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Boundary layer addition at corners

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Old   July 21, 2011, 06:51
Default Boundary layer addition at corners
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Ben Vernieres
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Hi everyone,

I'm trying to mesh a wing using snappyHexMesh and have been struggling for quite some time now with the layer addition setup.

This wing has a 1mm thick TE and a square tip so quite a few sharp edges. I'm exporting the geometry in stl from UG NX7 and tried from Rhino 3 too. It didn't change the problem I have.

What is happening is that basically sHM creates a reasonably nice BL around the section of the wing, at the TE too (see pic attached), but, when reaching the tip of the wing, it stops making the layer addition (see second pic attached), to a point that it doesn't even add layers on the tip face.

Now if I change the front wall patch type from "empty" to "symmetryPlane", it does work a bit better (not a lot though) at the tip but then doesn't add layers up to the symmetry plane... (Note that I'm only using "empty" in the meshing process, I later change it back to "symmetryPlane" to run simpleFoam)

I've been playing around with the settings of layer addition in a systematic way but can't find a workaround... Refining or coarsening the mesh doesn't seem to change anything neither (tried from 200k cells up to 4M cells)

I've been looking around in this forum and some others but still can't find a solution for my problem. Lots of threads that are asking similar questions that are not answered too...

Has anyone got a remedy for this by any chance? sHM is a great tool, would be so nice to have this layer addition part to work nicely!

I'm also attaching the sHMDict file.

Looking forward to a solution!

Cheers,

Ben
Attached Images
File Type: jpg TE.jpg (69.2 KB, 88 views)
File Type: jpg Tip.jpg (96.3 KB, 79 views)
Attached Files
File Type: txt snappyHexMeshDict.txt (10.8 KB, 15 views)
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Old   July 26, 2011, 05:13
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Mark Beal
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Ben,

Did you find a solution to this? I'm having a similar problem. I just changed my boat hull simulation to only have half a domain with a symmetryPlane running down the centre-line. Most of my boat is getting the layers it should (and did before), but along the centre-line I lose the boundary layers.

Any thoughts?

Mark
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Old   July 26, 2011, 05:31
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Ben Vernieres
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Hi Mark,

For this issue, I've found that replacing (temporarily) your symmetryPlane by empty does the trick. Once your layers are generated, you can change back to symmetryPlane.

I'm not sure its the correct way to do it but it seems to work more or less ok.

Please refer to this thread: Boundary layer addition at corners with sHM

I've asked this one to be deleted but obviously hasn't been yet!

Regards,

Ben
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