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tony00 November 24, 2009 19:25

Tgrid hybrid mesh pyramid transition
i am using Tgrid to mesh a volume. These are the steps:
1)I am growing prisms on some faces wihch originally have quad surface mesh.
2) After I create the prisms I create&activate a new domain by selecting the prisms caps and the remaining faces.
3) I will mesh this with tetra. I select pyramid as transition elements before meshing the domain.
4) I mesh with tetra.
When I run the simulation in Fluent the prisms are disconnected from the tetra mesh and no flow goes through.

Back to Tgrid I tried to merge the volume domains (prisms and tetra) but I could only see one domain.

Could anyone see what I am missing? I checked the tutorial on hybrid mesh in Tgrid and do not spot where the problem is.

Thank you

udayrg November 25, 2009 02:07



Well to find out whether the prism layer and the tet domain share a common face. Do as follows

1) Select a node on the prism cap set range to 1 and compute in display grid bounds options.

2) In display grids face option put option all

3) In Attributes display face edges filled you will certainly get if you have two or single face between Prism and tet zones.

If you are advanced user i would say, In simple look for a c/s of the Surface mesh.

Now if the there exist only one surface. You need to merge the prism and tet zones in tgrid and change the prism cap to interior, merge the prism side with adjoining surface. In Fluent it will seperate the zone with connectivity and boundary conditions applied in preprocessor.

try it and let me know if it works

Apart from it if you have two surfaces one with prism and one with tet zone you need to remesh.

tony00 November 25, 2009 06:07

Tgrid hybrid mesh
Hi udayrg
thanks for the reply. It looks like I have two faces so i need to remesh.
Now the question is:
what i am doing wrong in my meshing steps?
How do I generate prisms, pyramids and tetrahedrons which are connected?


udayrg November 26, 2009 02:38

Hi Tony00

You can proceed step by step

1) Develop prism layers

2) On the the prism cap generate pyramid manually i.e. without automesh option

3) Create a domain with the pyramid cap and remaining surface for tet. generation.

4) Merge the prism, pyramid and tet zones in one zone.

5) Merge the prism side in the adjoining surface zone and either you can merge the prism cap and pyramid cap in fluid interior or just apply interior boundary condition.

This will certainly work until and unless you do not have any skewness issue on pyramid transition.

tony00 November 26, 2009 05:36

Prism cap from wall to internal
it does work now with your steps! I also had to change the prism cap from wall to internal. As the wall was stopping the flow.
The commands were:
boundary->manage->change type.

Thank you very much for your help

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