: 315 Rep Power: 14 Are you studying the pitching motion of the wing or you simply want to study the flow at several angles of attack?

 May 3, 2013, 05:55 #3 Senior Member   Ananthakrishnan.A.S Join Date: Feb 2012 Location: Mumbai (Bombay), India Posts: 157 Rep Power: 9 Hi, if it just the angle of attack which you want to change, you can do it directly by changing the x and y component of velocity in the velocity inlent boundary condition. If you want to learn to do it in udf you have to do the same by writing this component inside a small c program.. this is an example of how the inlet velocity is changed according to the y distance to get a profile http://combust.hit.edu.cn:8080/fluen...udf/node61.htm

 May 3, 2013, 14:42 #4 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,331 Blog Entries: 6 Rep Power: 45 You can also do it in workbench

May 15, 2013, 01:07
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Hi everyone,

Thanks to all of you!
@blackmask: I am not going to simulate for pitching motion, only do simulation for some AoA.
@Ananthakrishnan:
Because the wing is located in the virtual wind tunnel, is it ok when I change the AoA by change the Vx, Vy components?
Attached Images
 1.jpg (15.6 KB, 109 views) velocity.png (46.6 KB, 125 views)

 May 15, 2013, 05:22 #6 Senior Member   Ananthakrishnan.A.S Join Date: Feb 2012 Location: Mumbai (Bombay), India Posts: 157 Rep Power: 9 No, its not going to pose any serious threat..There will be some difference in magnitude of result between the two. But you will not be misguided..In brief, if there is a increase in lift then there will always be an increase whether you change the components of velocity or if you change the wing AOA. If you want a very very very precise result, later you can continue by changing the AOA. I suggest you to get an idea of whats happening by changing the components and then "if required" change the AOA

 May 15, 2013, 23:12 #7 Member   Join Date: Jul 2009 Posts: 70 Rep Power: 10 Thanks Ananthakrishnan, As I understand, for this case of fluid domain, the inlet bc is a straight line. This is different compare with the semi-circle (C-shape) as many people used. So I think that for every AoA we should change the geometry rather than change the velocity components. Because the top and the bottom are wall, they are not velocity inlet.

 June 14, 2013, 03:37 #8 New Member   bikalpa bomjan Join Date: Mar 2013 Posts: 5 Rep Power: 6 sir Ananthakrishnan i am doing a similar type of simulation but whet i set inlet velocity at certain angle of attack i get the flow accumulated at upper surface of wind tunnel giving uneven flow throughout the wind tunnel ( higher velocity at upper surface of wind tunnel and lower velocity at lower surface of wind tunnel) and i have chosen boundary conditions as symmetry for both upper and lower surface of wind tunnel

 June 26, 2016, 05:53 angle of attack in fluent #9 New Member   Join Date: Nov 2014 Posts: 1 Rep Power: 0 hi.i want to give angle of attack in fluent but i can not.please help me

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