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-   -   Axis boundary condition. (http://www.cfd-online.com/Forums/fluent/100437-axis-boundary-condition.html)

A7A April 25, 2012 11:12

Axis boundary condition.
 
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Hi,

When i try to make axis boundary condition to solve an axissymmetric problem Fluent gives me this warning:

Warning: non-positive volumes exist.

this is a picture of my mesh.

Thank you.

A7A April 25, 2012 12:40

Any solutions?:confused:

LuckyTran April 25, 2012 13:41

Quote:

Originally Posted by A7A (Post 356940)
Hi,

When i try to make axis boundary condition to solve an axissymmetric problem Fluent gives me this warning:

Warning: non-positive volumes exist.

this is a picture of my mesh.

Thank you.

When does this error pop up? When you read the mesh, check the mesh, or choose axissymmetric?

For axissymmetric problems, the axis of symmetric is defaulted and can only be set to the x-axis. From your drawing, this seems to be the case.

Non-positive volume error means that you have negative cell volumes. It is a meshing error and you need to correct your mesh. Usually it is caused by bad cells. Not sure how this would pertain though to a 2D mesh.

Sixkillers April 25, 2012 16:17

Also for asymmetrical boundary condition your whole geometry has to be above x axis. When it is not, this message appears. You can quickly fix it by rotating your mesh in Fluent (under Mesh -> Rotate).

A7A April 25, 2012 17:39

Thank you for all of your replies it was so helpful.:)


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