interFoam with irregular Mesh

luther · July 21, 2009, 10:09

Hallo,

Is it possible to use interFoam with a tetrahedral mesh or is it only designed for hexahedral meshes.

I can get a simple case to run with tetra, but it crashes after a while. With the same geometry and input conditions, but with a hex mesh it works fine.

All the examples and other work I see of interFoam is with hex meshes.

If someone can please shed some light I would appreciate it.

Kind Regards
Luther

ngj · July 21, 2009, 10:56

Hi Luther

From the point of view of OpenFOAM, I cannot see any limitations in interFoam, hence it must be a problem with your setup, which makes it unstable with tets.
If you could describe your problem in more details, e.g. with figures, I might be able to help.

Best regards,

Niels

ulli · July 21, 2009, 11:15

Hi Luther,

also from my experience interFOAM works much better with hex-meshes than with tet-meshes. I think one reason is that the element growth rate in tet meshes can be rather high. So I made better experience with tet meshes providing a smoother transition (propagation rate). But this may result in rather large meshes...

Ulrich

luther · July 21, 2009, 11:34

Thank you Niels,

I will have a thorough look at my setup again and if the problem stil persists I will mail you the case and you can see if you find anything wrong.

Kind Regards
Luther

awacs · July 21, 2009, 23:54

Hi Luther,

I met the same problem when using the interFoam solver. The result was ok with hex-meshes. When I used tet-meshes for the same case, the courant number became bigger and bigger, then the calculation stopped.

Maybe, it is caused by the non-uniform tetrahedral mesh. I will pay more attention to it.

If there are any new developments, please let me know.

Kind Regards
Jitao

Schag · July 22, 2009, 03:53

Hi Luther,

I use almost every time interFoam for my work. At first, I tried it only with hex mesh, and had no issue.
Then I tried the same cases with tet mesh. At first it crashed, but since I pay more attention in meshing, I do not face this kind of problems. So be carefull in meshing and there is no reason your simulation crashes because of mesh (I think...)

Regards

Julien

sega · July 22, 2009, 05:23

My experience with non-orthogonal grids is to make sure you use corrected schemes!

You can also try to increase the number of non orthogonal corrector loops (nOrthogonalCorrectors).

albcem · August 14, 2009, 02:20

Don't waste time with tetrahedral grids for the interFoam class solvers by playing with correctors, schemes and etc. I wasted weeks trying to get things to work with tets and results were far from satisfactory = the effort is not worth it. Just go with hexes if you can.

luther · August 14, 2009, 03:43

Thank you. I have the same experience. Do you perhaps know about any literature where I can read up on the cause of this phenomenon?

sega · August 14, 2009, 08:43

Quote:

Originally Posted by luther

Thank you. I have the same experience. Do you perhaps know about any literature where I can read up on the cause of this phenomenon?

I have posted some literature reference on this problem here:
http://www.cfd-online.com/Forums/ope...-than-tet.html
It's post #9 ...

July 21, 2009, 10:09	interFoam with irregular Mesh	#1
luther New Member Luther Terblanche Join Date: May 2009 Posts: 15 Rep Power: 17	Hallo, Is it possible to use interFoam with a tetrahedral mesh or is it only designed for hexahedral meshes. I can get a simple case to run with tetra, but it crashes after a while. With the same geometry and input conditions, but with a hex mesh it works fine. All the examples and other work I see of interFoam is with hex meshes. If someone can please shed some light I would appreciate it. Kind Regards Luther

July 22, 2009, 05:23		#7
sega Senior Member Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 20	My experience with non-orthogonal grids is to make sure you use corrected schemes! You can also try to increase the number of non orthogonal corrector loops (nOrthogonalCorrectors). __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

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July 21, 2009, 10:56		#2
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,903 Rep Power: 37	Hi Luther From the point of view of OpenFOAM, I cannot see any limitations in interFoam, hence it must be a problem with your setup, which makes it unstable with tets. If you could describe your problem in more details, e.g. with figures, I might be able to help. Best regards, Niels

July 21, 2009, 11:15		#3
ulli Member Ulrich Heck Join Date: Mar 2009 Location: Krefeld, Germany Posts: 41 Rep Power: 17	Hi Luther, also from my experience interFOAM works much better with hex-meshes than with tet-meshes. I think one reason is that the element growth rate in tet meshes can be rather high. So I made better experience with tet meshes providing a smoother transition (propagation rate). But this may result in rather large meshes... Ulrich

July 21, 2009, 11:34		#4
luther New Member Luther Terblanche Join Date: May 2009 Posts: 15 Rep Power: 17	Thank you Niels, I will have a thorough look at my setup again and if the problem stil persists I will mail you the case and you can see if you find anything wrong. Kind Regards Luther

July 21, 2009, 23:54		#5
awacs Member Jitao Liu Join Date: Mar 2009 Location: Jinan , China Posts: 64 Rep Power: 17	Hi Luther, I met the same problem when using the interFoam solver. The result was ok with hex-meshes. When I used tet-meshes for the same case, the courant number became bigger and bigger, then the calculation stopped. Maybe, it is caused by the non-uniform tetrahedral mesh. I will pay more attention to it. If there are any new developments, please let me know. Kind Regards Jitao

July 22, 2009, 03:53		#6
Schag Member Julien Schaguene Join Date: Apr 2009 Location: France Posts: 55 Rep Power: 17	Hi Luther, I use almost every time interFoam for my work. At first, I tried it only with hex mesh, and had no issue. Then I tried the same cases with tet mesh. At first it crashed, but since I pay more attention in meshing, I do not face this kind of problems. So be carefull in meshing and there is no reason your simulation crashes because of mesh (I think...) Regards Julien

August 14, 2009, 02:20		#8
albcem Member Cem Albukrek Join Date: Mar 2009 Posts: 52 Rep Power: 17	Don't waste time with tetrahedral grids for the interFoam class solvers by playing with correctors, schemes and etc. I wasted weeks trying to get things to work with tets and results were far from satisfactory = the effort is not worth it. Just go with hexes if you can.

August 14, 2009, 03:43		#9
luther New Member Luther Terblanche Join Date: May 2009 Posts: 15 Rep Power: 17	Thank you. I have the same experience. Do you perhaps know about any literature where I can read up on the cause of this phenomenon?