How to load the Nemesis mesh group ?

[mangerij]

Say I have outputs from a single calculation

out_PTOfilm_e25_T298K_E0_E0.e.N.M

where N is number of total processors and M is the processor index. I want to load the group of these files as my mesh for a new calculation (same partitioning). Is this possible?

Along with file = out_PTOfilm_e25_T298K_E0_E0.e, I tried to add nemesis=true and skip_partition= true in the [Mesh] block and that does nothing.

I also checked the test/tests/mesh/nemesis_test.i test and I have the same syntax to load the files.

The weird thing is that the error message says that it sees the files but for example,

*** ERROR ***
Error opening ExodusII mesh file: /lcrc/project/Meso/projects/ferret/out_PTOfilm_e25_T298K_E0_E46.e.256.060

thanks
John

[PM-Hu]

Hi
I'm new to MOOSE, and also meet that error when I was intending to use the Exodus file generated by Trelis in Mesh block.
The chmod command may solve that error to change the ExodusII mesh file's [out_PTOfilm_e25_T298K_E0_E46.e.256.060] mode.

hope that helps you
Hu

[GiudGiud]

Is this solved?

[Traiwit]

im having hard time loading the variable data back to MOOSE via nemesis mesh

in exodus i usually do:

  [mesh_G01Hv1]
    type = FileMeshGenerator
    file = 'XXXX.e'
    allow_renumbering = false
    use_for_exodus_restart = true  ## for restart_mode
  []

then

[Variables]
  [porepressure_L1]
    type = MooseVariable
    order = FIRST
    family = LAGRANGE
    initial_from_file_var = porepressure_L1  ## for restart_mode
    initial_from_file_timestep = LATEST      ## for restart_mode   
  []
[]

but this wont work with nemesis

even if i do

  # file = '/home/moose/Downloads/LKABKIR2025081/2_RUN_MOOSE/R09HR01/outputNemesis/R11HR01/LKABKIR2025081_R11HR01_F004.e'
  # nemesis = true
  # skip_partitioning = true
  # use_for_exodus_restart = true 
  
  under [Mesh]

i will have problem with loading variable data and assigning data from PropertyReadFile

is there a way to work around?

SolutionUserObject - wont work as well, as it only takes .e

Regards,
Traiwit

[Traiwit]

or is there a way to convert nemesis back to single .e and i can restart from there?

[GiudGiud]

Hello

Exodus restart does not support nemesis I think

However I have a PR open to use nemesis for restarts via solution user objects if you want to try that out

[Traiwit]

i see, thank you @GiudGiud

I went with the harder route:

-> convert nemesis files into .e via external py script

-> then restart simulation with .e and back to nemesis output again

seems to work for now but painful

[GiudGiud]

Yeah that should work.
You just lose the distrivuted side of nemesis which the solutionUO technique should not (its the intent of that PR)