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joe September 8, 2005 06:43

problem in mesh linking
Sir, I am working on flow inside a pipe which has threads, so i have modeled the cylinder as a single volume and meshed it by cooper mesh and modeled the helical part and meshed it by tet/hybrid. now i have to import it to fluent . So i want both to be as one part that is to be as single mesh. Instead of it as two volumes. how should i do it .is it by modeling it as single volume and decomposing it. if so how should i do it because if i work it by uniting them and working on it is difficult as problem arises in mesh. how to link two similar or different geometry mesh and make it as single volume.

thank you

Jason September 8, 2005 09:22

Re: problem in mesh linking
If both volumes are in the same Gambit file, then you can apply a non-conformal grid interface on the zones. The face of the cylinder that touches the helical volume I will call Face A, and the face of the helical volume that touches the cylinder I will call Face B (Face A and Face B can be made up of multiple faces as well, I'm just calling them one face for simplicity).

In Gambit, assign "interface" BC to Face A and call it whatever you want (something representative... like "interface_A" works nice), and assign "interface" BC to Face B ("interface_B" for example). Then in Fluent go to Define->Grid Interfaces. Pick "interface_A" under Interface Zone 1, and "interface_B" under Interface Zone 2, then give it a name and click Create (Don't turn on any of the interface type options).

If they aren't in the same Gambit file, then you'll have to use TMERGE. I'm not familiar with it, but the non-conformal grid interface tutorial uses Tmerge, so you can use that to help you along.

Either way, you want to be careful that there isn't a radical difference in mesh size between the two volumes. I've been told the non-conformal grid interface can handle a mesh size difference of 2 to 3 times, but I wouldn't recommend anything over 1 to 1.5 times. This will help limit your numerical error in the simulation.

Hope this helps, and good luck, Jason

Masood September 12, 2005 13:24

Re: problem in mesh linking
hi joe threads means grooves? if yes then model it in some CAD package. then import it in GAMBIT and do the meshing. if u want to make diffrent volumes split them in GAMBIT it will not unlink them and mesh of the two volumes is linked automatically.

let suppose i understand the porblem correctly. :)


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