Issue Loading .bmesh File in FLUKA on macOS

Running and Runtime Errors
1

Versions

FLUKA: fluka4-5.1
Flair: flair-3.4-5.2 and flair-geoviewer-3.4-5.2
Operating system: macOS Sonoma 14.5 (Apple M2 Pro)
Compiler:

  • xcode-select --version: xcode-select version 2408
  • gcc --version: gcc (MacPorts gcc13 13.4.0_1+stdlib_flag) 13.4.0
  • python --version: Python 3.13.7

Description

I am currently experiencing an issue when running FLUKA with a .bmesh file on my laptop. When I attempt to run FLUKA with a .bmesh file, the program fails to load the file and produces the following error messages:

>e> ERROR: unknown file format

STOP Could not load umesh

STOP STOP: FLUKA ABORTED

Error loading umesh “../transition_1-26.bmesh”

Abort called from VXLINP reason Could not load umesh Run stopped!

STOP Could not load umesh

I noticed that when FLUKA runs, it creates subfolders (e.g., fluka_XXXX), but the .bmesh file is not copied into these subfolders. As a result, it appears that the file cannot be found or loaded.

To address this, I modified the .inp file so that it references the .bmesh file located one directory level above. This approach works correctly on our cluster computing system. However, the same setup does not work on my laptop.

Screenshot 2026-02-28 at 2.54.07 PM

I would greatly appreciate any guidance or suggestions you may have to help resolve this issue.

Thank you very much in advance for your time and assistance.

Best regards,
Jihee

3

Dear Jihee,

Could you please provide a minimal input with the mesh that you are trying to use (before and after conversion to .bmesh format)?

I noticed that when FLUKA runs, it creates subfolders (e.g., fluka_XXXX), but the .bmesh file is not copied into these subfolders. As a result, it appears that the file cannot be found or loaded.

It’s not an issue if you run your input in the same folder with mesh. Once you create a subfolder for runs, path to the file or symlink inside that folder is needed.
Example:

image

First input will run (without ../) and the second one will be terminated with the same error:

Abort called from VXLINP reason Could not load umesh Run stopped!

STOP Could not load umesh

It has a similar behaviour to SOURCEroutine when the beam distribution is read from a file.

Please try these suggestions first, and let me know.

Best regards,
Volodymyr