gmsh2nek -- how to use it

[Nadeem Malik]

Hi Neks,

I have generated my own simple cylindrical volume and mesh using gmsh,  in "cylinder1.msh". Now I want to convert it to nek format, for which I believe gmsh2enk would be suitable. But I do not think that its usgae is actually described in detail in the nek5000 documentation. 

I note that there are limitations:

• Unstructured grid GMSH file format 2.x
• A periodic boundary face pair has to match 1:1

My mesh  has about 1.5 million terahedra. I am using the latest gmsh 4.12.2. Furthermore, turbJert stores the mesh at ./turbJet/mesh/jet.exo.

So, how do I install and use gmsh2nek ? How is the *.exo file produced, and how do you obtain the *.rea and/or *.re2 files from this?

Then, what do I enter into SIZE parameters?

Thanks

Nadeem Malik

[Ansh Chaube]

Your mesh needs to have hexahedra, which can be done by extruding transfinite surfaces. The gmsh documentation has more information. You need to set order 2 to get compatible elements.It also needs to be saved as v2 ASCII.

To start using it, you need to compile it with `maketools`. If the bin dir is added to your path, you can start using it from the terminal as any of the other tools.

Gmsh2nek should guide you through the process of mesh conversion and should generate an re2 at the end. BCs still have to be assigned through par/usrdat2.

There's more information here: https://github.com/Nek5000/Nek5000/tree/master/tools/gmsh2nek