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nileshjrane August 11, 2010 14:48

Meshing a pipe joint for OpenFoam--Hex or Tet????
Hello all,
I am a newbie to OF. I want to solve a mixing problem in a pipe geometry with 2 inlet ducts. See the image attached. Final geometry is bit more complicated and this is just a simplification.

Is it possible to make hex mesh for such geometry with some free meshing software?? I have been trying out all those i could find. Its not trivial to use o-grid as well as it wil cause problem near the junctions. If anyone can tell me how to do this, it would be great.

Also its easier to get a free tet mesh for this geom from Salome. But i have a doubt there too that whether hex mesh is better or tet as far as OpenFOAM is concerned.

If someone could help me in getting hex mesh it would be really life saving for me as i really want to avoid Gambit for this..

marcbest August 12, 2010 06:17

hi nileshjrane,

at the end the solution of your calculation should be mesh-independent, so i does't matter which one you take - hex or tet. as openfoam is a face based solver hex has a better cell/face ratio so calculations with hex mesh can be faster.
if you want to use tet in salome see this:
i don't know if in salome the 3D hex, 2D radial quadrangle works with junctions...
another way would be snappyhexmesh which is a bit difficult to lern but offers good refinement options for hex mesh, see:

i hope this helps

nileshjrane August 12, 2010 15:54

@Mercbest :

Thanx for ur reply.

I am very new to openfoam. But i have lot of CFD experience. Just dont know how to wield OpenFoam. So please excuse my stupid questions.

Can i do this?? Importing only geometry (.stl) from Salome and make a hex mesh in snappyHexMesh???

One more thing, whatever i have seen, SnappyHexMesh is used for extrnal flows?? Is there any tut or something for internal flow meshing??

marcbest August 13, 2010 08:40

no problem, i had the same questions when i started with OF

you can do internal flows with snappyhexmesh and stl-files:

but unfortunately there are no good tutorials for internal flow... that's why i did not start using snappyhexmesh
another point is that snappyhexmesh creates bad edges so you would need this program:

for all the free mesh programmes you need at least one week to become familiar with them...

nileshjrane August 14, 2010 05:38

hello again,
I want a mesh like this one from the post:

I want the boundary layer as well with this mesh.

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