CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Mixed cell zone remeshing in FLUENT 12 (http://www.cfd-online.com/Forums/fluent/75204-mixed-cell-zone-remeshing-fluent-12-a.html)

ChesterP April 19, 2010 10:10

Mixed cell zone remeshing in FLUENT 12
 
Hi all,

I can read this from the User's Guide :
Quote:

The available remeshing methods in ANSYS FLUENT work for triangulartetrahedral
zones and mixed zones where the non-triangular/tetrahedral elements are
skipped.
It doesn't seems to work for me. I have two zones :
1/ Hexahedral zone (sweep mesh);
2/ Mixed cell zone (tetrahedral conforming mesh);

So in the mixed cell zone I have pyramids that make transition from HEX to TET elements. The issue is that when the interface between the two zones is moving (compressing the mixed cell zone) I have negative volumes appearing.

I know that I can make wedges instead of hex, make hex with non-conformal interface, make a transition layer with pyramids only etc.. But I want to know why it doesn't work like it is written in the manual.:confused:

Thanks in advance.

yubaibai88 April 23, 2010 03:25

could you tell me why must building a transition zone between tet and hex?

ChesterP April 23, 2010 05:33

Quote:

Originally Posted by yubaibai88 (Post 256031)
could you tell me why must building a transition zone between tet and hex?

Because when you move from an HEX zone to a TET zone, the elements that are making the transition are pyramids. But pyramids are not remeshed by the fluent remeshing algorithm hence they can cause troubles.

yubaibai88 April 23, 2010 08:59

where are the pyramids come?

ChesterP April 23, 2010 09:43

Quote:

Originally Posted by yubaibai88 (Post 256075)
where are the pyramids come?

From the meshing process. It has to close an elementary volume with 1 rectangular face (coming from the HEX mesh) and 3 triangular faces (coming from the TET mesh) i.e. pyramidal element.

yubaibai88 April 23, 2010 10:19

Quote:

Originally Posted by ChesterP (Post 256083)
From the meshing process. It has to close an elementary volume with 1 rectangular face (coming from the HEX mesh) and 3 triangular faces (coming from the TET mesh) i.e. pyramidal element.

I generate the mesh by creating two adjacent zones in which one is tet while the other is hex.set interface as the boundary condition.no pyramid appears.then import the .msh into fluent.creat nonconformal interface.although mesh motion can perform,grid check failed.
how did you model it

snailstb November 1, 2011 07:53

Quote:

Originally Posted by ChesterP (Post 256054)
Because when you move from an HEX zone to a TET zone, the elements that are making the transition are pyramids. But pyramids are not remeshed by the fluent remeshing algorithm hence they can cause troubles.

I do not think pyramids will cause the problem. they will move according to airfoil zone ,wtihout remeshing and distortion.


All times are GMT -4. The time now is 22:02.