Document heat transfer kernels.

[aprilnovak]

Closes #29645

Reason

I would like to teach a class using MOOSE; improved documentation will help students.

Summary/Justification of Changes

• The phrase "diffusivity" specifically means the ratio of the property on the Laplacian term relative to that on the time term. It is not a synonym for diffusion coefficient. Relevant documentation corrected.
• It is a common misconception that rho * Cp are only outside the time derivative if they are constant. They should always be outside (this can be shown from a rigorous derivation of the heat equation starting from conservation of total energy (kinetic + internal), the entropy equation, and thermodynamic identities. Relevant documentation corrected.
• I think the statement on the HeatConductionTimeDerivative page about not considering on-diagonal Jacobian contributions from Cp and rho is just wrong -- the source code shows it is there? Relevant documentation corrected.
• I tried to use a consistent approach to have every AD page just reference the non-AD page to avoid duplicating text.

Discussion for additional ideas not yet in this PR:

• I would like to propose deleting HeatCapacityConductionTimeDerivative. Looks like it's not used anywhere in the framework, not even tested.
• SpecificHeatConductionTimeDerivative looks like a better version of HeatConductionTimeDerivative because it uses the DerivativeMaterialInterface to get off-diagonal Jacobian terms. Would suggest making HeatConductionTimeDerivative internally equivalent to the former and then deprecating SpecificHeatConductionTimeDerivative to remove confusion.

[moosebuild]

Job Precheck, step Clang format on 5a012b4 wanted to post the following:

Your code requires style changes.

A patch was auto generated and copied here
You can directly apply the patch by running, in the top level of your repository:

curl -s https://mooseframework.inl.gov/docs/PRs/29646/clang_format/style.patch | git apply -v

Alternatively, with your repository up to date and in the top level of your repository:

git clang-format 1e17680adfcc2117439231c38b5bb9cb3a102636

[moosebuild]

Job Documentation, step Docs: sync website on 332ed8f wanted to post the following:

View the site here

This comment will be updated on new commits.

[moosebuild]

Job Coverage, step Generate coverage on 332ed8f wanted to post the following:

Framework coverage

Coverage did not change

Modules coverage

Heat transfer

	b45164	#29646 332ed8
	Total	Total	+/-	New
Rate	88.63%	88.63%	-	100.00%
Hits	4414	4414	-	4
Misses	566	566	-	0

Diff coverage report

Full coverage report

Full coverage reports

Reports

• framework
• chemical_reactions
• combined
• contact
• electromagnetics
• external_petsc_solver
• fluid_properties
• fsi
• functional_expansion_tools
• geochemistry
• heat_transfer
• level_set
• misc
• navier_stokes
• optimization
• peridynamics
• phase_field
• porous_flow
• ray_tracing
• rdg
• reactor
• richards
• scalar_transport
• solid_mechanics
• solid_properties
• stochastic_tools
• thermal_hydraulics
• xfem

This comment will be updated on new commits.

[aprilnovak]

I think the test failure is unrelated?

[aprilnovak]

I opted to remove any discussion about Jacobians -- it's not done uniformly across the documentation, and IMO if someone is concerned about Jacobian issues they should be using AD.

Other than the comment about AD vs. non-AD markdown files, I think I've addressed everything.

[moosebuild]

Job Coverage, step Verify coverage on 9c53c05 wanted to post the following:

The following coverage requirement(s) failed:

• Failed to generate chemical_reactions coverage rate (required: 92.0%)

[lindsayad]

woops I led you astray there for a bit

[lindsayad]

Looks like you still have some links to ADGenericConstantMaterial.md

[aprilnovak]

ack sorry, fixed it.

[lindsayad]

failure unrelated to documentation