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What is the easiest way to create a 2D blockMesh with a triangular cut-out?

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Old   June 7, 2018, 15:37
Default What is the easiest way to create a 2D blockMesh with a triangular cut-out?
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Axel
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Hi everybody!

I am trying to get a rather simple 2D mesh, that is basically a rectangular 2D fluid domain with a triangular cut-out in the middle of it, where I can easily change the coordinates of the triangle's points.

How can I create such a mesh? I thought about using a topoSet but I couldn't find an option for triangular sets there.

Best regards,
Axel
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Old   June 8, 2018, 02:21
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Not sure if this is what you are looking for, but you could use a variable at the top of blockMeshDict for the location of the points of the triangle to conveniently change the geometry of the triangle quickly. If the size of the rectangle is also depending on the triangle it is also possible to make their location dependent on the triangle size etc.
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Old   June 8, 2018, 02:49
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Hi Bazinga,

thanks for your reply! Yes this is part of the solution I am looking for. However right now I was not even able to get a blockMesh for 3 fixed points.

So first I would need some advice on how to get the cut-out with a fixed triangle, then I would take your advice to use the variables in blockMeshDict.

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Old   June 8, 2018, 03:45
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I did not try a triangle yet, but blockMesh should be capable of doing it as you can create blocks with fewer than 8 vertices (check in the user guide "5.3.5 Creating blocks with fewer than 8 vertices").
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Old   June 8, 2018, 03:54
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Ok, but how would I use the triangle blockMesh to make a cut-out inside a rectangular blockMesh?
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Old   June 8, 2018, 04:00
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Go the extra mile, if you're blockMesh-masochistic enough.

In that case, you can use moveMesh to rotate the red mesh region into any orientation you like. Afterwards, use AMI or stitchMesh to create single mesh region.
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Old   June 8, 2018, 04:02
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Is this maybe working? (see attachement)
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siamak 60 likes this.
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Old   June 8, 2018, 04:04
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Hello Gerhard,

this is not exactly what I need as I believe in your case the shape of the triangle would be fixed, right?

Best regards,
Axel
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Old   June 8, 2018, 04:05
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Hi Bazinga!

That looks very promising! I will try something like this as soon as I come home.

Best regards,
Axel
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