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ali987 December 18, 2009 04:52

[ICEM] Generate Pyramid elements

I'm completely beginner with Ansys ICEM. I could mesh a cube by tet or hex elements(by try and false). but i want to mesh a part of the cube by tet, another part by hex and connect this two parts by pyramid. could you please help me how to do these tsep by step?

it is important for me that all pyramid elements be exactly the same with height of "h" and square base of 2h.


PSYMN December 19, 2009 16:52

Tet to Hex merge.
Look for a tutorial on tet to hex merging... There is an HVAC example you could try.

Basically you mesh each half of the cube with one of the methods and then merge them at the interface surface.

Should be simple after completing a couple tutorials on your own.


ali987 December 20, 2009 14:35

thanks for your guidance PSYMN.

I do that, but I still have 2 problem:

1) When I export mesh, information for pyramidal elements doesn't export!!!

2) some of the pyramids are not uniform. I want to have pyramid with their vertex(image) exactly located on the middle of the base and it's height be half of the base length(square base). in other word I want to have control on all pyramid elements....


PSYMN December 21, 2009 01:16

No idea why they don't export, it could be that your solver format doesn't support them or who knows what... I can tell you that most users have no trouble exporting pyramids to a variety of solvers, so my first guess would be to take another look at your steps;)...

Also, ICEM CFD is not designed for meshing cubes... It is designed form meshing real world geometries that sometimes get a little messy. Its pyramids are not rigid, they flex to give the best quality for the situation. usually, they strive to be ideal as you describe, but the quality and volume of adjacent elements is also taken into account and may adjust the results...

If your requirements are really so rigid, you may need to create things more manually... You could use ICEM CFD to create one layer of Hexas with pyramid caps, make sure it is perfect (Create a series of points at the right locations relative to the hexa mesh size and make sure the pyramid tips are at those locations...), and copy it up, then fill in the tetra portion... Or you could just write a bit of code to fill a cube perfectly as you describe (create the uns file or *.msh file explicitly for this one cube case...)

It may take a bit more effort to meet your requirement... Which leads to the question of "how important is the requirement?"

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