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# Hexahedralization: vary number of elements in the three directions

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### Hexahedralization: vary number of elements in the three directions

Posted by Carlos Melendez at November 14. 2012

Hello everybody,

I want to mesh a beam with hexahedrons. After defining its geometry as a box (Dx=1, Dy=0.2, Dz=0.4), I assign the 3D Automatic Hexahedralization.

Choosing any of the options of type distribution, the number of divisions of the mesh is the same in the three directions. I would like to know if it is possible to define the number of elements that the user wants in each direction. I would like to have a larger number of elements in the direction of the beam than in the other two directions.

Carlos

### Re: Hexahedralization: vary number of elements in the three directions

Posted by Saint Michael at November 14. 2012

Hello Carlos

You need to define a sub-mesh on an edge going along your beam, this allows you assigning different algorithm and/or hypothesis than those used for the whole beam.
Assign to the new sub-mesh:
1) Wire discretization algo
2) "Nb Segments" hypothesis = the number of divisions you want along your beam
3) "Propagation of 1D Hyp. on Opposite Edges" hypothesis.

St.Michael

### Re: Hexahedralization: vary number of elements in the three directions

Posted by Carlos Melendez at November 14. 2012

Thank you St. Michael for your quick answer. I get this message when trying to define the sub-mesh. "Geometry objetct is not a sub-shape of the shape to mesh".

I have tried to define a compound of the box and the edge define along the beam and then mesh this compound. I thought that would make the edge be a sub-shape of the compound. But I was wrong. Any advice?

Thanks again!!

### Re: Hexahedralization: vary number of elements in the three directions

Posted by Saint Michael at November 14. 2012

Yes, to define the sub-mesh, the geom object must be a sub-shape of the shape the mesh is defined on. To make a sub-mesh on an edge, you need to explode ( Geom menu New Entity / Explode ) the shape being meshed into edges and to define your sub-mesh on a proper one of those edges.

St.Michael

### Re: Hexahedralization: vary number of elements in the three directions

Posted by Carlos Melendez at November 26. 2012

Thanks! Now it works.