Bugfix to particle defragmentation #1185
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brryan
commented
Oct 5, 2024
| "Set empty indices prefix sum", 0, nmax_pool_ - num_active_ - 1, | ||
| KOKKOS_LAMBDA(const int nn, int &update, const bool &final) { | ||
| const int n = nn + num_active; | ||
| "Set empty indices prefix sum", num_active, nmax_pool_ - 1, |
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Not a change to behavior, this is just clearer IMO
brryan
commented
Oct 5, 2024
| if (final) scan_scratch_toread(n) = update; | ||
| if (final) { | ||
| scan_scratch_toread(n) = update; | ||
| empty_indices(n - num_active) = n; |
brryan
commented
Oct 5, 2024
| @@ -62,6 +62,11 @@ std::shared_ptr<StateDescriptor> Initialize(ParameterInput *pin) { | |||
| destroy_particles_frac >= 0. && destroy_particles_frac <= 1., | |||
| "Fraction of particles to destroy each timestep must be between 0 and 1"); | |||
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| Real defrag_threshold = pin->GetOrAddReal("Particles", "defrag_threshold", 0.9); | |||
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Useful to be able to control this at runtime.
pdmullen
approved these changes
Oct 5, 2024
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PR Summary
There was a bug in the defragmentation routine acting on particle lists. The issue was that empty indices weren't being updated after defragmentation. This PR fixes that.
As an aside: this produced the surprising effect that simulation correctness depended on frequency of simulation output, even when no particle fields were being output. This is because particle defragmentation is called during every output cycle. Not saying we can't do this, just mentioning it because it was unexpected. Shouldn't be a correctness issue if defragmentation actually works :)
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