[Technical] Tets Hex fvMesh

juanduque · October 12, 2006, 10:42

Does anyone if there has got to be any special requirement for unstructured tets+hex meshes to be properly constructed to work with FOAM?

The helper constructor for polymesh only asks for the cell shapes and points basically... but it generates boundaries where the tets and hex meet.. any ideas or suggestions?

Thanks in advance!

gschaider · October 12, 2006, 10:54

You mean you have two tets on top of one hex? And it generates a boundary there? This is not surprising. One face can only be between two cells. In your setup to tet-cells "share" one hex-face. I think you'll have to construct a layer of pyramid cells between the hexes and the tets

eugene · October 12, 2006, 11:25

You should be able to use the stitchMesh utility to merge the two sides.

juanduque · October 12, 2006, 11:57

Thank you.

I thought perhaps FOAM with it's "hanging" nodes magic could do something for me (Topologically it's the same ...) but you're right. Thanks for the Idea of the pyramid "layer". The thing is that I'm adapting a very fast mesher we've developed... tets + polyhedral elements... and we thought that perhaps converting those polyhedraes to tets we could easen up the mesh feeding proccess to FOAM.

Stitch mesh is a good idea, but it would make really slow our meshing proccess (that takes a second or so to generate 1-2 millions of hexes...) and speed is our main directive.

Thank you!

eugene · October 12, 2006, 12:06

OpenFOAM uses a polyhedral mesh format, the shape stuff is all legacy and is only there for backward compatibility. I suggest you just keep the polyhdra.

October 12, 2006, 10:42	Tets Hex fvMesh	#1
juanduque New Member Juan Fernando Duque Lombana. Join Date: Mar 2009 Posts: 14 Rep Power: 17	Does anyone if there has got to be any special requirement for unstructured tets+hex meshes to be properly constructed to work with FOAM? The helper constructor for polymesh only asks for the cell shapes and points basically... but it generates boundaries where the tets and hex meet.. any ideas or suggestions? Thanks in advance!

October 12, 2006, 10:54	You mean you have two tets on	#2
gschaider Assistant Moderator Bernhard Gschaider Join Date: Mar 2009 Posts: 4,225 Rep Power: 51	You mean you have two tets on top of one hex? And it generates a boundary there? This is not surprising. One face can only be between two cells. In your setup to tet-cells "share" one hex-face. I think you'll have to construct a layer of pyramid cells between the hexes and the tets __________________ Note: I don't use "Friend"-feature on this forum out of principle. Ah. And by the way: I'm not on Facebook either. So don't be offended if I don't accept your invitation/friend request

October 12, 2006, 11:25	You should be able to use the	#3
eugene Senior Member Eugene de Villiers Join Date: Mar 2009 Posts: 725 Rep Power: 21	You should be able to use the stitchMesh utility to merge the two sides.

October 12, 2006, 11:57	Thank you. I thought perhap	#4
juanduque New Member Juan Fernando Duque Lombana. Join Date: Mar 2009 Posts: 14 Rep Power: 17	Thank you. I thought perhaps FOAM with it's "hanging" nodes magic could do something for me (Topologically it's the same ...) but you're right. Thanks for the Idea of the pyramid "layer". The thing is that I'm adapting a very fast mesher we've developed... tets + polyhedral elements... and we thought that perhaps converting those polyhedraes to tets we could easen up the mesh feeding proccess to FOAM. Stitch mesh is a good idea, but it would make really slow our meshing proccess (that takes a second or so to generate 1-2 millions of hexes...) and speed is our main directive. Thank you!

October 12, 2006, 12:06	OpenFOAM uses a polyhedral mes	#5
eugene Senior Member Eugene de Villiers Join Date: Mar 2009 Posts: 725 Rep Power: 21	OpenFOAM uses a polyhedral mesh format, the shape stuff is all legacy and is only there for backward compatibility. I suggest you just keep the polyhdra.

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