22654533986

Committed 04 Mar 2026 12:48AM UTC coverage: 74.268% (+0.08%) from 74.192%

Build # 22654533986

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Merge pull request #960 from andrsd/fv-removal

Removing finite-volume spatial discretization

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81.36

/modules/linear_boltzmann_solvers/lbs_problem/lbs_problem.cc

// SPDX-FileCopyrightText: 2024 The OpenSn Authors <https://open-sn.github.io/opensn/>
// SPDX-License-Identifier: MIT

#include "modules/linear_boltzmann_solvers/lbs_problem/lbs_problem.h"
#include "modules/linear_boltzmann_solvers/discrete_ordinates_problem/discrete_ordinates_problem.h"
#include "modules/linear_boltzmann_solvers/lbs_problem/iterative_methods/wgs_context.h"
#include "modules/linear_boltzmann_solvers/lbs_problem/iterative_methods/ags_linear_solver.h"
#include "modules/linear_boltzmann_solvers/lbs_problem/point_source/point_source.h"
#include "modules/linear_boltzmann_solvers/lbs_problem/groupset/lbs_groupset.h"
#include "framework/field_functions/field_function_grid_based.h"
#include "framework/materials/multi_group_xs/multi_group_xs.h"
#include "framework/mesh/mesh_continuum/mesh_continuum.h"
#include "framework/utils/hdf_utils.h"
#include "framework/object_factory.h"
#include "framework/logging/log.h"
#include "framework/runtime.h"
#include "framework/data_types/allowable_range.h"
#include "caliper/cali.h"
#include <algorithm>
#include <iomanip>
#include <fstream>
#include <cstring>
#include <cassert>
#include <memory>
#include <stdexcept>
#include <sys/stat.h>

namespace opensn
{

InputParameters
LBSProblem::GetInputParameters()
{
  InputParameters params = Problem::GetInputParameters();

  params.ChangeExistingParamToOptional("name", "LBSProblem");

  params.AddRequiredParameter<std::shared_ptr<MeshContinuum>>("mesh", "Mesh");

  params.AddRequiredParameter<unsigned int>("num_groups",
                                            "The total number of groups within the solver");

  params.AddRequiredParameterArray("groupsets",
                                   "An array of blocks each specifying the input parameters for a "
                                   "<TT>LBSGroupset</TT>.");
  params.LinkParameterToBlock("groupsets", "LBSGroupset");

  params.AddRequiredParameterArray("xs_map",
                                   "Cross-section map from block IDs to cross-section objects.");

  params.AddOptionalParameterArray<std::shared_ptr<VolumetricSource>>(
    "volumetric_sources", {}, "An array of handles to volumetric sources.");

  params.AddOptionalParameterArray<std::shared_ptr<PointSource>>(
    "point_sources", {}, "An array of point sources.");

  params.AddOptionalParameterBlock(
    "options", ParameterBlock(), "Block of options. See <TT>OptionsBlock</TT>.");
  params.LinkParameterToBlock("options", "OptionsBlock");

  params.AddOptionalParameter("use_gpus", false, "Offload the sweep computation to GPUs.");

  return params;
}

LBSProblem::LBSProblem(const InputParameters& params)
  : Problem(params),
    num_groups_(params.GetParamValue<unsigned int>("num_groups")),
    grid_(params.GetSharedPtrParam<MeshContinuum>("mesh")),
    use_gpus_(params.GetParamValue<bool>("use_gpus"))
{
  // Check system for GPU acceleration
  if (use_gpus_)
  {
#ifdef __OPENSN_WITH_GPU__
    CheckCapableDevices();
#else
    throw std::invalid_argument(
      GetName() + ": GPU support was requested, but OpenSn was built without CUDA enabled.");
#endif // __OPENSN_WITH_GPU__
  }

  // Initialize options
  if (params.IsParameterValid("options"))
  {
    auto options_params = LBSProblem::GetOptionsBlock();
    options_params.AssignParameters(params.GetParam("options"));
    ParseOptions(options_params);
  }
  applied_adjoint_ = options_.adjoint;
  applied_save_angular_flux_ = options_.save_angular_flux;

  // Set geometry type
  geometry_type_ = grid_->GetGeometryType();
  if (geometry_type_ == GeometryType::INVALID)
    throw std::runtime_error(GetName() + ": Invalid geometry type.");

  InitializeGroupsets(params);
  InitializeSources(params);
  InitializeXSmapAndDensities(params);
  InitializeMaterials();
}

LBSOptions&
LBSProblem::GetOptions()
{
  return options_;
}

const LBSOptions&
LBSProblem::GetOptions() const
{
  return options_;
}

double
LBSProblem::GetTime() const
{
  return time_;
}

void
LBSProblem::SetTime(double time)
{
  time_ = time;
}

void
LBSProblem::SetTimeStep(double dt)
{
  if (dt <= 0.0)
    throw std::runtime_error(GetName() + " dt must be greater than zero.");
  dt_ = dt;
}

double
LBSProblem::GetTimeStep() const
{
  return dt_;
}

void
LBSProblem::SetTheta(double theta)
{
  if (theta <= 0.0 or theta > 1.0)
    throw std::runtime_error(GetName() + " theta must be in (0.0, 1.0].");
  theta_ = theta;
}

double
LBSProblem::GetTheta() const
{
  return theta_;
}

bool
LBSProblem::IsTimeDependent() const
{
  return false;
}

void
LBSProblem::SetTimeDependentMode()
{
  throw std::logic_error(GetName() +
                         ": Time-dependent mode is not supported for this problem type.");
}

void
LBSProblem::SetSteadyStateMode()
{
  // Steady-state is the default for problem types without time-dependent support.
}

GeometryType
LBSProblem::GetGeometryType() const
{
  return geometry_type_;
}

unsigned int
LBSProblem::GetNumMoments() const
{
  return num_moments_;
}

unsigned int
LBSProblem::GetMaxCellDOFCount() const
{
  return max_cell_dof_count_;
}

unsigned int
LBSProblem::GetMinCellDOFCount() const
{
  return min_cell_dof_count_;
}

bool
LBSProblem::UseGPUs() const
{
  return use_gpus_;
}

unsigned int
LBSProblem::GetNumGroups() const
{
  return num_groups_;
}

unsigned int
LBSProblem::GetScatteringOrder() const
{
  return scattering_order_;
}

unsigned int
LBSProblem::GetNumPrecursors() const
{
  return num_precursors_;
}

unsigned int
LBSProblem::GetMaxPrecursorsPerMaterial() const
{
  return max_precursors_per_material_;
}

std::vector<LBSGroupset>&
LBSProblem::GetGroupsets()
{
  return groupsets_;
}

const std::vector<LBSGroupset>&
LBSProblem::GetGroupsets() const
{
  return groupsets_;
}

void
LBSProblem::AddPointSource(std::shared_ptr<PointSource> point_source)
{
  point_sources_.push_back(point_source);
  if (initialized_)
    point_sources_.back()->Initialize(*this);
}

void
LBSProblem::ClearPointSources()
{
  point_sources_.clear();
}

const std::vector<std::shared_ptr<PointSource>>&
LBSProblem::GetPointSources() const
{
  return point_sources_;
}

void
LBSProblem::AddVolumetricSource(std::shared_ptr<VolumetricSource> volumetric_source)
{
  volumetric_sources_.push_back(volumetric_source);
  if (initialized_)
    volumetric_sources_.back()->Initialize(*this);
}

void
LBSProblem::ClearVolumetricSources()
{
  volumetric_sources_.clear();
}

const std::vector<std::shared_ptr<VolumetricSource>>&
LBSProblem::GetVolumetricSources() const
{
  return volumetric_sources_;
}

const BlockID2XSMap&
LBSProblem::GetBlockID2XSMap() const
{
  return block_id_to_xs_map_;
}

void
LBSProblem::SetBlockID2XSMap(const BlockID2XSMap& xs_map)
{
  block_id_to_xs_map_ = xs_map;
  InitializeMaterials();
  ResetGPUCarriers();
  InitializeGPUExtras();
}

std::shared_ptr<MeshContinuum>
LBSProblem::GetGrid() const
{
  return grid_;
}

const SpatialDiscretization&
LBSProblem::GetSpatialDiscretization() const
{
  return *discretization_;
}

const std::vector<UnitCellMatrices>&
LBSProblem::GetUnitCellMatrices() const
{
  return unit_cell_matrices_;
}

const std::map<uint64_t, UnitCellMatrices>&
LBSProblem::GetUnitGhostCellMatrices() const
{
  return unit_ghost_cell_matrices_;
}

std::vector<CellLBSView>&
LBSProblem::GetCellTransportViews()
{
  return cell_transport_views_;
}

const std::vector<CellLBSView>&
LBSProblem::GetCellTransportViews() const
{
  return cell_transport_views_;
}

const UnknownManager&
LBSProblem::GetUnknownManager() const
{
  return flux_moments_uk_man_;
}

size_t
LBSProblem::GetLocalNodeCount() const
{
  return local_node_count_;
}

size_t
LBSProblem::GetGlobalNodeCount() const
{
  return global_node_count_;
}

std::vector<double>&
LBSProblem::GetQMomentsLocal()
{
  return q_moments_local_;
}

const std::vector<double>&
LBSProblem::GetQMomentsLocal() const
{
  return q_moments_local_;
}

std::vector<double>&
LBSProblem::GetExtSrcMomentsLocal()
{
  return ext_src_moments_local_;
}

const std::vector<double>&
LBSProblem::GetExtSrcMomentsLocal() const
{
  return ext_src_moments_local_;
}

std::vector<double>&
LBSProblem::GetPhiOldLocal()
{
  return phi_old_local_;
}

const std::vector<double>&
LBSProblem::GetPhiOldLocal() const
{
  return phi_old_local_;
}

std::vector<double>&
LBSProblem::GetPhiNewLocal()
{
  return phi_new_local_;
}

const std::vector<double>&
LBSProblem::GetPhiNewLocal() const
{
  return phi_new_local_;
}

std::vector<double>&
LBSProblem::GetPrecursorsNewLocal()
{
  return precursor_new_local_;
}

const std::vector<double>&
LBSProblem::GetPrecursorsNewLocal() const
{
  return precursor_new_local_;
}

std::vector<double>&
LBSProblem::GetDensitiesLocal()
{
  return densities_local_;
}

const std::vector<double>&
LBSProblem::GetDensitiesLocal() const
{
  return densities_local_;
}

SetSourceFunction
LBSProblem::GetActiveSetSourceFunction() const
{
  return active_set_source_function_;
}

void
LBSProblem::SetActiveSetSourceFunction(SetSourceFunction source_function)
{
  active_set_source_function_ = std::move(source_function);
}

std::shared_ptr<AGSLinearSolver>
LBSProblem::GetAGSSolver()
{
  return ags_solver_;
}

std::vector<std::shared_ptr<LinearSolver>>&
LBSProblem::GetWGSSolvers()
{
  return wgs_solvers_;
}

WGSContext&
LBSProblem::GetWGSContext(int groupset_id)
{
  auto& wgs_solver = wgs_solvers_[groupset_id];
  auto raw_context = wgs_solver->GetContext();
  auto wgs_context_ptr = std::dynamic_pointer_cast<WGSContext>(raw_context);
  OpenSnLogicalErrorIf(not wgs_context_ptr, "Failed to cast WGSContext");
  return *wgs_context_ptr;
}

std::pair<size_t, size_t>
LBSProblem::GetNumPhiIterativeUnknowns()
{
  const auto& sdm = *discretization_;
  const size_t num_local_phi_dofs = sdm.GetNumLocalDOFs(flux_moments_uk_man_);
  const size_t num_global_phi_dofs = sdm.GetNumGlobalDOFs(flux_moments_uk_man_);

  return {num_local_phi_dofs, num_global_phi_dofs};
}

std::shared_ptr<FieldFunctionGridBased>
LBSProblem::GetScalarFluxFieldFunction(unsigned int g, unsigned int m) const
{
  OpenSnLogicalErrorIf(g >= num_groups_, "Group index out of range.");
  OpenSnLogicalErrorIf(m >= num_moments_, "Moment index out of range.");

  const auto map_it = phi_field_functions_local_map_.find({g, m});
  OpenSnLogicalErrorIf(map_it == phi_field_functions_local_map_.end(),
                       std::string("Failure to map phi field function g") + std::to_string(g) +
                         " m" + std::to_string(m));

  return field_functions_.at(map_it->second);
}

std::shared_ptr<FieldFunctionGridBased>
LBSProblem::GetPowerFieldFunction() const
{
  OpenSnLogicalErrorIf(not options_.power_field_function_on,
                       "Called when options_.power_field_function_on == false");

  return field_functions_[power_gen_fieldfunc_local_handle_];
}

InputParameters
LBSProblem::GetOptionsBlock()
{
  InputParameters params;

  params.SetGeneralDescription("Set options from a large list of parameters");
  params.AddOptionalParameter("max_mpi_message_size",
                              32768,
                              "The maximum MPI message size used during sweep initialization.");
  params.AddOptionalParameter(
    "restart_writes_enabled", false, "Flag that controls writing of restart dumps");
  params.AddOptionalParameter("write_delayed_psi_to_restart",
                              true,
                              "Flag that controls writing of delayed angular fluxes to restarts.");
  params.AddOptionalParameter(
    "read_restart_path", "", "Full path for reading restart dumps including file stem.");
  params.AddOptionalParameter(
    "write_restart_path", "", "Full path for writing restart dumps including file stem.");
  params.AddOptionalParameter("write_restart_time_interval",
                              0,
                              "Time interval in seconds at which restart data is to be written.");
  params.AddOptionalParameter(
    "use_precursors", false, "Flag for using delayed neutron precursors.");
  params.AddOptionalParameter("use_source_moments",
                              false,
                              "Flag for ignoring fixed sources and selectively using source "
                              "moments obtained elsewhere.");
  params.AddOptionalParameter(
    "save_angular_flux", false, "Flag indicating whether angular fluxes are to be stored or not.");
  params.AddOptionalParameter(
    "adjoint", false, "Flag for toggling whether the solver is in adjoint mode.");
  params.AddOptionalParameter(
    "verbose_inner_iterations", true, "Flag to control verbosity of inner iterations.");
  params.AddOptionalParameter(
    "verbose_outer_iterations", true, "Flag to control verbosity of across-groupset iterations.");
  params.AddOptionalParameter(
    "max_ags_iterations", 100, "Maximum number of across-groupset iterations.");
  params.AddOptionalParameter("ags_tolerance", 1.0e-6, "Across-groupset iterations tolerance.");
  params.AddOptionalParameter("ags_convergence_check",
                              "l2",
                              "Type of convergence check for AGS iterations. Valid values are "
                              "`\"l2\"` and '\"pointwise\"'");
  params.AddOptionalParameter(
    "verbose_ags_iterations", true, "Flag to control verbosity of across-groupset iterations.");
  params.AddOptionalParameter("power_field_function_on",
                              false,
                              "Flag to control the creation of the power generation field "
                              "function. If set to `true` then a field function will be created "
                              "with the general name <solver_name>_power_generation`.");
  params.AddOptionalParameter("power_default_kappa",
                              3.20435e-11,
                              "Default `kappa` value (Energy released per fission) to use for "
                              "power generation when cross sections do not have `kappa` values. "
                              "Default: 3.20435e-11 Joule (corresponding to 200 MeV per fission).");
  params.AddOptionalParameter("power_normalization",
                              -1.0,
                              "Power normalization factor to use. Supply a negative or zero number "
                              "to turn this off.");
  params.AddOptionalParameter("field_function_prefix_option",
                              "prefix",
                              "Prefix option on field function names. Default: `\"prefix\"`. Can "
                              "be `\"prefix\"` or `\"solver_name\"`. By default this option uses "
                              "the value of the `field_function_prefix` parameter. If this "
                              "parameter is not set, flux field functions will be exported as "
                              "`phi_gXXX_mYYY` where `XXX` is the zero padded 3 digit group number "
                              "and `YYY` is the zero padded 3 digit moment.");
  params.AddOptionalParameter("field_function_prefix",
                              "",
                              "Prefix to use on all field functions. Default: `\"\"`. By default "
                              "this option is empty. Ff specified, flux moments will be exported "
                              "as `prefix_phi_gXXX_mYYY` where `XXX` is the zero padded 3 digit "
                              "group number and `YYY` is the zero padded 3 digit moment. The "
                              "underscore after \"prefix\" is added automatically.");
  params.ConstrainParameterRange("ags_convergence_check",
                                 AllowableRangeList::New({"l2", "pointwise"}));
  params.ConstrainParameterRange("field_function_prefix_option",
                                 AllowableRangeList::New({"prefix", "solver_name"}));
  params.ConstrainParameterRange("max_mpi_message_size", AllowableRangeLowLimit::New(1024));
  params.ConstrainParameterRange("write_restart_time_interval", AllowableRangeLowLimit::New(0));
  params.ConstrainParameterRange("max_ags_iterations", AllowableRangeLowLimit::New(0));
  params.ConstrainParameterRange("ags_tolerance", AllowableRangeLowLimit::New(1.0e-18));
  params.ConstrainParameterRange("power_default_kappa", AllowableRangeLowLimit::New(0.0, false));

  return params;
}

InputParameters
LBSProblem::GetXSMapEntryBlock()
{
  InputParameters params;
  params.SetGeneralDescription("Set the cross-section map for the solver.");
  params.AddRequiredParameterArray("block_ids", "Mesh block IDs");
  params.AddRequiredParameter<std::shared_ptr<MultiGroupXS>>("xs", "Cross-section object");
  return params;
}

void
LBSProblem::SetOptions(const InputParameters& input)
{
  ParseOptions(input);
  ApplyOptions();
}

void
LBSProblem::ParseOptions(const InputParameters& input)
{
  auto params = LBSProblem::GetOptionsBlock();
  params.AssignParameters(input);
  const auto& params_at_assignment = input.GetParametersAtAssignment();
  const auto& specified_params = params_at_assignment.GetNumParameters() > 0
                                   ? params_at_assignment
                                   : static_cast<const ParameterBlock&>(input);

  // Apply only options explicitly specified by the caller.
  for (const auto& spec : specified_params.GetParameters())
  {
    if (spec.GetName() == "max_mpi_message_size")
      options_.max_mpi_message_size = spec.GetValue<int>();

    else if (spec.GetName() == "restart_writes_enabled")
      options_.restart_writes_enabled = spec.GetValue<bool>();

    else if (spec.GetName() == "write_delayed_psi_to_restart")
      options_.write_delayed_psi_to_restart = spec.GetValue<bool>();

    else if (spec.GetName() == "read_restart_path")
    {
      options_.read_restart_path = spec.GetValue<std::string>();
      if (not options_.read_restart_path.empty())
        options_.read_restart_path += std::to_string(opensn::mpi_comm.rank()) + ".restart.h5";
    }

    else if (spec.GetName() == "write_restart_path")
    {
      options_.write_restart_path = spec.GetValue<std::string>();
      if (not options_.write_restart_path.empty())
        options_.write_restart_path += std::to_string(opensn::mpi_comm.rank()) + ".restart.h5";
    }

    else if (spec.GetName() == "write_restart_time_interval")
      options_.write_restart_time_interval = std::chrono::seconds(spec.GetValue<int>());

    else if (spec.GetName() == "use_precursors")
      options_.use_precursors = spec.GetValue<bool>();

    else if (spec.GetName() == "use_source_moments")
      options_.use_src_moments = spec.GetValue<bool>();

    else if (spec.GetName() == "save_angular_flux")
      options_.save_angular_flux = spec.GetValue<bool>();

    else if (spec.GetName() == "verbose_inner_iterations")
      options_.verbose_inner_iterations = spec.GetValue<bool>();

    else if (spec.GetName() == "max_ags_iterations")
      options_.max_ags_iterations = spec.GetValue<int>();

    else if (spec.GetName() == "ags_tolerance")
      options_.ags_tolerance = spec.GetValue<double>();

    else if (spec.GetName() == "ags_convergence_check")
    {
      auto check = spec.GetValue<std::string>();
      options_.ags_pointwise_convergence = (check == "pointwise");
    }

    else if (spec.GetName() == "verbose_ags_iterations")
      options_.verbose_ags_iterations = spec.GetValue<bool>();

    else if (spec.GetName() == "verbose_outer_iterations")
      options_.verbose_outer_iterations = spec.GetValue<bool>();

    else if (spec.GetName() == "power_field_function_on")
      options_.power_field_function_on = spec.GetValue<bool>();

    else if (spec.GetName() == "power_default_kappa")
      options_.power_default_kappa = spec.GetValue<double>();

    else if (spec.GetName() == "power_normalization")
      options_.power_normalization = spec.GetValue<double>();

    else if (spec.GetName() == "field_function_prefix_option")
    {
      options_.field_function_prefix_option = spec.GetValue<std::string>();
    }

    else if (spec.GetName() == "field_function_prefix")
      options_.field_function_prefix = spec.GetValue<std::string>();

    else if (spec.GetName() == "adjoint")
      options_.adjoint = spec.GetValue<bool>();

  } // for specified options

  OpenSnInvalidArgumentIf(options_.write_restart_time_interval > std::chrono::seconds(0) and
                            not options_.restart_writes_enabled,
                          GetName() + ": `write_restart_time_interval>0` requires "
                                      "`restart_writes_enabled=true`.");

  OpenSnInvalidArgumentIf(options_.write_restart_time_interval > std::chrono::seconds(0) and
                            options_.write_restart_time_interval < std::chrono::seconds(30),
                          GetName() + ": `write_restart_time_interval` must be 0 (disabled) "
                                      "or at least 30 seconds.");

  OpenSnInvalidArgumentIf(options_.restart_writes_enabled and options_.write_restart_path.empty(),
                          GetName() + ": `restart_writes_enabled=true` requires a non-empty "
                                      "`write_restart_path`.");

  OpenSnInvalidArgumentIf(not options_.field_function_prefix.empty() and
                            options_.field_function_prefix_option != "prefix",
                          GetName() + ": non-empty `field_function_prefix` requires "
                                      "`field_function_prefix_option=\"prefix\"`.");

  if (options_.restart_writes_enabled)
  {
    const auto dir = options_.write_restart_path.parent_path();

    // Create restart directory if necessary.
    // If dir is empty, write path resolves relative to the working directory.
    if ((not dir.empty()) and opensn::mpi_comm.rank() == 0)
    {
      if (not std::filesystem::exists(dir))
      {
        if (not std::filesystem::create_directories(dir))
          throw std::runtime_error(GetName() + ": Failed to create restart directory " +
                                   dir.string());
      }
      else if (not std::filesystem::is_directory(dir))
        throw std::runtime_error(GetName() + ": Restart path exists but is not a directory " +
                                 dir.string());
    }
    opensn::mpi_comm.barrier();
    UpdateRestartWriteTime();
  }
}

void
LBSProblem::ApplyOptions()
{
  if (not initialized_)
    return;

  if (options_.adjoint != applied_adjoint_)
    SetAdjoint(options_.adjoint);

  if (options_.save_angular_flux != applied_save_angular_flux_)
    SetSaveAngularFlux(options_.save_angular_flux);
}

void
LBSProblem::BuildRuntime()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::BuildRuntime");
  if (initialized_)
    return;

  PrintSimHeader();
  mpi_comm.barrier();

  InitializeSpatialDiscretization();
  InitializeParrays();
  InitializeBoundaries();
  InitializeGPUExtras();
  if (options_.adjoint)
    if (const auto* do_problem = dynamic_cast<const DiscreteOrdinatesProblem*>(this);
        do_problem and do_problem->IsTimeDependent())
      throw std::runtime_error(GetName() + ": Time-dependent adjoint problems are not supported.");

  // Initialize point sources
  for (auto& point_source : point_sources_)
    point_source->Initialize(*this);

  // Initialize volumetric sources
  for (auto& volumetric_source : volumetric_sources_)
    volumetric_source->Initialize(*this);

  initialized_ = true;
}

void
LBSProblem::PrintSimHeader()
{
  if (opensn::mpi_comm.rank() == 0)
  {
    std::stringstream outstr;
    outstr << "\n"
           << "Initializing " << GetName() << "\n\n"
           << "Scattering order    : " << scattering_order_ << "\n"
           << "Number of moments   : " << num_moments_ << "\n"
           << "Number of groups    : " << num_groups_ << "\n"
           << "Number of groupsets : " << groupsets_.size() << "\n\n";

    for (const auto& groupset : groupsets_)
    {
      outstr << "***** Groupset " << groupset.id << " *****\n"
             << "Groups:\n";
      const auto n_gs_groups = groupset.GetNumGroups();
      constexpr int groups_per_line = 12;
      for (size_t i = 0; i < n_gs_groups; ++i)
      {
        outstr << std::setw(5) << groupset.first_group + i << ' ';
        if ((i + 1) % groups_per_line == 0)
          outstr << '\n';
      }
      if (n_gs_groups > 0 && n_gs_groups % groups_per_line != 0)
        outstr << '\n';
    }

    log.Log() << outstr.str() << '\n';
  }
}

void
LBSProblem::InitializeSources(const InputParameters& params)
{
  if (params.Has("volumetric_sources"))
  {
    const auto& vol_srcs = params.GetParam("volumetric_sources");
    vol_srcs.RequireBlockTypeIs(ParameterBlockType::ARRAY);
    for (const auto& src : vol_srcs)
      volumetric_sources_.push_back(src.GetValue<std::shared_ptr<VolumetricSource>>());
  }

  if (params.Has("point_sources"))
  {
    const auto& pt_srcs = params.GetParam("point_sources");
    pt_srcs.RequireBlockTypeIs(ParameterBlockType::ARRAY);
    for (const auto& src : pt_srcs)
      point_sources_.push_back(src.GetValue<std::shared_ptr<PointSource>>());
  }
}

void
LBSProblem::InitializeGroupsets(const InputParameters& params)
{
  // Initialize groups
  if (num_groups_ == 0)
    throw std::invalid_argument(GetName() + ": Number of groups must be > 0");

  // Initialize groupsets
  const auto& groupsets_array = params.GetParam("groupsets");
  const size_t num_gs = groupsets_array.GetNumParameters();
  if (num_gs == 0)
    throw std::invalid_argument(GetName() + ": At least one groupset must be specified");
  for (size_t gs = 0; gs < num_gs; ++gs)
  {
    const auto& groupset_params = groupsets_array.GetParam(gs);
    InputParameters gs_input_params = LBSGroupset::GetInputParameters();
    gs_input_params.SetObjectType("LBSProblem:LBSGroupset");
    gs_input_params.AssignParameters(groupset_params);
    groupsets_.emplace_back(gs_input_params, gs, *this);
    if (groupsets_.back().GetNumGroups() == 0)
    {
      std::stringstream oss;
      oss << GetName() << ": No groups added to groupset " << groupsets_.back().id;
      throw std::runtime_error(oss.str());
    }
  }
}

void
LBSProblem::InitializeXSmapAndDensities(const InputParameters& params)
{
  // Build XS map
  const auto& xs_array = params.GetParam("xs_map");
  const size_t num_xs = xs_array.GetNumParameters();
  for (size_t i = 0; i < num_xs; ++i)
  {
    const auto& item_params = xs_array.GetParam(i);
    InputParameters xs_entry_pars = GetXSMapEntryBlock();
    xs_entry_pars.AssignParameters(item_params);

    const auto& block_ids_param = xs_entry_pars.GetParam("block_ids");
    block_ids_param.RequireBlockTypeIs(ParameterBlockType::ARRAY);
    const auto& block_ids = block_ids_param.GetVectorValue<unsigned int>();
    auto xs = xs_entry_pars.GetSharedPtrParam<MultiGroupXS>("xs");
    for (const auto& block_id : block_ids)
      block_id_to_xs_map_[block_id] = xs;
  }

  // Assign placeholder unit densities
  densities_local_.assign(grid_->local_cells.size(), 1.0);
}

void
LBSProblem::InitializeMaterials()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::InitializeMaterials");

  log.Log0Verbose1() << "Initializing Materials";

  // Create set of material ids locally relevant
  int invalid_mat_cell_count = 0;
  std::set<unsigned int> unique_block_ids;
  for (auto& cell : grid_->local_cells)
  {
    unique_block_ids.insert(cell.block_id);
    if (cell.block_id == std::numeric_limits<unsigned int>::max() or
        (block_id_to_xs_map_.find(cell.block_id) == block_id_to_xs_map_.end()))
      ++invalid_mat_cell_count;
  }
  const auto& ghost_cell_ids = grid_->cells.GetGhostGlobalIDs();
  for (uint64_t cell_id : ghost_cell_ids)
  {
    const auto& cell = grid_->cells[cell_id];
    unique_block_ids.insert(cell.block_id);
    if (cell.block_id == std::numeric_limits<unsigned int>::max() or
        (block_id_to_xs_map_.find(cell.block_id) == block_id_to_xs_map_.end()))
      ++invalid_mat_cell_count;
  }
  OpenSnLogicalErrorIf(invalid_mat_cell_count > 0,
                       std::to_string(invalid_mat_cell_count) +
                         " cells encountered with an invalid material id.");

  // Get ready for processing
  for (const auto& [blk_id, mat] : block_id_to_xs_map_)
  {
    mat->SetAdjointMode(options_.adjoint);

    OpenSnLogicalErrorIf(mat->GetNumGroups() < num_groups_,
                         "Cross-sections for block \"" + std::to_string(blk_id) +
                           "\" have fewer groups (" + std::to_string(mat->GetNumGroups()) +
                           ") than the simulation (" + std::to_string(num_groups_) + "). " +
                           "Cross-sections must have at least as many groups as the simulation.");
  }

  // Initialize precursor properties
  num_precursors_ = 0;
  max_precursors_per_material_ = 0;
  for (const auto& mat_id_xs : block_id_to_xs_map_)
  {
    const auto& xs = mat_id_xs.second;
    num_precursors_ += xs->GetNumPrecursors();
    max_precursors_per_material_ = std::max(xs->GetNumPrecursors(), max_precursors_per_material_);
  }

  // if no precursors, turn off precursors
  if (num_precursors_ == 0)
    options_.use_precursors = false;

  // check compatibility when precursors are on
  if (options_.use_precursors)
  {
    for (const auto& [mat_id, xs] : block_id_to_xs_map_)
    {
      OpenSnLogicalErrorIf(xs->IsFissionable() and num_precursors_ == 0,
                           "Incompatible cross-section data encountered for material id " +
                             std::to_string(mat_id) + ". When delayed neutron data is present " +
                             "for one fissionable matrial, it must be present for all fissionable "
                             "materials.");
    }
  }

  // Update transport views if available
  if (grid_->local_cells.size() == cell_transport_views_.size())
    for (const auto& cell : grid_->local_cells)
    {
      const auto& xs_ptr = block_id_to_xs_map_[cell.block_id];
      auto& transport_view = cell_transport_views_[cell.local_id];
      transport_view.ReassignXS(*xs_ptr);
    }

  mpi_comm.barrier();
}

void
LBSProblem::InitializeSpatialDiscretization()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::InitializeSpatialDiscretization");

  OpenSnLogicalErrorIf(not discretization_,
                       GetName() + ": Missing spatial discretization. Construct the problem "
                                   "through its factory Create(...) entry point.");
  log.Log() << "Initializing spatial discretization metadata.\n";

  ComputeUnitIntegrals();
}

void
LBSProblem::ComputeUnitIntegrals()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::ComputeUnitIntegrals");

  log.Log() << "Computing unit integrals.\n";
  const auto& sdm = *discretization_;

  const size_t num_local_cells = grid_->local_cells.size();
  unit_cell_matrices_.resize(num_local_cells);

  for (const auto& cell : grid_->local_cells)
    unit_cell_matrices_[cell.local_id] =
      ComputeUnitCellIntegrals(sdm, cell, grid_->GetCoordinateSystem());

  const auto ghost_ids = grid_->cells.GetGhostGlobalIDs();
  for (auto ghost_id : ghost_ids)
    unit_ghost_cell_matrices_[ghost_id] =
      ComputeUnitCellIntegrals(sdm, grid_->cells[ghost_id], grid_->GetCoordinateSystem());

  // Assessing global unit cell matrix storage
  std::array<size_t, 2> num_local_ucms = {unit_cell_matrices_.size(),
                                          unit_ghost_cell_matrices_.size()};
  std::array<size_t, 2> num_global_ucms = {0, 0};

  mpi_comm.all_reduce(num_local_ucms.data(), 2, num_global_ucms.data(), mpi::op::sum<size_t>());

  opensn::mpi_comm.barrier();
  log.Log() << "Ghost cell unit cell-matrix ratio: "
            << (double)num_global_ucms[1] * 100 / (double)num_global_ucms[0] << "%";
  log.Log() << "Cell matrices computed.";
}

void
LBSProblem::InitializeParrays()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::InitializeParrays");

  log.Log() << "Initializing parallel arrays."
            << " G=" << num_groups_ << " M=" << num_moments_ << std::endl;

  // Initialize unknown
  // structure
  flux_moments_uk_man_.unknowns.clear();
  for (unsigned int m = 0; m < num_moments_; ++m)
  {
    flux_moments_uk_man_.AddUnknown(UnknownType::VECTOR_N, num_groups_);
    flux_moments_uk_man_.unknowns.back().name = "m" + std::to_string(m);
  }

  // Compute local # of dof
  local_node_count_ = discretization_->GetNumLocalNodes();
  global_node_count_ = discretization_->GetNumGlobalNodes();

  // Compute num of unknowns
  size_t local_unknown_count = local_node_count_ * num_groups_ * num_moments_;

  log.LogAllVerbose1() << "LBS Number of phi unknowns: " << local_unknown_count;

  // Size local vectors
  q_moments_local_.assign(local_unknown_count, 0.0);
  phi_old_local_.assign(local_unknown_count, 0.0);
  phi_new_local_.assign(local_unknown_count, 0.0);

  // Setup precursor vector
  if (options_.use_precursors)
  {
    size_t num_precursor_dofs = grid_->local_cells.size() * max_precursors_per_material_;
    precursor_new_local_.assign(num_precursor_dofs, 0.0);
  }

  // Initialize transport views
  // Transport views act as a data structure to store information
  // related to the transport simulation. The most prominent function
  // here is that it holds the means to know where a given cell's
  // transport quantities are located in the unknown vectors (i.e. phi)
  //
  // Also, for a given cell, within a given sweep chunk,
  // we need to solve a matrix which square size is the
  // amount of nodes on the cell. max_cell_dof_count is
  // initialized here.
  //
  size_t block_MG_counter = 0; // Counts the strides of moment and group

  const Vector3 ihat(1.0, 0.0, 0.0);
  const Vector3 jhat(0.0, 1.0, 0.0);
  const Vector3 khat(0.0, 0.0, 1.0);

  min_cell_dof_count_ = std::numeric_limits<unsigned int>::max();
  max_cell_dof_count_ = 0;
  cell_transport_views_.clear();
  cell_transport_views_.reserve(grid_->local_cells.size());
  for (auto& cell : grid_->local_cells)
  {
    size_t num_nodes = discretization_->GetCellNumNodes(cell);

    // compute cell volumes
    double cell_volume = 0.0;
    const auto& IntV_shapeI = unit_cell_matrices_[cell.local_id].intV_shapeI;
    for (size_t i = 0; i < num_nodes; ++i)
      cell_volume += IntV_shapeI(i);

    size_t cell_phi_address = block_MG_counter;

    const size_t num_faces = cell.faces.size();
    std::vector<bool> face_local_flags(num_faces, true);
    std::vector<int> face_locality(num_faces, opensn::mpi_comm.rank());
    std::vector<const Cell*> neighbor_cell_ptrs(num_faces, nullptr);
    bool cell_on_boundary = false;
    int f = 0;
    for (auto& face : cell.faces)
    {
      if (not face.has_neighbor)
      {
        cell_on_boundary = true;
        face_local_flags[f] = false;
        face_locality[f] = -1;
      } // if bndry
      else
      {
        const int neighbor_partition = face.GetNeighborPartitionID(grid_.get());
        face_local_flags[f] = (neighbor_partition == opensn::mpi_comm.rank());
        face_locality[f] = neighbor_partition;
        neighbor_cell_ptrs[f] = &grid_->cells[face.neighbor_id];
      }

      ++f;
    } // for f

    max_cell_dof_count_ = std::max(max_cell_dof_count_, static_cast<unsigned int>(num_nodes));
    min_cell_dof_count_ = std::min(min_cell_dof_count_, static_cast<unsigned int>(num_nodes));
    cell_transport_views_.emplace_back(cell_phi_address,
                                       num_nodes,
                                       num_groups_,
                                       num_moments_,
                                       num_faces,
                                       *block_id_to_xs_map_[cell.block_id],
                                       cell_volume,
                                       face_local_flags,
                                       face_locality,
                                       neighbor_cell_ptrs,
                                       cell_on_boundary);
    block_MG_counter += num_nodes * num_groups_ * num_moments_;
  } // for local cell

  // Populate grid nodal mappings
  // This is used in the Flux Data Structures (FLUDS)
  grid_nodal_mappings_.clear();
  grid_nodal_mappings_.reserve(grid_->local_cells.size());
  for (auto& cell : grid_->local_cells)
  {
    CellFaceNodalMapping cell_nodal_mapping;
    cell_nodal_mapping.reserve(cell.faces.size());

    for (auto& face : cell.faces)
    {
      std::vector<short> face_node_mapping;
      std::vector<short> cell_node_mapping;
      int adj_face_idx = -1;

      if (face.has_neighbor)
      {
        grid_->FindAssociatedVertices(face, face_node_mapping);
        grid_->FindAssociatedCellVertices(face, cell_node_mapping);
        adj_face_idx = face.GetNeighborAdjacentFaceIndex(grid_.get());
      }

      cell_nodal_mapping.emplace_back(adj_face_idx, face_node_mapping, cell_node_mapping);
    } // for f

    grid_nodal_mappings_.push_back(cell_nodal_mapping);
  } // for local cell

  // Get grid localized communicator set
  grid_local_comm_set_ = grid_->MakeMPILocalCommunicatorSet();

  // Initialize Field Functions
  InitializeFieldFunctions();

  opensn::mpi_comm.barrier();
  log.Log() << "Done with parallel arrays." << std::endl;
}

void
LBSProblem::InitializeFieldFunctions()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::InitializeFieldFunctions");

  if (not field_functions_.empty())
    return;

  // Initialize Field Functions for flux moments
  phi_field_functions_local_map_.clear();

  for (unsigned int g = 0; g < num_groups_; ++g)
  {
    for (unsigned int m = 0; m < num_moments_; ++m)
    {
      std::string prefix;
      if (options_.field_function_prefix_option == "prefix")
      {
        prefix = options_.field_function_prefix;
        if (not prefix.empty())
          prefix += "_";
      }
      if (options_.field_function_prefix_option == "solver_name")
        prefix = GetName() + "_";

      std::ostringstream oss;
      oss << prefix << "phi_g" << std::setw(3) << std::setfill('0') << static_cast<int>(g) << "_m"
          << std::setw(2) << std::setfill('0') << static_cast<int>(m);
      const std::string name = oss.str();

      auto group_ff = std::make_shared<FieldFunctionGridBased>(
        name, discretization_, Unknown(UnknownType::SCALAR));

      field_function_stack.push_back(group_ff);
      field_functions_.push_back(group_ff);

      phi_field_functions_local_map_[{g, m}] = field_functions_.size() - 1;
    } // for m
  } // for g

  // Initialize power generation field function
  if (options_.power_field_function_on)
  {
    std::string prefix;
    if (options_.field_function_prefix_option == "prefix")
    {
      prefix = options_.field_function_prefix;
      if (not prefix.empty())
        prefix += "_";
    }
    if (options_.field_function_prefix_option == "solver_name")
      prefix = GetName() + "_";

    auto power_ff = std::make_shared<FieldFunctionGridBased>(
      prefix + "power_generation", discretization_, Unknown(UnknownType::SCALAR));

    field_function_stack.push_back(power_ff);
    field_functions_.push_back(power_ff);

    power_gen_fieldfunc_local_handle_ = field_functions_.size() - 1;
  }
}

void
LBSProblem::InitializeSolverSchemes()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::InitializeSolverSchemes");
  InitializeWGSSolvers();

  ags_solver_ = std::make_shared<AGSLinearSolver>(*this, wgs_solvers_);
  if (groupsets_.size() == 1)
  {
    ags_solver_->SetMaxIterations(1);
    ags_solver_->SetVerbosity(false);
  }
  else
  {
    ags_solver_->SetMaxIterations(options_.max_ags_iterations);
    ags_solver_->SetVerbosity(options_.verbose_ags_iterations);
  }
  ags_solver_->SetTolerance(options_.ags_tolerance);
}

#ifndef __OPENSN_WITH_GPU__
void
LBSProblem::InitializeGPUExtras()
{
}

void
LBSProblem::ResetGPUCarriers()
{
}

void
LBSProblem::CheckCapableDevices()
{
}
#endif // __OPENSN_WITH_GPU__

std::vector<double>
LBSProblem::MakeSourceMomentsFromPhi()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::MakeSourceMomentsFromPhi");

  size_t num_local_dofs = discretization_->GetNumLocalDOFs(flux_moments_uk_man_);

  std::vector<double> source_moments(num_local_dofs, 0.0);
  for (auto& groupset : groupsets_)
  {
    active_set_source_function_(groupset,
                                source_moments,
                                phi_new_local_,
                                APPLY_AGS_SCATTER_SOURCES | APPLY_WGS_SCATTER_SOURCES |
                                  APPLY_AGS_FISSION_SOURCES | APPLY_WGS_FISSION_SOURCES);
  }

  return source_moments;
}

void
LBSProblem::UpdateFieldFunctions()
{
  CALI_CXX_MARK_SCOPE("LBSProblem::UpdateFieldFunctions");

  const auto& sdm = *discretization_;
  const auto& phi_uk_man = flux_moments_uk_man_;

  // Update flux moments
  for (const auto& [g_and_m, ff_index] : phi_field_functions_local_map_)
  {
    const auto g = g_and_m.first;
    const auto m = g_and_m.second;

    std::vector<double> data_vector_local(local_node_count_, 0.0);

    for (const auto& cell : grid_->local_cells)
    {
      const auto& cell_mapping = sdm.GetCellMapping(cell);
      const size_t num_nodes = cell_mapping.GetNumNodes();

      for (size_t i = 0; i < num_nodes; ++i)
      {
        const auto imapA = sdm.MapDOFLocal(cell, i, phi_uk_man, m, g);
        const auto imapB = sdm.MapDOFLocal(cell, i);

        data_vector_local[imapB] = phi_new_local_[imapA];
      } // for node
    } // for cell

    auto& ff_ptr = field_functions_.at(ff_index);
    ff_ptr->UpdateFieldVector(data_vector_local);
  }

  // Update power generation and scalar flux
  if (options_.power_field_function_on)
  {
    std::vector<double> data_vector_power_local(local_node_count_, 0.0);

    double local_total_power = 0.0;
    for (const auto& cell : grid_->local_cells)
    {
      const auto& cell_mapping = sdm.GetCellMapping(cell);
      const size_t num_nodes = cell_mapping.GetNumNodes();

      const auto& Vi = unit_cell_matrices_[cell.local_id].intV_shapeI;

      const auto& xs = block_id_to_xs_map_.at(cell.block_id);

      if (not xs->IsFissionable())
        continue;

      for (size_t i = 0; i < num_nodes; ++i)
      {
        const auto imapA = sdm.MapDOFLocal(cell, i);
        const auto imapB = sdm.MapDOFLocal(cell, i, phi_uk_man, 0, 0);

        double nodal_power = 0.0;
        for (unsigned int g = 0; g < num_groups_; ++g)
        {
          const double sigma_fg = xs->GetSigmaFission()[g];
          // const double kappa_g = xs->Kappa()[g];
          const double kappa_g = options_.power_default_kappa;

          nodal_power += kappa_g * sigma_fg * phi_new_local_[imapB + g];
        } // for g

        data_vector_power_local[imapA] = nodal_power;
        local_total_power += nodal_power * Vi(i);
      } // for node
    } // for cell

    double scale_factor = 1.0;
    if (options_.power_normalization > 0.0)
    {
      double global_total_power = 0.0;
      mpi_comm.all_reduce(local_total_power, global_total_power, mpi::op::sum<double>());
      scale_factor = options_.power_normalization / global_total_power;
      Scale(data_vector_power_local, scale_factor);
    }

    const size_t ff_index = power_gen_fieldfunc_local_handle_;

    auto& ff_ptr = field_functions_.at(ff_index);
    ff_ptr->UpdateFieldVector(data_vector_power_local);

    // scale scalar flux if neccessary
    if (scale_factor != 1.0)
    {
      for (unsigned int g = 0; g < num_groups_; ++g)
      {
        const size_t phi_ff_index = phi_field_functions_local_map_.at({g, size_t{0}});
        auto& phi_ff_ptr = field_functions_.at(phi_ff_index);
        const auto& phi_vec = phi_ff_ptr->GetLocalFieldVector();
        std::vector<double> phi_scaled(phi_vec.begin(), phi_vec.end());
        Scale(phi_scaled, scale_factor);
        phi_ff_ptr->UpdateFieldVector(phi_scaled);
      }
    }
  } // if power enabled
}

void
LBSProblem::SetPhiFromFieldFunctions(PhiSTLOption which_phi,
                                     const std::vector<unsigned int>& m_indices,
                                     const std::vector<unsigned int>& g_indices)
{
  CALI_CXX_MARK_SCOPE("LBSProblem::SetPhiFromFieldFunctions");

  std::vector<unsigned int> m_ids_to_copy = m_indices;
  std::vector<unsigned int> g_ids_to_copy = g_indices;
  if (m_indices.empty())
    for (unsigned int m = 0; m < num_moments_; ++m)
      m_ids_to_copy.push_back(m);
  if (g_ids_to_copy.empty())
    for (unsigned int g = 0; g < num_groups_; ++g)
      g_ids_to_copy.push_back(g);

  const auto& sdm = *discretization_;
  const auto& phi_uk_man = flux_moments_uk_man_;

  for (const auto m : m_ids_to_copy)
  {
    for (const auto g : g_ids_to_copy)
    {
      const size_t ff_index = phi_field_functions_local_map_.at({g, m});
      const auto& ff_ptr = field_functions_.at(ff_index);
      const auto& ff_data = ff_ptr->GetLocalFieldVector();

      for (const auto& cell : grid_->local_cells)
      {
        const auto& cell_mapping = sdm.GetCellMapping(cell);
        const size_t num_nodes = cell_mapping.GetNumNodes();

        for (size_t i = 0; i < num_nodes; ++i)
        {
          const auto imapA = sdm.MapDOFLocal(cell, i);
          const auto imapB = sdm.MapDOFLocal(cell, i, phi_uk_man, m, g);

          if (which_phi == PhiSTLOption::PHI_OLD)
            phi_old_local_[imapB] = ff_data[imapA];
          else if (which_phi == PhiSTLOption::PHI_NEW)
            phi_new_local_[imapB] = ff_data[imapA];
        } // for node
      } // for cell
    } // for g
  } // for m
}

LBSProblem::~LBSProblem()
{
  ResetGPUCarriers();
}

void
LBSProblem::SetSaveAngularFlux(bool save)
{
  options_.save_angular_flux = save;
  if (initialized_)
    applied_save_angular_flux_ = save;
}

void
LBSProblem::ZeroPhi()
{
  phi_old_local_.assign(phi_old_local_.size(), 0.0);
  phi_new_local_.assign(phi_new_local_.size(), 0.0);
}

void
LBSProblem::SetAdjoint(bool adjoint)
{
  OpenSnLogicalErrorIf(
    not initialized_, GetName() + ": Problem must be fully constructed before calling SetAdjoint.");

  if (adjoint)
    if (const auto* do_problem = dynamic_cast<const DiscreteOrdinatesProblem*>(this);
        do_problem and do_problem->IsTimeDependent())
      throw std::runtime_error(GetName() + ": Time-dependent adjoint problems are not supported.");

  options_.adjoint = adjoint;

  if (adjoint != applied_adjoint_)
  {
    // Reinitialize materials to obtain the proper forward/adjoint cross sections.
    InitializeMaterials();

    // Forward and adjoint sources are fundamentally different.
    point_sources_.clear();
    volumetric_sources_.clear();
    ClearBoundaries();

    // Reset all solution vectors.
    phi_old_local_.assign(phi_old_local_.size(), 0.0);
    phi_new_local_.assign(phi_new_local_.size(), 0.0);
    ZeroPsi();
    precursor_new_local_.assign(precursor_new_local_.size(), 0.0);

    applied_adjoint_ = adjoint;
  }
}

bool
LBSProblem::IsAdjoint() const
{
  return options_.adjoint;
}

} // namespace opensn

Open-Sn / opensn / 22654533986

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