Fluid temperature stuck at initial conditions when transferring wall temperature to solid from THM

[MattMavis]

Hi,

I’m just looking for some help with adapting the temperature and volume tutorial example for use in my geometry. Currently it seems like the transfers between thm -> openmc -> solid isn’t working for thm wall temp. It seems it is stuck at the defined initial condition instead of taking the newly transfer the values.

[aprilnovak]

Hi @MattMavis, can you share more information about the model (perhaps input files, if possible)? Another possible culprit could be Paraview usage when viewing the output files -- this discussion might be relevant as the symptom sounds similar to your case: #1095

[MattMavis]

Hi April,

Unfortunately my work network won’t let me upload files, but it won’t be necessary in this case as I believe I solved it.
After posting here I had the nagging feeling it was something to do with the nearest node mapping of the THM wall temperature data not being performed as expected.

That was when I noticed that the aux variable thm_temp_wall was assigned only to block=‘101’ which is the coolant channel mesh block.

By removing this the block assignment, it now works fine and the wall temperature is now assigned to the solid block boundaries correctly.

As to why this happens, I can only assume that because the boundary that the thm wall temp is assigned to be written onto is defined on the solid mesh not the channel/fluid mesh, and by limiting the variable to only see the channel block it does not see the correct mesh to write onto.

[aprilnovak]

Yes, you have to be careful with transferring data that the variables actually exist on the subdomain/sideset/etc. where they will be queried/written to on the different meshes communicating in the transfer.

For this particular tutorial, thm_wall_temp is a variable that exists in the OpenMC main app; its only purpose is to serve as an intermediate point for the THM wall temperature from the thm.i file to get into the solid.i file. In the OpenMC input file, even though the variable represents a temperature on the fluid-solid boundary, it doesn't need to "live" there because ultimately that intermediate variable will get passed to the fluid-solid boundary in the solid.i where it then actually participates in the boundary condition. This is all a bit circuitous because at the time the tutorial was written, two sub-apps couldn't pass data between one another.

Depending on what you modified in your adaptation of the tutorial, perhaps the block/side restriction was changed and changed the behavior.