Options... by simon
Posted February 10, 2013 at 22:01 by diamondx
The ICEM CFD Prism algorithm can not move hexa's out of the way as it inflates the prisms. Therefore, you need to make sure that you don't convert tetra to hexa before prism inflation.
With ICEM CFD, there are always other ways...
1) You could try a Hexa (blocking tab) mesh. This would be really easy if you really wanted to do a sphere in a box... What is your real application? Aircraft shapes, wings, etc. are also pretty easy to do with Hexa blocking. It gives a pure hexa mesh very quickly with the best boundary layers possible and it has very low memory requirements (the lowest of any meshing tool I know).
2) You could try hexa core... Personally, I prefer the transitions in the 12 to 1 conversion, but Hexa Core will use less memory (cartesian algorithm). To use it, start with a Tetra prism mesh, but with a large max size in the volume (to reduce the amount of mesh generated in the volume). Then generate prisms... Then go back into Params by parts and set a max size and turn on hexcore for the volume parts you want to have hexa core in... (other hexa core settings are under global params => volume params => Cartesian => Hexa Core.) This will dump your octree tetras (but keep the surface mesh and prisms). It then uses a cartesian algorithm to generate the hexa core of the right size in the volume, which it then steps back a few layers from the pre existing mesh. Then it uses a delaunay algorithm to fill in the gap between the Hexas and Prisms with Tetras...
3) The ICEM CFD Hexa core isn't as good as the TGrid Hexa Core. TGrid is a bit of a memory pig, but if it is all the same to you, you should try it out. TGrid Hexa core is ideal for Fluent in that it supports hanging nodes, even with adjacent tetras (ICEM Hexa Core only supports haning nodes within the Cartesian region, but fails if they are at the surface adjacent to tetras). The TGrid Hexa Core is also able to go to the walls if they are flat.
4) You could try subdividing your geometry into smaller chunks that your memory capacity could handle. Again, the practicality of this would be dependent on the geometry...
With ICEM CFD, there are always other ways...
1) You could try a Hexa (blocking tab) mesh. This would be really easy if you really wanted to do a sphere in a box... What is your real application? Aircraft shapes, wings, etc. are also pretty easy to do with Hexa blocking. It gives a pure hexa mesh very quickly with the best boundary layers possible and it has very low memory requirements (the lowest of any meshing tool I know).
2) You could try hexa core... Personally, I prefer the transitions in the 12 to 1 conversion, but Hexa Core will use less memory (cartesian algorithm). To use it, start with a Tetra prism mesh, but with a large max size in the volume (to reduce the amount of mesh generated in the volume). Then generate prisms... Then go back into Params by parts and set a max size and turn on hexcore for the volume parts you want to have hexa core in... (other hexa core settings are under global params => volume params => Cartesian => Hexa Core.) This will dump your octree tetras (but keep the surface mesh and prisms). It then uses a cartesian algorithm to generate the hexa core of the right size in the volume, which it then steps back a few layers from the pre existing mesh. Then it uses a delaunay algorithm to fill in the gap between the Hexas and Prisms with Tetras...
3) The ICEM CFD Hexa core isn't as good as the TGrid Hexa Core. TGrid is a bit of a memory pig, but if it is all the same to you, you should try it out. TGrid Hexa core is ideal for Fluent in that it supports hanging nodes, even with adjacent tetras (ICEM Hexa Core only supports haning nodes within the Cartesian region, but fails if they are at the surface adjacent to tetras). The TGrid Hexa Core is also able to go to the walls if they are flat.
4) You could try subdividing your geometry into smaller chunks that your memory capacity could handle. Again, the practicality of this would be dependent on the geometry...
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