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Possible to create cyliner baffle (internal) using topoSet or stl Mesh?

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Old   July 25, 2013, 06:36
Default Possible to create cyliner baffle (internal) using topoSet or stl Mesh?
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David Long
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Hi Foamers,

I am struggling to create internal zero-thickness cylinder wall. Having searched through the forum, but could not find any related posts about how to create curved internal patches.

It seems that topoSet can only select planar faceSet via Box. But how to select cylinder walls via topoSetDict?

So I tried another way to create such internal curved walls: generate the internal cells using 2 volumes via GMSH, and set all the BCs including the internal Cylinder BC (please take a look at the attached Picture as well as the gmsh file ). When convert the msh file using gmshToFoam, the internal BC disappeared.

SnappyHexMesh seems another way to solve this issue. By import all of the surface .stl mesh and using the new feature in OF 2.2.0 like:

Code:
   
refinementSurfaces 
{ 
...
        wallCylInside  // internal cylinder wall 
        {
            level (2 2);
            faceZone wallCylInside;

            // Create baffles for all faces on the surface
            faceType baffle;

            cellZone wallCylInside;
            cellZoneInside inside; 
        }
...
}
but the snapping process failed.

So is there anybody ever faced the same issue, any advice will be appreciated.

Best,

David
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Old   July 25, 2013, 08:20
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Andre Weiner
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Hello,

as i said bevor, the topoSetDict-file in the propeller tutorial is exactly what you need ( if i got your problem right :-)

It's correct that you can't select the faces directly, but you can do some boolean operations, starting with "cylinderToCell" or "surfaceToCell" as source for a cellSet. With the "surfaceToCell" source you can use a .stl-file as input.

Hope i could help you. Good luck!
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Old   July 25, 2013, 09:44
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Artur
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Just to expand a bit on the previous commenter, who I agree with completely: propeller tutorial uses .obj files to snap the mesh to but you can use and .stl file just as well. As far as I remember it is possible to snap the mesh to a searchable cylinder as well but then you can't extract the features from it (not that I know of, at least) so you won't get a very good mesh.
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Old   August 1, 2013, 11:49
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David Long
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Quote:
Originally Posted by andre.weiner View Post
Hello,

as i said bevor, the topoSetDict-file in the propeller tutorial is exactly what you need ( if i got your problem right :-)

It's correct that you can't select the faces directly, but you can do some boolean operations, starting with "cylinderToCell" or "surfaceToCell" as source for a cellSet. With the "surfaceToCell" source you can use a .stl-file as input.

Hope i could help you. Good luck!
After Using snappyHexMesh to generate the internal cells, and then select the internal faces via "cylinderToCell" , delete the redundant faces via "normalToFace". As snappyHexMesh can not exactly capture the sharp edge, the selected internal faces is not perfect but acceptable.



I tried another way to do such job: generate mesh via Gmsh. As the meshes inside the internal Cylinder is created via a single Volume, hence the internal cylinder is perfect:



and the perfect internal faceSet:





Best

Daivd
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