Question about tetrahedral element types

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awa5114
Posts: 43
Joined: Thu Jan 26, 2017 5:10 pm

Question about tetrahedral element types

Post by awa5114 »

I have a .dat file created by a third-party problemtype which I did not design. I do not have the complete GiD project. I am reconstituting the geometry using tcl native commands to read the .dat file and GiD_Process commands to draw the geometry. The .bas file for the problemtype I am using loops over elements and outputs their connectivities as follows:

*loop elems
*ellemsconec
*end elems

which outputs lines in the dat file as follows:

....
195 176 198 177 185 188 197 184 175 187
415 419 394 382 417 408 406 397 398 391
626 600 622 608 613 609 623 616 603 612
...

for quadratic elements (Mesh>Quadratic Type>Quadratic).

I am re-creating these elements one-by-one using tcl (Mesh>Edit Mesh>Create Element>Tetrahedra) or:

GiD_Process Mescape Meshing EditMesh CreateElement Tetrahedra 195 176 198 177
GiD_Process Mescape Meshing EditMesh CreateElement Tetrahedra 415 419 394 382
GiD_Process Mescape Meshing EditMesh CreateElement Tetrahedra 626 600 622 608

The problem is now the intermediate nodes (last 5) are not part of the elements anymore and still appear as independent nodes in the mesh. The mesh however was created using the same element type as I am now editing it. How can I include the intermediate nodes even though it is a Quadratic type element?
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escolano
Posts: 1918
Joined: Sun Sep 05, 1982 10:51 pm

Re: Question about tetrahedral element types

Post by escolano »

Instead of the process commands you can use more direct GiD_Mesh GiD-Tcl command (see GiD help on Customization->Tcl and Tk extension->Special Tcl commands->mesh)

GiD_Mesh create node <num>|append <x y z>
GiD_Mesh create element <num>|append <elemtype> <nnode> <N1 ... Nnnode> <radius> <nx> <ny> <nz> ?<matname>?

e.g.

GiD_Mesh create element append Tetrahedra 10 195 176 198 177 185 188 197 184 175 187
(the first 10 is for the 10-noded quatratic tetrahedra)

or probably it will be more efficient (without a lot of calls to Tcl commands) to write with Tcl the node/elements in a GiD ASCII mesh file, and then import it in GiD with
GiD_Process Mescape Files MeshRead $filename escape
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