diff --git a/include/openmc/physics_common.h b/include/openmc/physics_common.h index e38a3c7f883..b0e395c1ea4 100644 --- a/include/openmc/physics_common.h +++ b/include/openmc/physics_common.h @@ -13,5 +13,9 @@ namespace openmc { //! \param[in] weight_survive Weight assigned to particles that survive void russian_roulette(Particle& p, double weight_survive); +//! \brief Performs the global russian roulette operation on a particle +//! \param[in,out] p Particle object +void apply_russian_roulette(Particle& p); + } // namespace openmc #endif // OPENMC_PHYSICS_COMMON_H diff --git a/include/openmc/weight_windows.h b/include/openmc/weight_windows.h index 7638155228e..2fe4d7d0f15 100644 --- a/include/openmc/weight_windows.h +++ b/include/openmc/weight_windows.h @@ -25,17 +25,6 @@ enum class WeightWindowUpdateMethod { MAGIC, FW_CADIS }; constexpr double DEFAULT_WEIGHT_CUTOFF {1.0e-38}; // default low weight cutoff -//============================================================================== -// Non-member functions -//============================================================================== - -//! Apply weight windows to a particle -//! \param[in] p Particle to apply weight windows to -void apply_weight_windows(Particle& p); - -//! Free memory associated with weight windows -void free_memory_weight_windows(); - //============================================================================== // Global variables //============================================================================== @@ -237,6 +226,26 @@ class WeightWindowsGenerator { double ratio_ {5.0}; //(p.type()); @@ -153,18 +162,9 @@ void sample_neutron_reaction(Particle& p) advance_prn_seed(data::nuclides.size(), &p.seeds(STREAM_URR_PTABLE)); } - // Play russian roulette if survival biasing is turned on - if (settings::survival_biasing) { - // if survival normalization is on, use normalized weight cutoff and - // normalized weight survive - if (settings::survival_normalization) { - if (p.wgt() < settings::weight_cutoff * p.wgt_born()) { - russian_roulette(p, settings::weight_survive * p.wgt_born()); - } - } else if (p.wgt() < settings::weight_cutoff) { - russian_roulette(p, settings::weight_survive); - } - } + // Play russian roulette if there are no weight windows + if (!settings::weight_windows_on) + apply_russian_roulette(p); } void create_fission_sites(Particle& p, int i_nuclide, const Reaction& rx) diff --git a/src/physics_common.cpp b/src/physics_common.cpp index e25ae6b97ab..10760ce2da1 100644 --- a/src/physics_common.cpp +++ b/src/physics_common.cpp @@ -18,4 +18,20 @@ void russian_roulette(Particle& p, double weight_survive) } } +void apply_russian_roulette(Particle& p) +{ + // Exit if survival biasing is turned off + if (!settings::survival_biasing) + return; + + // if survival normalization is on, use normalized weight cutoff and + // normalized weight survive + if (settings::survival_normalization) { + if (p.wgt() < settings::weight_cutoff * p.wgt_born()) { + russian_roulette(p, settings::weight_survive * p.wgt_born()); + } + } else if (p.wgt() < settings::weight_cutoff) { + russian_roulette(p, settings::weight_survive); + } +} } // namespace openmc diff --git a/src/physics_mg.cpp b/src/physics_mg.cpp index 4c28cb1795a..4dfcb40ad17 100644 --- a/src/physics_mg.cpp +++ b/src/physics_mg.cpp @@ -31,8 +31,17 @@ void collision_mg(Particle& p) // Sample the reaction type sample_reaction(p); - if (settings::weight_window_checkpoint_collision) - apply_weight_windows(p); + if (settings::weight_windows_on) { + auto ww = search_weight_window(p); + if (!ww.is_valid()) { + // if the weight window is not valid, apply russian roulette + // (regardless of weight window collision checkpoint setting) + apply_russian_roulette(p); + } else if (settings::weight_window_checkpoint_collision) { + // if collision checkpointing is on, apply weight window + apply_weight_window(p, ww); + } + } // Display information about collision if ((settings::verbosity >= 10) || p.trace()) { @@ -66,18 +75,9 @@ void sample_reaction(Particle& p) // Sample a scattering event to determine the energy of the exiting neutron scatter(p); - // Play Russian roulette if survival biasing is turned on - if (settings::survival_biasing) { - // if survival normalization is applicable, use normalized weight cutoff and - // normalized weight survive - if (settings::survival_normalization) { - if (p.wgt() < settings::weight_cutoff * p.wgt_born()) { - russian_roulette(p, settings::weight_survive * p.wgt_born()); - } - } else if (p.wgt() < settings::weight_cutoff) { - russian_roulette(p, settings::weight_survive); - } - } + // Play russian roulette if there are no weight windows + if (!settings::weight_windows_on) + apply_russian_roulette(p); } void scatter(Particle& p) diff --git a/src/settings.cpp b/src/settings.cpp index 5b472468fc4..65790277d80 100644 --- a/src/settings.cpp +++ b/src/settings.cpp @@ -1264,6 +1264,13 @@ void read_settings_xml(pugi::xml_node root) } } + if (weight_windows_on) { + if (!weight_window_checkpoint_surface && + !weight_window_checkpoint_collision) + fatal_error( + "Weight Windows are enabled but there are no valid checkpoints."); + } + if (check_for_node(root, "use_decay_photons")) { settings::use_decay_photons = get_node_value_bool(root, "use_decay_photons"); diff --git a/src/weight_windows.cpp b/src/weight_windows.cpp index 4838e459152..dbd9a38ea2d 100644 --- a/src/weight_windows.cpp +++ b/src/weight_windows.cpp @@ -49,108 +49,6 @@ openmc::vector> weight_windows_generators; } // namespace variance_reduction -//============================================================================== -// Non-member functions -//============================================================================== - -void apply_weight_windows(Particle& p) -{ - if (!settings::weight_windows_on) - return; - - // WW on photon and neutron only - if (p.type() != ParticleType::neutron && p.type() != ParticleType::photon) - return; - - // skip dead or no energy - if (p.E() <= 0 || !p.alive()) - return; - - bool in_domain = false; - // TODO: this is a linear search - should do something more clever - WeightWindow weight_window; - for (const auto& ww : variance_reduction::weight_windows) { - weight_window = ww->get_weight_window(p); - if (weight_window.is_valid()) - break; - } - - // If particle has not yet had its birth weight window value set, set it to - // the current weight window (or 1.0 if not born in a weight window). - if (p.wgt_ww_born() == -1.0) { - if (weight_window.is_valid()) { - p.wgt_ww_born() = - (weight_window.lower_weight + weight_window.upper_weight) / 2; - } else { - p.wgt_ww_born() = 1.0; - } - } - - // particle is not in any of the ww domains, do nothing - if (!weight_window.is_valid()) - return; - - // Normalize weight windows based on particle's starting weight - // and the value of the weight window the particle was born in. - weight_window.scale(p.wgt_born() / p.wgt_ww_born()); - - // get the paramters - double weight = p.wgt(); - - // first check to see if particle should be killed for weight cutoff - if (p.wgt() < weight_window.weight_cutoff) { - p.wgt() = 0.0; - return; - } - - // check if particle is far above current weight window - // only do this if the factor is not already set on the particle and a - // maximum lower bound ratio is specified - if (p.ww_factor() == 0.0 && weight_window.max_lb_ratio > 1.0 && - p.wgt() > weight_window.lower_weight * weight_window.max_lb_ratio) { - p.ww_factor() = - p.wgt() / (weight_window.lower_weight * weight_window.max_lb_ratio); - } - - // move weight window closer to the particle weight if needed - if (p.ww_factor() > 1.0) - weight_window.scale(p.ww_factor()); - - // if particle's weight is above the weight window split until they are within - // the window - if (weight > weight_window.upper_weight) { - // do not further split the particle if above the limit - if (p.n_split() >= settings::max_history_splits) - return; - - double n_split = std::ceil(weight / weight_window.upper_weight); - double max_split = weight_window.max_split; - n_split = std::min(n_split, max_split); - - p.n_split() += n_split; - - // Create secondaries and divide weight among all particles - int i_split = std::round(n_split); - for (int l = 0; l < i_split - 1; l++) { - p.split(weight / n_split); - } - // remaining weight is applied to current particle - p.wgt() = weight / n_split; - - } else if (weight <= weight_window.lower_weight) { - // if the particle weight is below the window, play Russian roulette - double weight_survive = - std::min(weight * weight_window.max_split, weight_window.survival_weight); - russian_roulette(p, weight_survive); - } // else particle is in the window, continue as normal -} - -void free_memory_weight_windows() -{ - variance_reduction::ww_map.clear(); - variance_reduction::weight_windows.clear(); -} - //============================================================================== // WeightWindowSettings implementation //============================================================================== @@ -379,6 +277,13 @@ WeightWindow WeightWindows::get_weight_window(const Particle& p) const return {}; } + // particle energy + double E = p.E(); + + // check to make sure energy is in range, expects sorted energy values + if (E < energy_bounds_.front() || E > energy_bounds_.back()) + return {}; + // Get mesh index for particle's position const auto& mesh = this->mesh(); int mesh_bin = mesh->get_bin(p.r()); @@ -387,13 +292,6 @@ WeightWindow WeightWindows::get_weight_window(const Particle& p) const if (mesh_bin < 0) return {}; - // particle energy - double E = p.E(); - - // check to make sure energy is in range, expects sorted energy values - if (E < energy_bounds_.front() || E > energy_bounds_.back()) - return {}; - // get the mesh bin in energy group int energy_bin = lower_bound_index(energy_bounds_.begin(), energy_bounds_.end(), E); @@ -997,6 +895,117 @@ void WeightWindowsGenerator::update() const // Non-member functions //============================================================================== +WeightWindow search_weight_window(const Particle& p) +{ + // TODO: this is a linear search - should do something more clever + int mesh_bin; + WeightWindow weight_window; + for (const auto& ww : variance_reduction::weight_windows) { + weight_window = ww->get_weight_window(p); + if (weight_window.is_valid()) + return weight_window; + } + return {}; +} + +void apply_weight_windows(Particle& p) +{ + if (!settings::weight_windows_on) + return; + + // WW on photon and neutron only + if (p.type() != ParticleType::neutron && p.type() != ParticleType::photon) + return; + + // skip dead or no energy + if (p.E() <= 0 || !p.alive()) + return; + + auto ww = search_weight_window(p); + if (ww.is_valid()) { + apply_weight_window(p, ww); + } else { + if (p.wgt_ww_born() == -1.0) + p.wgt_ww_born() = 1.0; + } +} + +void apply_weight_window(Particle& p, WeightWindow weight_window) +{ + if (!weight_window.is_valid()) + return; + + // skip dead or no energy + if (p.E() <= 0 || !p.alive()) + return; + + // If particle has not yet had its birth weight window value set, set it to + // the current weight window. + if (p.wgt_ww_born() == -1.0) + p.wgt_ww_born() = + (weight_window.lower_weight + weight_window.upper_weight) / 2; + + // Normalize weight windows based on particle's starting weight + // and the value of the weight window the particle was born in. + weight_window.scale(p.wgt_born() / p.wgt_ww_born()); + + // get the paramters + double weight = p.wgt(); + + // first check to see if particle should be killed for weight cutoff + if (p.wgt() < weight_window.weight_cutoff) { + p.wgt() = 0.0; + return; + } + + // check if particle is far above current weight window + // only do this if the factor is not already set on the particle and a + // maximum lower bound ratio is specified + if (p.ww_factor() == 0.0 && weight_window.max_lb_ratio > 1.0 && + p.wgt() > weight_window.lower_weight * weight_window.max_lb_ratio) { + p.ww_factor() = + p.wgt() / (weight_window.lower_weight * weight_window.max_lb_ratio); + } + + // move weight window closer to the particle weight if needed + if (p.ww_factor() > 1.0) + weight_window.scale(p.ww_factor()); + + // if particle's weight is above the weight window split until they are within + // the window + if (weight > weight_window.upper_weight) { + // do not further split the particle if above the limit + if (p.n_split() >= settings::max_history_splits) + return; + + double n_split = std::ceil(weight / weight_window.upper_weight); + double max_split = weight_window.max_split; + n_split = std::min(n_split, max_split); + + p.n_split() += n_split; + + // Create secondaries and divide weight among all particles + int i_split = std::round(n_split); + for (int l = 0; l < i_split - 1; l++) { + p.split(weight / n_split); + } + // remaining weight is applied to current particle + p.wgt() = weight / n_split; + + } else if (weight <= weight_window.lower_weight) { + // if the particle weight is below the window, play Russian roulette + double weight_survive = + std::min(weight * weight_window.max_split, weight_window.survival_weight); + russian_roulette(p, weight_survive); + } // else particle is in the window, continue as normal +} + +void free_memory_weight_windows() +{ + variance_reduction::ww_map.clear(); + variance_reduction::weight_windows.clear(); +} + void finalize_variance_reduction() { for (const auto& wwg : variance_reduction::weight_windows_generators) {