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-   -   reduce 3D to 2D mesh (http://www.cfd-online.com/Forums/openfoam-pre-processing/116544-reduce-3d-2d-mesh.html)

Natalie2210 April 22, 2013 04:21

reduce 3D to 2D mesh
 
Hi everybody,

I have a rather strange problem, namely, I have a 3D geometry but I want to perform a 2D simulation based on it. It would be a start if I could use the setSet or a similar utility to extract only my boundary faces (at one side) and use that as my 2D mesh, but I really don't know how to start - has anyone done this before? Or is there another way to get a 2D geometry?

Thanks a lot,
Natalie

A.Wendy April 22, 2013 05:48

how do you create your mesh before. in snappyhexmesh you can for example also create a 2d mesh when the front and back faces are empty and nly 1 cell in the depth.

Natalie2210 April 22, 2013 06:27

Hi!

I export my mesh from Altair Hypermesh. It provides the possibility to export geometry in an OF format, but, as far as I know, for this option I need a tetrahedral volume mesh.

SnappyHexMesh exports also a 2D geometry to every 3D geometry it creates? Maybe I should write to the Hypermesh support and ask whether this option is also available in Hypermesh.

Kind regards,
Natalie

A.Wendy April 22, 2013 07:06

if you want to run a 2d simulation and want you use snappyhexmesh for meshing. you only have to be sure that your patches are defined the right way. so you can run snappy hexmesh and get no refinement in the third dimensiobns. what does your mesh in your third dimension looks like? if you only have 1 element you should run a 2d simulation by setting the front and back face to "empty"

ngj April 22, 2013 15:01

Hi Natalie,

Potentially, you could use the utility "extrudeMesh", which are located in

Code:

<OpenFOAM>/applications/utilities/mesh/generation/extrudeMesh
and the description reads:

Code:

    Extrude mesh from existing patch (by default outwards facing normals;
    optional flips faces) or from patch read from file.

    Note: Merges close points so be careful.

    Type of extrusion prescribed by run-time selectable model.

Best regards

Niels

Natalie2210 April 23, 2013 04:16

Actually, I have only 1 element in the third direction and I've tried just setting the front and back face to empty.. seems I got it wrong somehow, I will have a look at the tutorials.

@A Wendy:
Can I import my 3D geometry into snappyHexMesh and get somehow a 2D mesh by extracting patches? Or what do you mean?

Thanks a lot,
Natalie

A.Wendy April 23, 2013 06:08

Quote:

Originally Posted by Natalie2210 (Post 422515)
Actually, I have only 1 element in the third direction and I've tried just setting the front and back face to empty.. seems I got it wrong somehow, I will have a look at the tutorials.

@A Wendy:
Can I import my 3D geometry into snappyHexMesh and get somehow a 2D mesh by extracting patches? Or what do you mean?

Thanks a lot,
Natalie

hi sorry i mixed something. if you want to create a 2d mesh with snappyhex mesh you have a 3d mexh first and can use extrudeMesh to create a mesh with 1 element in the depth. but if you do not set the front and back in the blockMeshdict snappyhexmesh will not create a clean front face.
you can have a look a at this example I created
http://ubuntuone.com/722FQ4i7HA8A6KVDsVbYs4

best wishes

Andy

Natalie2210 May 2, 2013 02:37

Hi!

I'm afraid my browser does not find the homepage you posted a link to .. could you copy the example somehow into this forum?

Thanks,
Natalie

A.Wendy May 2, 2013 03:37

Quote:

Originally Posted by Natalie2210 (Post 424556)
Hi!

I'm afraid my browser does not find the homepage you posted a link to .. could you copy the example somehow into this forum?

Thanks,
Natalie

hi,

i cleaned up my webspace. here is the new link

http://ubuntuone.com/3kPBj7ob4yfD8bcHMzZyFK


Andy


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