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-   -   Help to mesh in Gambit please (http://www.cfd-online.com/Forums/fluent/46135-help-mesh-gambit-please.html)

Nicolás September 25, 2007 12:53

Help to mesh in Gambit please
 
Hi, Somebody could help me please,

I can not mesh a curved pipe. I make a square in the centre of the face, than I project this face to the other face and I mesh first a face with Cuad elements and Map type, than I mesh the total volume with Map Type and Hex elements . This step work well for lineal pipe, but not in curved pipe..I have problem whit the curves, because the points dont adapt themself to the edge of my pipe, they follow other line.. Maybe I must use other technique, anybody could know how can I mesh it ?

thanks very much.

Vinod Dhiman September 25, 2007 13:39

Re: Help to mesh in Gambit please
 
Hi

The best way to mesh a volume is cooper. The only limitation cooper scheme has it that the face on which it is being projected should not have any face in between it, i.e., a face of smaller size within the face. Else, it doesn't matter whether the volume is curved or straight, cooper will work. Just mesh one face of pipe, use map if possible else pave, then use Hex and cooper scheme to mesh the volume. Source faces will include all faces except the curved face, i.e., the curved surface of pipe.

Nicolás September 25, 2007 14:29

Re: Help to mesh in Gambit please
 
Hi Vinod,

Thanks for your help!

I have made the mesh with the cooper tool, but this way need a lot CPU time, approx 3,5 hours (maybe my computer is old). My pipe is 2,34 m long and a radio of 0.002 m. You say that I mesh one face, but I can not make subfaces in the original face? but how could I make a square face within a circular face? because this form is a better form to mesh circle, or not?

Regards,

Nicols

AAA September 25, 2007 22:27

Re: Help to mesh in Gambit please
 
Hi

Don't leave it to Gambit to choose the interval size along the span of the pipe. The used interval size might be too small and that's why you are using large CPU. You must control the node number on the span of the pipe. After meshing one face, and before performing the Cooper scheme, go ahead and mesh the span of the pipe (Not the entire face) with large enough intervals. Now the Cooper scheme will follow your interval size.

I hopr this helps!

AAA

Nicolás September 26, 2007 09:39

Re: Help to mesh in Gambit please
 
Hi AAA and Vinod, thanks for your interest!

AAA, this is exactly that I have made, I choose the interval size along the span of the pipe, but always the CPU time is very long.

I mesh one face with 145 and than the volume with cooper tool, with 1000 points in each edge along the span of the pipe..so I can obtain 145000 cells in total.

the dimension of the pipe is 2,34 meters long and 0,002 mm radio.

Regards,

Nicols

AAA September 26, 2007 12:56

Re: Help to mesh in Gambit please
 
Hi

145000 cells is too much for a 234 cm pipe of 2 mm radius. Are you trying to resolve the properties of the wall?

What happens when you mesh one face with less cells (w/ Cooper)? What happens when you mesh the entire domain with tri-elements (w/o Cooper)?

Regards

AAA

nicolas September 26, 2007 14:07

Re: Help to mesh in Gambit please
 
Hi, No, I dont try to resolve the properties of the wall, I want to analyse what happens in each 1 mm through the pipe, but in the contain of the pipe. (milk) When I mesh how you told me, Fluent recognise a volume negative (WARNING: non-positive volumes exist)..

(When I import the geometry in Gambit (from Rhinoceros), I think that the figure is a little bit strange, because I obtain a geometry with corners instead curved)

Regards,

Nicols


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