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polyDualMesh results in non-planar faces and non-convex cells

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Old   September 13, 2012, 08:47
Default polyDualMesh results in non-planar faces and non-convex cells
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Tomislav Maric
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Hi everyone,

I have an extremely simple domain: a box of dimensions [0,1]^3 which is meshed with tetrahedrons using the Netgen algorithm of Salome (version 6.4.0, 64 bit). When I use the polyDualMesh to generate a polyhedral mesh of the boxed domain, I get cells which are non-convex and have non-planar faces. Here is a picture of such a cell.

I've tried multiple feature angles, although the 90 degrees seems most sensible for a simple box domain. Any advice on this?

Here's the case with the .unv of the tetrahedral mesh.

Note: creating a more regular tetrahedral mesh using a decomposition of hex cells results in a combination of hex-poly cells, where the polyhedra are convex with planar faces, but the cell aspect ratio is kind of high (around 2).

Is there a way to get a good polyhedral mesh using purely tet mesh generation algorithms such as Netgen?

Last edited by tomislav_maric; September 13, 2012 at 09:33.
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Old   September 13, 2012, 10:18
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Sandeep Menon
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Have you checked to ensure that your underlying tet-mesh is Delaunay? If not, you'll have to ensure that first.

Of course, you could easily pre-process the underlying tet-mesh (with smooth/remesh) before you convert it to polyhedra..
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Old   September 13, 2012, 10:24
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Quote:
Originally Posted by deepsterblue View Post
Have you checked to ensure that your underlying tet-mesh is Delaunay? If not, you'll have to ensure that first.

Of course, you could easily pre-process the underlying tet-mesh (with smooth/remesh) before you convert it to polyhedra..
Thanks! Nope, didn't check this.... I'm working with Salome, so I'm not sure how it goes about generating tet meshes..

As for smoothing-remeshing: how can I be sure that the dual will result in convex cells? I mean, what parameters/workflow do I use for smooth/remesh in this case?
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Old   September 13, 2012, 10:29
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I typically use the mesquiteMotionSolver in combination with moveDynamicMesh for a few time-steps. If you want to remesh as well, you can use dynamicTopoFvMesh (which can include a smoother as well).

Sorry for blatantly advertising my stuff, but couldn't help it...
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Old   September 13, 2012, 10:32
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Tomislav Maric
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Quote:
Originally Posted by deepsterblue View Post
I typically use the mesquiteMotionSolver in combination with moveDynamicMesh for a few time-steps. If you want to remesh as well, you can use dynamicTopoFvMesh (which can include a smoother as well).

Sorry for blatantly advertising my stuff, but couldn't help it...
Hehehehe marketing is always good.. and your stuff is worth advertising, so no worries there! Thanks for the info, I will try it!
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