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-   -   Creating named selection for a line sketch (http://www.cfd-online.com/Forums/ansys/105426-creating-named-selection-line-sketch.html)

amir00251 July 30, 2012 21:14

Creating named selection for a line sketch
 
I am trying to model a simple rotating hallow cylinder, image below. I need to create a named selection for the central axis to be able to define rotation of axis when I am defining the rotational speed.

The problem is, I cannot create a named selection for the rotational axis in Geometry. I have sketched a line but you cannot create a named selection from a line.

I am new to Ansys, so would appreciate a help on this.

http://www.mediafire.com/conv/1d9509...9cd78f626g.jpg

flotus1 July 31, 2012 04:22

1 Attachment(s)
Activate the selection of lines first.

amir00251 July 31, 2012 05:38

Hello, thanks for your reply. I still cannot select the center line to create a Named Selection after choosing line in selection type.

I can create Named selections for the surfaces of the body or for whole body but not for that center line. That center line is just a sketch... this should give a clue?

I read in another forum that if you want to create a Named Selection for a closed area inside a surface, you should extrude and change the option from add material to imprint ... something like this is required but I can not extrude a single line??

flotus1 July 31, 2012 05:49

I see...
You need the line only to define the axis of rotation? In your picture, the line coincides with an axis of the global coordinate system.
It should be possible to select this axis as the axis of rotation.

amir00251 July 31, 2012 06:07

Yes, I was thinkng that I can easily choose z axis as axis of rotation, but again there is not that possibility when I am defining rotatinal velocity ... would you please give details if this is possible.

flotus1 July 31, 2012 06:42

1 Attachment(s)
Actually it is not possible to choose the axis directly.
Instead, choose "define by" -> "components".
Now you can apply any rotation you like.
If you are not simulating structural mechanics, well sorry for assuming that.

amir00251 July 31, 2012 08:02

Thanks alot for your help, it did solve the problem. I think instead of Named Selection, I should look at how to define a vector...
or use component as you pointed out above...


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