# zero boundary condition on the axis.

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 July 6, 2010, 16:06 zero boundary condition on the axis. #1 New Member   yu Join Date: Nov 2009 Posts: 26 Rep Power: 9 Sponsored Links Hi, I want to use Openfoam to model a cylindrical problem. I am using a 5 degree pie shape mesh with two wedge on the front and back and one symmetryPlane at the Axis. I have a vector field A, My question is how can i define boundary condition on the Axis as zero? Thanks, Yu

July 7, 2010, 02:20
#2
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Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
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Quote:
 Originally Posted by universez I have a vector field A, My question is how can i define boundary condition on the Axis as zero?
On the (symmetry?) axis you don't have any boundary conditions because there is no patch you can impose some.

As a matter of fact there will be a zeroGradient on the axis as this is a symmetry axis.
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 July 7, 2010, 03:47 #3 New Member   Join Date: May 2010 Location: Cologne Posts: 27 Rep Power: 9 so you can write for each boundary condition: Axis //name of the axis-patch { type symmetryPlane; } _____ I don't kow if it is possible to make the Cylinder with a "bore hole" through the middle axis and then define the resulting tiny patch as zero if this is really necessary for your case...

 July 13, 2010, 15:47 question to wedge-type #4 New Member   Join Date: Jul 2010 Posts: 10 Rep Power: 9 hello, i also have a question to wedge-type.. why it is possible to have exactly 5 degree for wedge-type? Are there more inaccuracies in the solutions when using more degrees? thanks a lot.. noramat Last edited by noramat; July 13, 2010 at 16:15. Reason: another question

July 14, 2010, 06:16
#5
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Hello (one more time )...
Quote:
 Originally Posted by noramat why it is possible to have exactly 5 degree for wedge-type? Are there more inaccuracies in the solutions when using more degrees?
Similar questions have already been posted here and replied by hrvoje. On that page there are also some more hints on creating a wedge.
enjoy!

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