Be careful about SnappyHexMesh. You can use it to make hex-only meshes, but it will generate a tesselated mesh (which does not really conform to the boundary, it is by all means a voxel mesh). If you fully use Snappy, it will generate a polyhedral mesh with as many as 20 faces per element. This is all fine and dandy for FVM (like OpenFOAM), but it will not work within deal.II.
On Friday, September 25, 2020 at 4:36:21 p.m. UTC-4 Jean-Paul Pelteret wrote: > Oh, and and just in case you’ve not heard of it before and it might be > useful, there’s also this tool that does automated hex meshing: > > https://www.openfoam.com/documentation/guides/latest/doc/guide-meshing-snappyhexmesh.html > > I’ve never used it though, and I have no idea how you would get the mesh > in and out of OpenFOAM, and whether one can prevent the creation of meshes > with hanging nodes. Nevertheless, maybe its worth looking into. > > Best, > Jean-Paul > > On 25 Sep 2020, at 21:58, Jean-Paul Pelteret <jppel...@gmail.com> wrote: > > Since you have access to Cubit/Trellis, “that patch” is probably not > necessary. Cubit uses the Mesquite library for mesh quality improvement, so > if you could try to increase the mesh quality that way. Although I’d have > to agree with Wolfgang that it might not help too much in this case, but > that’s an educated guess. > > Best, > Jean-Paul > > On 25 Sep 2020, at 15:04, Wolfgang Bangerth <bang...@colostate.edu> wrote: > > On 9/25/20 4:58 AM, Paras Kumar wrote: > > In the quest of alternative solutions, I came across the Mesquite library > and was curious to know if that could be helpful to improve the quality of > the Delaunay based Hex mesh so as to avoid the issue with stress > irregularities. > It also seems that Mequite's integration within deal.II is under progress[ > https://github.com/dealii/dealii/pull/5971]. \ > Since, I have no prior experience with this library, some guidance wrt the > current issue would be of great help. > > > You could try that patch (though I don't know the current status of it -- > the issue is that Mesquite is no longer maintained). > > But I suspect that it will not help very much. You can understand this in > 2d: Even if you have a perfect triangular mesh and then subdivide each > triangle into 3 quadrilaterals, you end up with quadrilaterals shows shape > can not be improved by moving around nodes. Furthermore, and that seems to > be the key issue for theoretical reasons too complicated to discuss here, > you really want 2d meshes where at the majority of nodes 4 quadrilaterals > come together. But the quadrilateral mesh you get out of subdividing > triangles has nodes where either 3, 4, or 6 quadrilaterals come together > (corresponding to triangle centers, triangle edge midpoints, and triangle > vertices). You end up with much higher errors on these kinds of meshes, and > I think that is what you are seeing. Libraries like Mesquite optimize the > mesh by moving around nodes, and that has no effect on the valence of nodes. > > (I'm sure Mesquite can also do other operations, but they are far more > complicated on quad and hex meshes and I don't think the interface enabled > that.) > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > www: http://www.math.colostate.edu/~bangerth/ > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- You received this message because you are subscribed to the Google > Groups "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to dealii+un...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/f4460ec5-52b8-243c-3e34-63cc4171454c%40colostate.edu > . > > > > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/7db082e1-e821-4927-bc74-4aa8ccc0db3fn%40googlegroups.com.
