Using CAD/DAGMC geometry with FLUKA 4.5-1 - FluDAG no longer works

Geometry and Materials
1

Versions

Please provide the used software versions.

FLUKA:4.5-1
Flair:

Description

Dear FLUKA experts,

I’m trying to run FLUKA simulations with complex CAD geometry (STEP files), and I need help finding the right approach. What I have:

FLUKA 4-5.1
CAD geometry in STEP format
The same geometry already works in OpenMC via DAGMC (H5M file)
DAGMC/MOAB v5.6.0 installed

What I tried:

FluDAG — fails to compile because libflukahp.a no longer exists in FLUKA 4.5-1
FLUKA Voxel geometry — only creates bounding boxes per material, not individual voxels
FLUKA Unstructured Mesh (UMESH) — gmsh/netgen fail to generate volume mesh from our STEP files due to non-watertight surfaces

My question:
What is the recommended workflow in 2024/2025 to use complex CAD geometry in FLUKA 4.5-1? Is there an updated alternative to FluDAG that works with FLUKA 4.5? Or is there a way to use our existing DAGMC H5M file directly?

Thank you!

Alejandra

Input files

Please upload all relevant files. (FLUKA input file, Flair project file, user routines, and data files)

2

It’s lib/libfluka.a

4

Thank you for the response. We have libfluka.a at /usr/local/fluka/lib/libfluka.a.
Could you please clarify: should we simply replace libflukahp.a with libfluka.a in the FluDAG CMakeLists.txt? Or is there a newer/updated version of FluDAG that officially supports FLUKA 4.5?

5

Dear Alejandra,

There are a few additional FLUKA libraries that have to be linked.

I successfully compiled FluDAG and ran the tests with this modified version of FindFluka.cmake

find_path(FLUKA_LIBDIR
  NAMES libfluka.a
  HINTS ${FLUKA_DIR}
  PATHS ENV FLUKA_DIR
  NO_DEFAULT_PATH
)

if (NOT FLUKA_LIBDIR)
  message(FATAL_ERROR "Could not find Fluka")
endif ()

set(FLUKA_LIBRARIES
  ${FLUKA_LIBDIR}/libfluka.a
  ${FLUKA_LIBDIR}/libgeometry.a
  ${FLUKA_LIBDIR}/libdata.a
  ${FLUKA_LIBDIR}/libmath.a
  ${FLUKA_LIBDIR}/libtool.a
  gfortran
  z
  pthread
)

message(STATUS "FLUKA_LIBRARIES: ${FLUKA_LIBRARIES}")
message(STATUS "Found Fluka")

However, we’d recommend using the UMESH feature. Sometimes, meshing tools (tetgen/gmsh etc.) create non-watertight geometry due to too coarse tessellation. If you could send me your STEP files (privately), I can check it for issues.

FluDAG might have worked for you because, with certain workflows, it calls the make_watertight command, which patches geometry issues behind the scenes.

Best regards,
Volodymyr

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