# Node definition in tetrahedral mesh

Hello all!

I want to mesh a solid with tetrahedrons and predefined the location of some internal nodes.

What I have done so far is first define vertices of the body, edges, then faces, afterwards a closed shell from the faces and finally the body. Then Salome meshes the body and therefore additional internal nodes are created. What I want is these nodes include certain nodes with certain coordinates that I want.

In the postprocessing I could move after meshing the nodes that are located next to my desired nodes, but this may cause problems if finite elements overlap.

Can anyone help me please??

Thank you.

Carlos

Hello Carlos!

You need to create vertices (points) at needed locations, add them to your body using Partition( [body],[vertex1, vertex2...]) and compute the mesh using Tetrahedron(NETGEN) or Netgen 1D-2D-3D algorithms.

St.Michael

Hello St. Michael,

Thanks a lot for your quick answer! I have tried to follow your instruccionts, but I don't make it work.

I have tried two things:

- Partition of the solid and additional vertices - Compute mesh of partition using Tetrahedron

- Partition of a closed shell and additional vertices - Generation of body from partition - Compute mesh of body

New nodes generated are not located in the needed coordinates in any of the cases.

Thanks again!

Carlos

Hi,

It seems to be an issue with Netgen-1d-2d-3d. Try to use this combination instead:

- 3D: Netgen 3d

- 2D: Netgen 2D

- 1D: Wire discretisation, local length.

Chrys

Hi Chrys,

Thank you for your answer. I tried your instructions but I don't make it work either. The program stops working.

The only way I have found to have the needed points in the mesh is to choose the algorithm NetGen 1D-2D-3D to mesh the partition. But then I get one error: NgException at Surface meshing: Problem in Surface mesh generation. I get this error for two faces.

Thanks!

Carlos