Executable for MC: initialize background #6355

ffoucart · 2024-10-30T14:44:03Z

Proposed changes

Create base MC executable

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The code is documented and the documentation renders correctly. Run
make doc to generate the documentation locally into BUILD_DIR/docs/html.
Then open index.html.
The code follows the stylistic and code quality guidelines listed in the
code review guide.
The PR lists upgrade instructions and is labeled bugfix or
new feature if appropriate.

ffoucart · 2024-10-30T14:44:27Z

Work in progress -- first commit creates the background fluid and metric variables, EoS and neutrino table.

ffoucart · 2024-10-30T14:46:36Z

@nilsdeppe Not sure if we want one big PR for the MC code, or to commit partial work once we have something useful. I'm keeping the work we have done so far (slightly cleaned up for compatibility with other executables) here.

ffoucart · 2024-12-06T16:01:49Z

Rebased on develop to fix minor conflict with RunEventsAndTriggers (template change, option renamed)

ffoucart · 2024-12-23T15:17:43Z

Rebased to make dependent on #6424 . The first commit is now from that PR, the second commit creates the executable; the final part to make it work with input files is in #6403

ffoucart · 2025-01-24T18:48:15Z

Rebased on develop after merging #6424

kidder · 2025-01-24T18:44:29Z

src/Evolution/Executables/RadiationTransport/MonteCarlo/EvolveMonteCarlo.hpp

+  using initialization_actions = tmpl::list<
+      Initialization::Actions::InitializeItems<
+          Initialization::TimeStepping<EvolutionMetavars, TimeStepperBase>,
+          evolution::dg::Initialization::Domain<volume_dim>  //,


remove the comment at the end of the line

kidder · 2025-01-24T18:46:17Z

src/Evolution/Executables/RadiationTransport/MonteCarlo/EvolveMonteCarlo.hpp

+          Parallel::PhaseActions<
+              Parallel::Phase::Evolve,
+              tmpl::list<
+                  Actions::AdvanceTime,


comment why these actions are repeated and if you plan to change how this works in the future

Good catch.
This is because MC only occurs after a full step, not intermediate step, and I am using a RK3 time stepper. That's not a good reason of course. What I should have here is some way to loop over all intermediate time steps of the time stepper and for each step do (AdvanceTime, RunEvents). Is there a simple way to do that for a generic timestepper with arbitrary number of intermediate steps?
We could also require MC to use forward Euler when not coupled to the fluid/metric. As that's what the code is actually doing at the moment, regardless of the choice of timestepper in the input files.

Okay I discussed with @nilsdeppe and we think you should be able to use something like the Actions::Label that are used to switch between Dg actions and subcell actions. So you would surround the MC actions with two labels (e.g. BeginMonteCarlo and EndMonteCarlo). Then you can add an action immediately before the BeginMonteCarlo label similar to evolution::dg::subcell::Actions::SelectNumericalMethod that will test whether the time substep is 0 and choose which label to jump to. This then will be independent of the time stepper choice.

Thanks. I got it to work, but please look at the new Labels.hpp and TriggerMonteCarlo.hpp files as well as the action list to check that it is what you had in mind. These are the main changes in the new version of the PR (the other comments were fairly simple to take care of).

kidder · 2025-01-24T19:27:04Z

src/Evolution/Particles/MonteCarlo/Actions/InitializeMonteCarlo.hpp

+        [&box](const auto* const data_or_solution) {
+          static constexpr size_t dim = System::volume_dim;
+          const double initial_time = db::get<::Tags::Time>(box);
+          const size_t num_grid_points =


You've already retrieved this above, so just capture it in the lambda

kidder · 2025-01-24T19:28:34Z

src/Evolution/Particles/MonteCarlo/Actions/InitializeMonteCarlo.hpp

+      const Parallel::GlobalCache<Metavariables>& /*cache*/,
+      const ArrayIndex& /*array_index*/, ActionList /*meta*/,
+      const ParallelComponent* const /*meta*/) {
+    const size_t num_grid_points =


This assumes that Tags::ActiveGrid is ActiveGrid::Subcell. Instead check what the value is and either ERROR or update to handle correctly if it is ActiveGrid::Dg

kidder · 2025-01-24T19:29:03Z

src/Evolution/Particles/MonteCarlo/Actions/InitializeMonteCarlo.hpp

+        make_not_null(&box), std::move(all_packets));
+
+    const unsigned long seed =
+        std::random_device{}();  // static_cast<unsigned long>(time(NULL));


remove commented code

kidder · 2025-01-24T19:33:08Z

src/Evolution/Particles/MonteCarlo/Actions/TimeStepActions.hpp

@@ -131,14 +132,30 @@ struct TimeStepMutator {
    const DirectionalIdMap<Dim, std::optional<DataVector>>&
        cell_light_crossing_time_ghost = mortar_data.cell_light_crossing_time;

+    tnsr::iJJ<DataVector, 3, Frame::Inertial> d_inv_spatial_metric =


call the existing function in PointwiseFunctions/GeneralRelativity/DerivativeSpatialMetric.hpp

kidder · 2025-01-24T19:35:24Z

src/Evolution/Particles/MonteCarlo/GhostZoneCommunication.hpp

@@ -311,8 +321,8 @@ struct ReceiveDataForMcCommunication {
                const DataVector& received_data_direction =
                    received_data[directional_element_id]
                        .ghost_zone_hydro_variables;
-                REQUIRE(received_data[directional_element_id]
-                            .packets_entering_this_element == std::nullopt);
+                // REQUIRE(received_data[directional_element_id]


kidder · 2025-01-24T19:35:34Z

src/Evolution/Particles/MonteCarlo/GhostZoneCommunication.hpp

@@ -368,8 +378,8 @@ struct ReceiveDataForMcCommunication {
                        received_data[directional_element_id]
                            .packets_entering_this_element;
                // Temporary: currently no data for coupling to the fluid
-                REQUIRE(received_data[directional_element_id]
-                            .ghost_zone_hydro_variables.size() == 0);
+                // REQUIRE(received_data[directional_element_id]


kidder · 2025-01-24T19:36:54Z

src/Evolution/Particles/MonteCarlo/System.hpp

+  using spacetime_variables_tag =
+      ::Tags::Variables<gr::tags_for_hydro<volume_dim, DataVector>>;
+  using flux_spacetime_variables_tag = ::Tags::Variables<tmpl::list<>>;
+  // Hydro tags needed for background metric


why metric?

kidder

Looks good to me, you can squash

ffoucart · 2025-01-27T16:09:10Z

Thanks. Will wait for the tests to complete here, then work on rebasing the next PR against these changes.

ffoucart · 2025-01-28T01:39:16Z

Tests only failing due to Timeout in an unrelated test (I tried to rerun, but the same test failed twice)

ffoucart added the in progress Don't review, used for sharing code and getting feedback label Oct 30, 2024

ffoucart force-pushed the MCExecutable branch from b247bff to 3f49648 Compare November 1, 2024 18:04

ffoucart force-pushed the MCExecutable branch 2 times, most recently from 41053cd to f533cb9 Compare November 21, 2024 21:11

ffoucart removed the in progress Don't review, used for sharing code and getting feedback label Dec 5, 2024

ffoucart marked this pull request as ready for review December 5, 2024 14:30

ffoucart force-pushed the MCExecutable branch 3 times, most recently from 45d1b93 to 84ed5be Compare December 6, 2024 16:01

ffoucart force-pushed the MCExecutable branch 2 times, most recently from eb41b51 to 9a144ff Compare December 6, 2024 19:46

This was referenced Dec 10, 2024

Mc optically thick sphere #6402

Closed

Mc optically thick sphere #6403

Open

ffoucart force-pushed the MCExecutable branch from 6e7a392 to f600392 Compare December 23, 2024 15:16

ffoucart force-pushed the MCExecutable branch from f600392 to 1c22afe Compare January 24, 2025 18:47

kidder requested changes Jan 24, 2025

View reviewed changes

ffoucart force-pushed the MCExecutable branch from 715ddc1 to 4b0d356 Compare January 27, 2025 15:58

kidder reviewed Jan 27, 2025

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Base executable for MC

012bfaf

ffoucart force-pushed the MCExecutable branch from 4b0d356 to 012bfaf Compare January 27, 2025 16:08

kidder merged commit dfbc372 into sxs-collaboration:develop Jan 28, 2025
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Executable for MC: initialize background #6355

Executable for MC: initialize background #6355

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Executable for MC: initialize background #6355

Executable for MC: initialize background #6355

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ffoucart commented Oct 30, 2024

Proposed changes

Upgrade instructions

Code review checklist

ffoucart commented Oct 30, 2024

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ffoucart commented Jan 27, 2025

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ffoucart commented Dec 6, 2024 •

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