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extrudeMesh - stop edge and cell removal

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Old   August 23, 2011, 06:31
Default extrudeMesh - stop edge and cell removal
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Daniel
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I'm having problems with sweeping a 2D mesh.

I need to change to the threshold for the lengths below which the edges and cells are removed automatically by the collageEdges part of the extrudeMesh utility.

I have altered the mergeDim value in extrudeMesh.C to a very small number (1E-20 * d) but this didn't make any difference and I'm not really comfortable with changing any more code that I don't understand.

Can anybody direct me as to where I can alter this threshold value?

Cheers.

I've attached screenshots of the problems it causes. The first is the 2D mesh I would like to sweep. The second is a clip plane showing the problems that deletion of small volumes causes with the geometry.
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File Type: jpg plane_mesh.jpg (47.1 KB, 32 views)
File Type: jpg Screenshot2.jpg (50.0 KB, 31 views)
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Old   August 23, 2011, 06:39
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Daniel
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A little more info:

When I run extrudeMesh I get the following type of message:

Code:
Merging edge (8530 8531) since length 0 << 0.042625
In this case, the 0 refers to the removal of the edges created at the axis of rotation (I assume). It is the value of "0.042625" I would like to alter.
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Old   August 23, 2011, 08:53
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Converting the mesh to metres from mm was a good start. However, I'm still having problems with the small volumes in the boundary layer, close to the axis of rotation.

Last edited by drrbradford; August 23, 2011 at 09:22.
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Old   August 24, 2011, 11:19
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I've solved the problem and have learned a tiny bit about programming while I've been at it.

For anyone who needs to deal with this in future:

1. Change mergeDim value in the file /OpenFOAM-X.Y.Z/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C to some appropriate value. Don't make it too small if you still want to remove the singularities created at the axis of symmetry.

2. Delete the file applications/utilities/mesh/generation/extrude/extrudeMesh/Make/<PLATFOM>/extrudeMesh.o

3. Open a terminal in the applications/utilities/mesh/generation/extrude/extrudeMesh/ directory and run wmake.

Boom, threshold changed.
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cell volume, extrudemesh, revolved mesh

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