Periodicity for 2D Airfoil
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Hi All,
I want to give periodicity in this airfoil. But when i select two vertices it give me meaage: "The periodic trnasformation has not been set in th tetin file cannot make nodes 13 and 11 periodic" What does it mean , i did basically translate one boundary on yaxis. Now want to make it periodic. Kindly help me out. Best Regards, 
you should first define periodicity in global mesh setup panel, then you can make the vertices periodic when editing the blocks. Have a try!

Dear zeitistgeld,
In 2D what does it mean "Blocking"? Where are the 4 vertices? In 2D I have two edges which are in opposite sides and I want to make them periodic. For instance I want to make a periodic TOP and BOTTOM edges in my 2D rectangular CAD model and they have just 2 vertices not 4 and when I try to define the same vertices twice it complains about node indices or something like this. I don't understand the logic. Could you please let me know how can define a block for 2D case? Regards, Siroos 
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If you have a rectangle, then you make block with the option "2d planar" and get 4 vertices (2 pairs of vertices).
http://www.cfdonline.com/Forums/att...1&d=1318319894 In the global mesh setup, set the geometry as translational periodic in the y direction as you want (see below) http://www.cfdonline.com/Forums/att...1&d=1318320066 In the edit block panel, set the periodic pairs of vertices, totally you have to make 2 pairs of vertices since it is 2 dimensional.(1 1 1>1 2 1, 2 1 1>2 2 1) http://www.cfdonline.com/Forums/att...1&d=1318320098 http://www.cfdonline.com/Forums/att...1&d=1318320130 
Thanks for your quick reply. I am going to do your comments.

As I work in ICEM CFD 13, I didn't get your red arrows to show the periodicity in y direction. In "Global Mesh Parameters=>Priodicity=>Translational" there is a "offset" parameter that I think shows the direction of the periodicity. I don't know what does really mean?
I checked the mesh quality for periodicity in TOP and BOTTOM edges and it says that "Running diagnostics for Periodic problems in subset "all" no problems found" is it ok? 
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The problem is still there. I Think it is a little bit different with ANSYS 12. Editing the vertices made me angry. Maybe there is a trick that I don't figure out. I attached stepbystep what I did.
I don't know how should specify that 2points (in two opposite edges) are periodic because it didn't ask anything about the input order of the points and just ask 4vertices all the time. Let say for instance 0,1,2,3 are my input vertices (corners of my rectangle). How Ansys knows which one is periodic with 0? Attachment 9513 Attachment 9514 Attachment 9515 Attachment 9516 
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Hi,
I think I got your procedure now, the only problem is when I define 2 pairs of verticed and then I push the "Apply" button, I get this message: "No 2 vertices selected". and when I want to select the vertices again it complains about: "nodes are already periodic twins of each other". Any comments? Attachment 9518 Attachment 9519 
I think you have made the vertices periodic since the message popped up saying "already periodic twins". To check out, right click vertex on the left hand dirctory tree and tick up "show periodic", something like that, you will see the red arrows indicating periodic pairs of vertices. Good luck!

Many thanks for your patient and help.
You are right. now I can see the arrows. 
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