AMR-Compat SurfaceIntegrals

[DanielDoehring]

This fixes https://github.com/trixi-framework/Trixi.jl/issues/1955 by re-computing the boundary indices every time the surface integral is computed.

As the boundary indices need to be specified as a Tuple and no longer simply a Symbol or Vector of Symbols, this is breaking.

[github-actions[bot]]

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.16%. Comparing base (def208b) to head (cdd1bc7). Report is 4 commits behind head on main.

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[DanielDoehring]

Thanks for tackling this. How urgent is the fix for you? I'm asking since this is a hotfix with a breaking change. An alternative would be to implement a notification by the AMR callback as mentioned in #215. Thus, we may discuss whether this could be a more general approach that helps us in the long run

I plan to show/use this for the JuliaCon talk (this is also where I realized that this is buggy).

I absolutely agree that #215 makes a hell lot of sense, but this also seems to me like a very-long range project. Until then, I suggest that we get the callback working also with AMR.

[ranocha]

Ok. How much overhead do we get by this for non-AMR cases?

[DanielDoehring]

How much overhead do we get by this for non-AMR cases?

I added some timings:

 analyze solution                    27    175ms    1.2%  6.48ms    564KiB    5.9%  20.9KiB
   ~analyze solution~                27    174ms    1.2%  6.44ms    361KiB    3.8%  13.4KiB
   AnalysisSurfaceIntegral          108    998μs    0.0%  9.24μs    203KiB    2.1%  1.88KiB
     ~AnalysisSurfaceIntegral~      108    851μs    0.0%  7.88μs      752B    0.0%    6.96B
     inidices                       108    147μs    0.0%  1.36μs    202KiB    2.1%  1.88KiB

for this elixir: https://github.com/trixi-framework/Trixi.jl/blob/main/examples/p4est_2d_dgsem/elixir_navierstokes_NACA0012airfoil_mach08.jl So there are some allocations due to the reconstruction of the indices vector.

Note that the callback gets in this case called every 10th timestep, much more than in an actual case. But this allowed me to reduce the total runtime and the analysis interval.

[Arpit-Babbar]

I see that this PR is mentioned in v0.8. Does it mean that it will be merged eventually? There is no urgency from my side, but it will be good to know. If this PR is going to be merged, we can make this nearly final (i.e., ready to merge whenever v0.8 is released) and rebase https://github.com/trixi-framework/Trixi.jl/pull/1920 on top of this.

[ranocha]

Yes, I think it would be good to merge this somewhat soon and release v0.8. What's your take on this, @DanielDoehring?

[DanielDoehring]

I added this to v0.8 as this is a breaking change, which we typically handle by increasing the first version decimal. From my side this is good to go, so you are kindly invited to review this (again). :)

[ranocha]

Thanks!

@Arpit-Babbar Any suggestions from your side to improve this PR? Otherwise, I would like to proceed as you suggested above

If this PR is going to be merged, we can make this nearly final (i.e., ready to merge whenever v0.8 is released) and rebase #1920 on top of this.

[ranocha]

@Arpit-Babbar Are there further breaking changes that you need for https://github.com/trixi-framework/Trixi.jl/pull/1920?

[ranocha]

@sloede How's your review going? Do you have a rough estimate when you will have some time for it?

[sloede]

As the boundary indices need to be specified as a Tuple and no longer simply a Symbol or Vector of Symbols, this is breaking.

Why again is this change needed and couldn't remain a Vector of symbols?

[DanielDoehring]

I wonder, however, whether this is really a breaking change. From what I can see, this is really a bugfix, since the surface integral computation was already used for AMR simulations but just produced the wrong output. I thus think this shouldn't require a minor version bump, but only a patch release.

The reason why this is breaking is that the boundary symbols have now to be supplied as a NTuple, not just a Symbol or a Vector of Symbols. Thus, even in the non-AMR case the user interface changes.