[jnagy]

Comments and questions are welcomed on the article Ulrich et al., Development of an OpenFOAM® Solver to Investigate the Dynamic Absorption and Desorption Processes in Metal Hydrides, OpenFOAM Journal, 14 March 2025, https://doi.org/10.51560/ofj.v5.110.

[dlahaye]

Greetings,

The link provided does not point the paper.

Possibly I am overlooking something?

Thanks.

[jnagy]

Dear Domenico,

you are correct, however now it should work. Thank you for your valuable input.

[hef]

The twoRegionHydrideFoam code described in the paper is quite neat, I think. However, I have a question I can't figure out from the paper:

In the file constant/metalHydrideSettings, delta_wall is defined so it can be used in other parts of the code, typically when setting boundary conditions for temperature. I don't understand why delta_wall is not simply equal to wallThickness? Instead, the template uses a scaling factor with a rather small "default" value of 1e-3. Why is this needed, i.e., why shouldn't I use the wall thickness directly as delta_wall?

[chriz11]

Originally Posted by hef

The twoRegionHydrideFoam code described in the paper is quite neat, I think. However, I have a question I can't figure out from the paper:

In the file constant/metalHydrideSettings, delta_wall is defined so it can be used in other parts of the code, typically when setting boundary conditions for temperature. I don't understand why delta_wall is not simply equal to wallThickness? Instead, the template uses a scaling factor with a rather small "default" value of 1e-3. Why is this needed, i.e., why shouldn't I use the wall thickness directly as delta_wall?

Hey, sorry for the late response. We use the 1e-3 in metalHydrideSettings as the wallThickness is read from the blockMeshDict where it is declared in mm. If you want to, you can change this and ignore the 1e-3 .

Best regards,
Christoph

[hef]

Originally Posted by chriz11

Hey, sorry for the late response. We use the 1e-3 in metalHydrideSettings as the wallThickness is read from the blockMeshDict where it is declared in mm. If you want to, you can change this and ignore the 1e-3 .

Best regards,
Christoph

Ah, perhaps I should have thought of that. Thank you very much for your answer!

I'm trying to modify twoRegionHydrideFoam so that a constant "filling rate" can be specified. This will be implemented by dynamically modifying the inlet pressure based on the volume-averaged absorption rate in the metal hydride. During my implementation, I came across two minor issues with the code, in case you're interested:

1) When trying to use OpenFOAM's volFieldValue function object, the solver crashes. I think this has something to do with the way the mesh regions are set up, but I'm not certain. (Let me know if you want me to send you the error output.)

2) The density field (rhoGas) on the inlet is not properly updated; for example, when using transient boundary conditions for p and rho, the initial BC value for rhoGas is still retained for the entire simulation. I think this is because rhoGas is explicitly calculated from the ideal-gas law in the code (rhoGasEqn_hydrogen.H) instead of being solved iteratively (which is where the BCs are typically incorporated). So far, I've fixed this by explicitly calculating the boundary field for rho in the same way as the interior field (i.e., from the ideal-gas law), but a more general solution could obviously be implemented.

These are only small problems, and I am very grateful for your publication of this code. Thank you for your excellent work.

[chriz11]

Hey,

Regarding 1, please feel free to post your error code. Perhaps we can identify the problem.

Regarding point 2: for our purposes, the released code was sufficient, but as you mentioned, a more general solution could be implemented. It's good to hear that you found a working solution, though.


Best regards,
Christoph

[solon1210]

Hello,

In the parameter studies (section 5.2) it is mentioned that "The findings are consistent with those reported in ...", however, I couldn't find anything that shows this comparison. Was it a qualitative consistency, or were the results explicitly compared to experimental data, for example?

Thanks

[chriz11]

Hey!

We found qualitative consistency. We tried to be precise by citing the relevant source after each statement.

[solon1210]

Hello,

Thanks for the clarification!