Add documentation for slab benchmark multiphysics problem. #99

meltawila · 2025-08-06T23:19:43Z

Closes #98

moosebuild · 2025-08-07T17:31:07Z

Job Documentation, step Sync to remote on 6c91500 wanted to post the following:

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moosebuild · 2025-08-07T17:36:07Z

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meltawila · 2025-08-07T19:54:51Z

@simopier would you activate the tests please?

simopier

This looks great overall!
However, I would recommend adding a test to run a very small version of this as part of the testing suite to make sure we maintain this capability available to users.

simopier · 2025-08-08T17:10:46Z

doc/content/bib/references.bib

+  organization = {ANS},
+  year         = {2022},
+  month        = {07},
+  booktitle = {Proceedings of  PHYSOR},


Suggested change

booktitle = {Proceedings of PHYSOR},

booktitle = {Proceedings of PHYSOR},

Added in my commit

simopier · 2025-08-08T17:12:45Z

doc/content/verification_validation_examples/slab_benchmark/model/make_openmc_model_dagmc.py

+T0 = 293
+Tmax = 393
+Tmin = 293
+L0 = 100
+L = 106.47


Suggested change

T0 = 293

Tmax = 393

Tmin = 293

L0 = 100

L = 106.47

T0 = 293 # K

Tmax = 393 # K

Tmin = 293 # K

L0 = 100 # cm

L = 106.47 # cm

Added in my commit

doc/content/verification_validation_examples/slab_benchmark/model/make_openmc_model_dagmc.py

doc/content/verification_validation_examples/slab_benchmark/model/openmc.i

simopier · 2025-08-08T17:32:19Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+
+## Results
+
+We see the heating result in [fig:heatingsol] compared against the analytic solution, as well as flux and temperature solutions in [fig:fluxsol] and [fig:tempsol]. Figures are only included for P=1.0E22 `[eV/s]` and on a fine mesh where the number of OpenMC and mesh elements is $N = 100$, since all results have a similar shape. Both the heating and flux tally everywhere agrees with the analytic solution within 3σ.


Suggested change

We see the heating result in [fig:heatingsol] compared against the analytic solution, as well as flux and temperature solutions in [fig:fluxsol] and [fig:tempsol]. Figures are only included for P=1.0E22 `[eV/s]` and on a fine mesh where the number of OpenMC and mesh elements is $N = 100$, since all results have a similar shape. Both the heating and flux tally everywhere agrees with the analytic solution within 3σ.

We see the heating result in [fig:heatingsol] compared against the analytic solution, as well as flux and temperature solutions in [fig:fluxsol] and [fig:tempsol]. Figures are only included for $P=1.0 \times 10^{22}$ eV/s and on a fine mesh where the number of OpenMC and mesh elements is $N = 100$, since all results have a similar shape. Both the heating and flux tally everywhere agrees with the analytic solution within 3$\sigma$.

simopier · 2025-08-08T17:32:48Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+  caption=Temperature result from MOOSE for N = 100 mesh elements compared against the analytic solution.
+  style=display:block;margin-left:auto;margin-right:auto;width:40%;
+
+Table [tab:results] shows results convergence with mesh refinement.


Suggested change

Table [tab:results] shows results convergence with mesh refinement.

[tab:results] shows results convergence with mesh refinement.

You shouldn't need Table here.

simopier · 2025-08-08T17:33:06Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+Table [tab:results] shows results convergence with mesh refinement.
+
+!table id=tab:results caption=Results and corresponding errors with different mesh sizes [!citep](eltawila2025).
+| **Resolution        | **Heated length `[cm]` | **Error `[μm]` | **$k_{\text{eff}}$** | **Error `[pcm]` |


Same comment about ** and `

simopier · 2025-08-08T17:33:41Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+| **Resolution        | **Heated length `[cm]` | **Error `[μm]` | **$k_{\text{eff}}$** | **Error `[pcm]` |
+| :- | :- | :- | :- | :- |
+| **Analytic solution | 106.47                 | --             | 0.29557              | --              |
+| **5                 | 106.3298               | -1402          | 0.29608 ± 0.00001    | 51 ± 1          |


Once the documentation builds, I'll need to check that the plus/minus signs work in markdown.

simopier · 2025-08-08T17:33:51Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+| **100               | 106.4745               | 45             | 0.29549 ± 0.00001    | -8 ± 1          |
+| **200               | 106.4748               | 48             | 0.29556 ± 0.00001    | -1 ± 1          |
+
+In [fig:fluxconv] and [fig:tempconv] convergence of flux and temperature relative L$^2$ norms, defined as


Suggested change

In [fig:fluxconv] and [fig:tempconv] convergence of flux and temperature relative L$^2$ norms, defined as

In [fig:fluxconv] and [fig:tempconv], convergence of flux and temperature relative L$^2$ norms, defined as

moosebuild · 2025-12-17T21:33:16Z

Job Build test summary, step Build test summary on 6c91500 wanted to post the following:

Test summary

Compared against 09a0610 in job civet.inl.gov/job/3460799.

Added tests

Test	Time (s)	Memory (MB)
`test:neutronics/moving_mesh.mesh_tally`	SKIP	0.00
`test:neutronics/moving_mesh.cell_tally`	SKIP	0.00

simopier

Thank you @meltawila!

Some additional comments on the new commits.
Things are moving in the right directlion.

By the way, for future rounds and PRs, it makes it easier over rounds of reviews if you incorporate the suggestions directly in the Files changed tab on the PR page. It incorporates the exact suggestion and then resolves the comment.

simopier · 2025-12-19T05:46:31Z

doc/content/bib/articles_using_salamander.bib


 @article{eltawila2025,
    title = {Thermomechanics Coupling to Monte Carlo Particle Transport on Unstructured Mesh Geometries},
+    journal = {SSRN Preprint},


To be updated

simopier · 2025-12-19T05:51:19Z

doc/content/verification_validation_examples/slab_benchmark/model/openmc.i

+# Cardinal input file for slab benchmark OpenMC model to couple with thermomechanics
+
+P = 1.0e22 # eV/s
+eV_to_J = 1.602e-19 # J/eV


Suggested change

eV_to_J = 1.602e-19 # J/eV

eV_to_J = 1.602176634e-19 # J/eV

This is what I meant by Use the value from PhysicalConstants.h instead.

doc/content/verification_validation_examples/slab_benchmark/model/openmc.i

simopier · 2025-12-19T05:52:15Z

doc/content/verification_validation_examples/slab_benchmark/model/openmc.i

+  [temp]
+    type = FunctionIC
+    variable = temp
+    function = 293


missed suggestion.

simopier · 2025-12-19T05:53:30Z

doc/content/verification_validation_examples/slab_benchmark/model/solid.i

+q = 1e8 # eV
+k0= 1.25e19 # eV/(s-cm-K^2) k(T) = k0 T(x)
+phi0 = 2.5e14 # 1/s-cm^2 (flux at the origin)
+eV_to_J = 1.602e-19 # J/eV


Suggested change

eV_to_J = 1.602e-19 # J/eV

eV_to_J = 1.602176634e-19 # J/eV

simopier · 2025-12-19T10:29:40Z

test/tests/neutronics/moving_mesh/cell_tally.i

@@ -0,0 +1,132 @@
+[GlobalParams]


Add a comment at the top of the input file, just like I requested for the others.

simopier · 2025-12-19T10:30:31Z

test/tests/neutronics/moving_mesh/mesh_tally.i

@@ -0,0 +1,133 @@
+[GlobalParams]


Add a comment at the top of the input to describe what it does.

simopier · 2025-12-19T10:32:18Z

test/tests/neutronics/moving_mesh/mesh_tally.i

@@ -0,0 +1,133 @@
+[GlobalParams]


It seems like this input file has a lot of similarities with the call_tally.i input file. Do you think it would make sense to generate a base input file and utilize the !include capabilities to reduce duplication?

simopier · 2025-12-19T10:35:57Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

 \end{equation}

-The example set of model parameter values shown in [tab:params] are the suggested benchmark parameters [!citep](griesheimer2022analytical), resulting in $k_\text{eff} = 0.29557$ and a heated slab length of $L = 106.47$ cm with $P = 1.0\times10^{22}$ eV/s.
+The example set of model parameter values shown in [tab:params] are the suggested benchmark parameters [!citep](griesheimer2022analytical), resulting in $k_\text{eff} = 0.29557$ and a heated slab length of $L = 106.47$ `cm` with $P = 1.0\times10^{22}$ `eV/s`.


General comment: I do not think you need the "`" signs around units. We usually do not use them in papers and in the rest of the documentation. For consistency, I recommend removing them.

simopier

Some more geenral comments on the tests and documentation now that it builds.
Thank you!

simopier · 2025-12-19T10:55:32Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+
+This verification problem presents capabilities to couple neutron transport with thermal conduction and material expansion. The analytic benchmark slab problem [!citep](griesheimer2022analytical) describes a slab where S$_2$ neutron transport is coupled with thermal conduction, convective boundary conditions, Doppler-broadened cross sections, and nonlinear thermal expansion effects along the heated slab. The benchmark provides the analytic solutions for steady-state temperature, neutron flux, heating, multiplication factor, and the heated slab length.
+
+While the restriction to S$_2$ neutron transport would be considered overly simplistic for most radiation transport  simulations, the objective here is to verify thermomechanical-OpenMC coupling using analytic solutions for three coupled solution fields (Displacements, temperature, and flux). Simplifications of each individual physics included in this model are not imposed by inherent limitations of the moving-mesh capabilities and only aim to allow the study on the interactions between multiphysics with an analytic solution.


Suggested change

While the restriction to S$_2$ neutron transport would be considered overly simplistic for most radiation transport simulations, the objective here is to verify thermomechanical-OpenMC coupling using analytic solutions for three coupled solution fields (Displacements, temperature, and flux). Simplifications of each individual physics included in this model are not imposed by inherent limitations of the moving-mesh capabilities and only aim to allow the study on the interactions between multiphysics with an analytic solution.

While the restriction to S$_2$ neutron transport would be considered overly simplistic for most radiation transport simulations, the objective here is to verify thermomechanical-OpenMC coupling using analytic solutions for three coupled solution fields (displacements, temperature, and flux). Simplifications of each individual physics included in this model are not imposed by inherent limitations of the moving-mesh capabilities and only aim to allow the study on the interactions between multiphysics with an analytic solution.

simopier · 2025-12-19T10:56:52Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+
+\begin{equation}
+  \label{eqn:rho_t}
+  \rho(x) = \rho_0\sqrt{\frac{T_0}{T(x)}}


Suggested change

\rho(x) = \rho_0\sqrt{\frac{T_0}{T(x)}}

\rho(x) = \rho_0\sqrt{\frac{T_0}{T(x)}}.

simopier · 2025-12-19T10:57:55Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+
+## Analytic solutions
+
+The reader is referred to the original benchmark publication [!citep](griesheimer2022analytical) for full details on the derivation of these solutions. Here we present the final formulas that we use later for comparison with our models.


Suggested change

The reader is referred to the original benchmark publication [!citep](griesheimer2022analytical) for full details on the derivation of these solutions. Here we present the final formulas that we use later for comparison with our models.

The reader is referred to the original benchmark publication [!citep](griesheimer2022analytical) and the updates made in [!citep](eltawila2025) for full details on the derivation of these solutions. Here we present the final formulas that we use later for comparison with our models.

simopier · 2025-12-19T11:01:50Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+
+The example set of model parameter values shown in [tab:params] are the suggested benchmark parameters [!citep](griesheimer2022analytical), resulting in $k_\text{eff} = 0.29557$ and a heated slab length of $L = 106.47$ `cm` with $P = 1.0\times10^{22}$ `eV/s`.
+
+!table id=tab:params caption=Example set of model parameters with two different power scenarios [!citep](griesheimer2022analytical).


You describe two power scenarios here, but you only list one in the table. Make sure to be consistent.

simopier · 2025-12-19T11:02:48Z

doc/content/verification_validation_examples/slab_benchmark/slab_benchmark.md

+This model is using S$_2$ neutron transport to compare with the 1D Analytic benchmark. To replicate
+the results, you have build your application with [this](https://github.com/meltawila/openmc_S2transport) patch of OpenMC.
+
+Cardinal is used to couple OpenMC with MOOSE via Picard iteration. OpenMC tallies neutron flux, heating, and the multiplication factor. A conceptual depiction of the meshes used as well as the data transfers that occur on each Picard iteration is shown in [fig:schematic]. Three different meshes/geometries are involved. The thermomechanics mesh is a simple 1D mesh of $N$ EDGE2 elements; the thermomechanical physics do not require higher dimensional (e.g. 2D or 3D) meshes for this problem. The OpenMC geometry is represented using DAGMC, where cells are bounded by a triangulated surface (TRI3 elements). To facilitate data transfers between OpenMC and MOOSE thermomechanics, there is also an intermediate volumetric data transfer mesh composed of TET4 elements; no physics solves happen on this intermediate mesh. [fig:schematic] highlights one element (for MOOSE and the Cardinal intermediate data transfer mesh) and one OpenMC cell each in blue, with adjacent portions of the geometry shown in gray for context.


Suggested change

Cardinal is used to couple OpenMC with MOOSE via Picard iteration. OpenMC tallies neutron flux, heating, and the multiplication factor. A conceptual depiction of the meshes used as well as the data transfers that occur on each Picard iteration is shown in [fig:schematic]. Three different meshes/geometries are involved. The thermomechanics mesh is a simple 1D mesh of $N$ EDGE2 elements; the thermomechanical physics do not require higher dimensional (e.g. 2D or 3D) meshes for this problem. The OpenMC geometry is represented using DAGMC, where cells are bounded by a triangulated surface (TRI3 elements). To facilitate data transfers between OpenMC and MOOSE thermomechanics, there is also an intermediate volumetric data transfer mesh composed of TET4 elements; no physics solves happen on this intermediate mesh. [fig:schematic] highlights one element (for MOOSE and the Cardinal intermediate data transfer mesh) and one OpenMC cell each in blue, with adjacent portions of the geometry shown in gray for context.

Cardinal is used to couple OpenMC with MOOSE via Picard iteration. OpenMC tallies neutron flux, heating, and the multiplication factor. A conceptual depiction of the meshes used as well as the data transfers that occur on each Picard iteration is shown in [fig:schematic]. Three different meshes/geometries are involved. The thermomechanics mesh is a simple 1D mesh of $N$ EDGE2 elements; the thermomechanical physics do not require higher dimensional (e.g., 2D or 3D) meshes for this problem. The OpenMC geometry is represented using DAGMC, where cells are bounded by a triangulated surface (TRI3 elements). To facilitate data transfers between OpenMC and MOOSE thermomechanics, there is also an intermediate volumetric data transfer mesh composed of TET4 elements; no physics solves happen on this intermediate mesh. [fig:schematic] highlights one element (for MOOSE and the Cardinal intermediate data transfer mesh) and one OpenMC cell each in blue, with adjacent portions of the geometry shown in gray for context.

simopier · 2025-12-19T11:20:44Z

test/tests/neutronics/moving_mesh/tests

The tests here do not reprocude the results from the paper, and are testing slightly other things using other input files.
I therefore have several reauests:

could you please add a section in the documentation to explain these tests and describe the input files being used here?

I'm not a fan of the fact that the input files relevant to the paper are not tested and will therefore likely get out of date as SALAMANDER/CARDINAL/OpenMC/MOOSE continue to evolve. If we can't reprocude the paper results with the regular build, is it not possible to create a test reciepe to use the OpenMC patch you need for this? At the very least, you should have all the input files go through a syntax check in one of the tests, or run for a short amount of time just to make sure they at least run. This should all be detailed a bit on the documentation page.

simopier · 2026-01-07T21:58:16Z

Do you need anything to finalize this, @meltawila?

meltawila added 2 commits August 6, 2025 17:17

Adding slab benchmark docs (idaholab#98)

1c56652

formatting and adding more docs

5fed070

simopier self-assigned this Aug 7, 2025

.bib changes

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simopier requested changes Aug 8, 2025

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meltawila and others added 3 commits December 2, 2025 15:11

update docs and address review comments

61cb706

Merge branch 'devel' into slab_benchmark

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adding tests

6c91500

simopier requested changes Dec 19, 2025

View reviewed changes

	booktitle = {Proceedings of PHYSOR},
	booktitle = {Proceedings of PHYSOR},


		## Results

		We see the heating result in [fig:heatingsol] compared against the analytic solution, as well as flux and temperature solutions in [fig:fluxsol] and [fig:tempsol]. Figures are only included for P=1.0E22 `[eV/s]` and on a fine mesh where the number of OpenMC and mesh elements is $N = 100$, since all results have a similar shape. Both the heating and flux tally everywhere agrees with the analytic solution within 3σ.

	Table [tab:results] shows results convergence with mesh refinement.
	[tab:results] shows results convergence with mesh refinement.

	In [fig:fluxconv] and [fig:tempconv] convergence of flux and temperature relative L$^2$ norms, defined as
	In [fig:fluxconv] and [fig:tempconv], convergence of flux and temperature relative L$^2$ norms, defined as


		This verification problem presents capabilities to couple neutron transport with thermal conduction and material expansion. The analytic benchmark slab problem [!citep](griesheimer2022analytical) describes a slab where S$_2$ neutron transport is coupled with thermal conduction, convective boundary conditions, Doppler-broadened cross sections, and nonlinear thermal expansion effects along the heated slab. The benchmark provides the analytic solutions for steady-state temperature, neutron flux, heating, multiplication factor, and the heated slab length.

		While the restriction to S$_2$ neutron transport would be considered overly simplistic for most radiation transport simulations, the objective here is to verify thermomechanical-OpenMC coupling using analytic solutions for three coupled solution fields (Displacements, temperature, and flux). Simplifications of each individual physics included in this model are not imposed by inherent limitations of the moving-mesh capabilities and only aim to allow the study on the interactions between multiphysics with an analytic solution.

	\rho(x) = \rho_0\sqrt{\frac{T_0}{T(x)}}
	\rho(x) = \rho_0\sqrt{\frac{T_0}{T(x)}}.


		## Analytic solutions

		The reader is referred to the original benchmark publication [!citep](griesheimer2022analytical) for full details on the derivation of these solutions. Here we present the final formulas that we use later for comparison with our models.


		The example set of model parameter values shown in [tab:params] are the suggested benchmark parameters [!citep](griesheimer2022analytical), resulting in $k_\text{eff} = 0.29557$ and a heated slab length of $L = 106.47$ `cm` with $P = 1.0\times10^{22}$ `eV/s`.

		!table id=tab:params caption=Example set of model parameters with two different power scenarios [!citep](griesheimer2022analytical).

Add documentation for slab benchmark multiphysics problem. #99

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moosebuild commented Dec 17, 2025

Test summary

Added tests

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meltawila commented Aug 6, 2025 •

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