Trelis or Cubit

Recently I’m using openmc to build a complex model, and I want to use dagmc to help me .I found that I must use Trelis or Cubit, but their register fee is too expensive. I wanna is there any succedaneum I can replace the Trelis or Cubit? For I thought I only want to use them to export “h5m” files.

Hi @Jiayelee. As far as I’m aware Trelis/Cubit is the only way to do it currently. I know there is interest in having a fully open source (or at least free) workflow for this but I don’t think it’s come to fruition yet. @pshriwise might be able to say more on this.

Hi @Jiyalee. Thanks for your interest in DAG-OpenMC!

As @paulromano said, Trelis or Cubit is the primary source for DAGMC files. This is primarily because Trelis/Cubit provide overlap checking along with the imprint and merge operations that allow one to export robust DAGMC models. It also provides a way for metadata (primarily material assignments) to be exported with the DAGMC file. More info can on this can be found at the DAGMC website.

There are, however, alternatives for creating DAGMC geometries if the model has the right characteristics. It’s just significantly more involved. Many CAD tools can export STLs of bodies in the CAD engine. As long as these model volumes are disjoint, non-overlapping, and don’t have coincident surfaces individual STLs can be compiled into a single DAGMC geometry. Here is a script which will do just that using the Python interface to MOAB (PyMOAB). Here, material assignments are added to the DAGMC file using an associated JSON file. Another DAG-OpenMC user was able to use this workflow successfully with FreeCAD.

Realistically, models often quickly become too complicated for this STL workflow and the features of Trelis/Cubit are necessary to generate the DAGMC files needed (again, primarily for the ability to handle coincident surfaces with the imprint and merge features). I’d recommend sticking to the Trelis/Cubit path for now if at all possible, but I’d be happy to help with the STL option if that’s your only way forward. As @paulromano mentioned, we’re looking into open source options for this. Specifically, there are efforts underway toward adding these imprint and merge features to OpenCascade.

It’s worth mentioning that Cubit is free for US academic institutions, so you may be able to apply for a license depending on your place of work as well.

Thanks to your reply. I feel very sorry that I cannot enjoy the free Cubit for I am a student in China.
I have send a email to the office of Trelis. They tell me a student may have a 50% discount which helps me a lot.
What’s more, I saw dagmc and Trelis can cooperation on windows,but

it is unstable. I didn’t find how to install HDF5 and MOAB. **May I got an specification of how to install HDF5,MOAB,and dagmc in windows?**This may helps a lot . For I haved tried to install dagmc for a week because when I try to install MOAB, it reminds me lack of NetCDF, After I have installed NetCDF, the MOAB still tells me lack of NetCDF,it takes me a lot time to repair it. but finally without the NetCDF I can still install the dagmc.
So maybe if you edit the dagmc instruction,could you add the MOAB didn’t need the NetCDF?
The last but the most important, I want to install tarball in my virtual machine(Ubuntu), but it report wrong, I can’t find how to solve it . What’s more I need to say, I didn’t find a file named ‘dagmc’ under the ‘plugins’, so I mkdir a file ‘dagmc’ myself.
Thank you very much , these problems troubled me a lot .

Installing the full stack of software necessary for this workflow can certainly be a pain. I don’t have any advice to offer here as I’m not a seasoned used of these packages. If you believe the installation instructions of these other packages is incomplete/wrong, I would encourage you to report it to the project maintainers. And if you run into OpenMC-specific problems, do let us know and we’ll do our best to assist.

Dear paulromano
thank you very much for your help .luckily , I understand how to install dagmc into Trelis. It is a little difficult for beginners of Linux, I read the of the tarball, it says link some lib file to some places, but we need to change the in the picture I will show how to modify it .

For I can just upload a picture , I put them together. Thank you again.

Dear Pshriwise
@pshriwise hello ,These days I found you upload a file named “trelis17.1_ubuntu18.04.tar.gz” on the website “”,and I found after I run the command “(sudo) ./” ,the Trelis17.1 can’t open ,I wonder if you meet the same question?
One thing to note , I use vmmare virtual machine.
Thank you very much,
I am waiting for your reply.

Hi Jiaylee,

Sorry for the delayed reply. I just now saw this message.

Since your post I uploaded an improved version of the plugin at the same location. To install it you simply need to unpack the plugin from the location /opt/Trelis-17.1/. I’d recommend re-installing Trelis before attempting the install of the plugin again.

Thank you for trying out DAGMC and let me know if you run into any issues!

Best regards,


I stumbled across this thread - wanted to drop a note that we now have a free non-commercial use license of Coreform Cubit that is available worldwide; export is limited to 50,000 elements. You can get it here: Free meshing software - Coreform Cubit Learn - Free non-commercial-use license