New AMR indicator IndicatorNodalFunction

[TJP-Karpowski]

Positional Indicator and Testcases

The PR adds a Positional Indicator which allows us to define a function rule(x,t) and use it to drive AMR.
As mentioned in #2880 this is targeted for testing purposes to create highly dynamic AMR grids to test refinement, unrefinement, and mortars, especially with MPI.
As an example, I have attached a video of the examples/p4est_2d_dgsem/elixir_navierstokes_lid_driven_cavity_amr_mortarTestcase.jl case showcasing the capability by pulsing the refinement zone with a sin function.

The testcases are envisioned to test MPI mortars for the hyperbolic parabolic system as mentioned in #2880 .

Open question

• Is the weighted average of the nodes a valid proxy for the element centers? It seemed reasonable to me.
• I did not add a 1D testcase for the IndicatorPositional as the use case is again for MPI treatments in 3D or 2D

@DanielDoehring, I hope this clarifies the feature's use case.

Disclaimer

LLMs have been used to aid in the PR, though sparingly.

Funding Statement

This work has been funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project Number 237267381 – TRR 150.

[github-actions]

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[DanielDoehring]

Thanks for getting this started! I added a first review, which is mostly about namings and the evaluation of the indicator at the cell center.

Furthermore, I am not sure if Positional is good naming, as this somewhat drops that you can also add time as an argument.

[codecov]

Codecov Report

❌ Patch coverage is 93.84615% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.07%. Comparing base (ce719f3) to head (7db5065).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/solvers/dgsem/indicators.jl	94.74%	1 Missing ⚠️
src/solvers/dgsem_tree/indicators_1d.jl	93.33%	1 Missing ⚠️
src/solvers/dgsem_tree/indicators_2d.jl	93.33%	1 Missing ⚠️
src/solvers/dgsem_tree/indicators_3d.jl	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2881      +/-   ##
==========================================
+ Coverage   96.76%   97.07%   +0.31%     
==========================================
  Files         610      611       +1     
  Lines       47500    47565      +65     
==========================================
+ Hits        45960    46171     +211     
+ Misses       1540     1394     -146     

Flag	Coverage Δ
unittests	97.07% <93.85%> (+0.31%)	⬆️

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[DanielDoehring]

Implementationwise, this is already looking very good to me! Now we only need to cover the code & set up tests.

[ranocha]

Thanks for your contribution!

[ranocha]

Thanks, this looks good to me.

[ranocha]

The CI failure seems to come from the recent SciML updates (OrdinaryDiffEq.jl and supporting ecosystem). Running the failing test locally passes with older versions of the SciML packages, but fails after updating them.

Xref SciML/OrdinaryDiffEq.jl#3331