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-   -   Meshing Sudden Contraction and Expansion (http://www.cfd-online.com/Forums/ansys-meshing/74024-meshing-sudden-contraction-expansion.html)

carldaru March 23, 2010 01:01

Meshing Sudden Contraction and Expansion
 
Hello,

I am trying to mesh a 2D sudden contraction and expansion using Gambit. However, I am not sure what type of meshing to use. Every type except "Quad Pave" keeps kicking up some sort of error for me. Either it's too skewed, or if I try using triangles, the triangles are too big, or I get a negative volume, etc. When I used "Quad Pave," the analysis that came out was not what was expected. Is it possible to mesh 2D figures that have a conical contraction and sudden expansion with plain cartesian meshes that literally go parallel and perpendicular to the length of the pipe in a perfect grid pattern (i.e. a 10 x 100 grid). If the perfect cartesian grid mesh is not possible, what type of meshing do you guys suggest I use? Also, do I just mesh the face or just the edges, or both?

Also, when I want to turn this into 3D, do I just do a revolve and then use the same type of mesh? Would that work, or is something else needed?

Thank you.

-mAx- March 23, 2010 01:56

you can control the mesh refinment with size functions.
In 2d I assume you can handle your problem with quads. (maybe you need to split your domain to achieve it)
you may post a picture.
Regarding 3d model, then you can revolve your faces, hex-cooper meshing schema should be enabled (just take care with face connectivity)

carldaru March 24, 2010 13:28

1 Attachment(s)
Quote:

Originally Posted by -mAx- (Post 251196)
you can control the mesh refinment with size functions.
In 2d I assume you can handle your problem with quads. (maybe you need to split your domain to achieve it)
you may post a picture.
Regarding 3d model, then you can revolve your faces, hex-cooper meshing schema should be enabled (just take care with face connectivity)

So by "size functions", I assume you are referring to the interval count/interval size controls? If I wanted a grid of say 10 x 100 (100 lines perpendicular to the length of the pipe), then would I select the edges appropriately and just type in 10 and 100?

When you say "split your domain", what are you referring to, and how does one go about doing that?

Once I get the 2D meshing down I will try the 3d model with the hex-cooper meshing. I assume face connectivity has to do with the splitting of the domain as referenced above? Am I correct in saying this?

A picture is posted with this message.

Thank you.

-mAx- March 25, 2010 02:55

1 Attachment(s)
In your case, just split your domain into logical and mappable surfaces.
See the picture (I just meshed one half (upper) side)
Attachment 2678

hassan79 April 13, 2010 13:02

need help
 
which turbulent model used can i have your mobile no


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