[Technical] 2D Elements in OF

woodwick · June 14, 2013, 02:08

Is it true that in OpenFOAM you cannot create 2D elements?

I would like to simulate a radiator panel with 2D elements and assign to those elements some thermal attributes.
In OpenFOAMwiki (2D Mesh Tutorial using GMSH) I read
OpenFOAM by default only works with 3D mesh elements.
Is it true also for the lastest OF2.2?

additional info:
In this sail-boat simulation I read that they used GMSH too.
(slide 27) the elements of the sail are not directly created in openFOAM
they create the mesh of the sail with "Structural grid generation (surface mesh in 3D space) by gmsh"
then "Conversion from gmsh mesh to openFOAM dictionary by gmshToDict"
But is a paper of 2007. I was wondering if with newer OF releases is there a simpler way?

akidess · June 14, 2013, 03:32

For most purposes yes that's true, you exclusively use 3D elements. Exceptions are patches (boundary faces of a 3D mesh), thermal baffles (see http://www.openfoam.org/version2.2.0/thermophysical.php) and finite area meshes. You are not very clear why you insist on 2D elements, but thermal baffles sounds like what you are looking for.

woodwick · June 14, 2013, 06:27

Thank you Anton.
By the way, the reason why I wanted to use 2D elements is that in the fluid volume I have very very very thin panels of metals. So I was thinking:
1) I could try to mesh those panels with an extrudeMesh, try to obtain very thin elements. But the thickness is so thin compared to the surface that unless extrudeMesh is capable of producing very high aspect ratio elements I would probably end up with some quite heavy mesh, just for some panels that from a volume point of view are negligible. And my machine is unfortunately not so powerful.
2) that's why I was thinking well... if I could use 2D elements it would be a lighter model.
But your suggestion about thermal baffles it's very good. With that I think that I can solve my problem.

June 14, 2013, 02:08	2D Elements in OF	#1
woodwick New Member Alessandro Join Date: Feb 2013 Location: Italia Posts: 15 Rep Power: 13	Is it true that in OpenFOAM you cannot create 2D elements? I would like to simulate a radiator panel with 2D elements and assign to those elements some thermal attributes. In OpenFOAMwiki (2D Mesh Tutorial using GMSH) I read OpenFOAM by default only works with 3D mesh elements. Is it true also for the lastest OF2.2? additional info: In this sail-boat simulation I read that they used GMSH too. (slide 27) the elements of the sail are not directly created in openFOAM they create the mesh of the sail with "Structural grid generation (surface mesh in 3D space) by gmsh" then "Conversion from gmsh mesh to openFOAM dictionary by gmshToDict" But is a paper of 2007. I was wondering if with newer OF releases is there a simpler way? Last edited by woodwick; June 14, 2013 at 02:16. Reason: misspelling

June 14, 2013, 03:32		#2
akidess Senior Member Anton Kidess Join Date: May 2009 Location: Germany Posts: 1,377 Rep Power: 29	For most purposes yes that's true, you exclusively use 3D elements. Exceptions are patches (boundary faces of a 3D mesh), thermal baffles (see http://www.openfoam.org/version2.2.0/thermophysical.php) and finite area meshes. You are not very clear why you insist on 2D elements, but thermal baffles sounds like what you are looking for. __________________ On twitter @akidTwit Spend as much time formulating your questions as you expect people to spend on their answer.

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June 14, 2013, 06:27		#3
woodwick New Member Alessandro Join Date: Feb 2013 Location: Italia Posts: 15 Rep Power: 13	Thank you Anton. By the way, the reason why I wanted to use 2D elements is that in the fluid volume I have very very very thin panels of metals. So I was thinking: 1) I could try to mesh those panels with an extrudeMesh, try to obtain very thin elements. But the thickness is so thin compared to the surface that unless extrudeMesh is capable of producing very high aspect ratio elements I would probably end up with some quite heavy mesh, just for some panels that from a volume point of view are negligible. And my machine is unfortunately not so powerful. 2) that's why I was thinking well... if I could use 2D elements it would be a lighter model. But your suggestion about thermal baffles it's very good. With that I think that I can solve my problem.