boundary_condition.cpp

// Copyright (c) Lawrence Livermore National Security, LLC and
// other Serac Project Developers. See the top-level LICENSE file for
// details.
//
// SPDX-License-Identifier: (BSD-3-Clause)
 
#include <algorithm>
#include <memory>
 
#include "serac/physics/boundary_conditions/boundary_condition.hpp"
#include "serac/infrastructure/variant.hpp"
#include "serac/physics/state/finite_element_state.hpp"
 
namespace serac {
 
BoundaryCondition::BoundaryCondition(GeneralCoefficient coef, const std::optional<int> component,
                                     const mfem::ParFiniteElementSpace& space, const std::set<int>& attrs)
    : coef_(coef), component_(component), attr_markers_(space.GetMesh()->bdr_attributes.Max()), space_(space)
{
  if (get_if<std::shared_ptr<mfem::VectorCoefficient>>(&coef_)) {
    SLIC_ERROR_ROOT_IF(component_, "A vector coefficient must be applied to all components");
  }
 
  attr_markers_ = 0;
 
  for (const int attr : attrs) {
    SLIC_ASSERT_MSG(attr <= attr_markers_.Size(), "Attribute specified larger than what is found in the mesh.");
    attr_markers_[attr - 1] = 1;
  }
 
  setDofListsFromAttributeMarkers();
}
 
BoundaryCondition::BoundaryCondition(GeneralCoefficient coef, const std::optional<int> component,
                                     const mfem::ParFiniteElementSpace& space, const mfem::Array<int>& true_dofs)
    : coef_(coef), component_(component), attr_markers_(0), space_(space)
{
  if (get_if<std::shared_ptr<mfem::VectorCoefficient>>(&coef_)) {
    SLIC_ERROR_IF(component_, "A vector coefficient must be applied to all components");
  }
  setTrueDofList(true_dofs);
}
 
void BoundaryCondition::setTrueDofList(const mfem::Array<int>& true_dofs)
{
  true_dofs_ = true_dofs;
 
  // Create a marker arrays for the true and local dofs
  mfem::Array<int> true_dof_marker(space_.GetTrueVSize());
  mfem::Array<int> local_dof_marker(space_.GetVSize());
 
  mfem::FiniteElementSpace::ListToMarker(true_dofs_, space_.GetTrueVSize(), true_dof_marker);
 
  space_.GetRestrictionMatrix()->BooleanMultTranspose(true_dof_marker, local_dof_marker);
 
  mfem::FiniteElementSpace::MarkerToList(local_dof_marker, local_dofs_);
}
 
void BoundaryCondition::setDofListsFromAttributeMarkers()
{
  auto& mutable_space = const_cast<mfem::ParFiniteElementSpace&>(space_);
 
  if (component_) {
    mfem::Array<int> dof_markers;
 
    mutable_space.GetEssentialTrueDofs(attr_markers_, true_dofs_, *component_);
    space_.GetEssentialVDofs(attr_markers_, dof_markers, *component_);
 
    // The VDof call actually returns a marker array, so we need to transform it to a list of indices
    space_.MarkerToList(dof_markers, local_dofs_);
 
  } else {
    mfem::Array<int> dof_markers;
 
    mutable_space.GetEssentialTrueDofs(attr_markers_, true_dofs_);
    space_.GetEssentialVDofs(attr_markers_, dof_markers);
 
    // The VDof call actually returns a marker array, so we need to transform it to a list of indices
    space_.MarkerToList(dof_markers, local_dofs_);
  }
}
 
void BoundaryCondition::setDofs(mfem::Vector& vector, const double time) const
{
  SLIC_ERROR_IF(space_.GetTrueVSize() != vector.Size(),
                "State to project and boundary condition space are not compatible.");
 
  FiniteElementState state(space_);
 
  // Generate the scalar dof list from the vector dof list
  mfem::Array<int> dof_list(local_dofs_.Size());
  std::transform(local_dofs_.begin(), local_dofs_.end(), dof_list.begin(),
                 [&space = space_](int ldof) { return space.VDofToDof(ldof); });
 
  // the only reason to store a VectorCoefficient is to act on all components
  if (is_vector_valued(coef_)) {
    auto vec_coef = get<std::shared_ptr<mfem::VectorCoefficient>>(coef_);
    vec_coef->SetTime(time);
    state.project(*vec_coef, dof_list);
  } else {
    // an mfem::Coefficient could be used to describe a scalar-valued function, or
    // a single component of a vector-valued function
    auto scalar_coef = get<std::shared_ptr<mfem::Coefficient>>(coef_);
    scalar_coef->SetTime(time);
    if (component_) {
      state.project(*scalar_coef, dof_list, *component_);
 
    } else {
      state.projectOnBoundary(*scalar_coef, attr_markers_);
    }
  }
 
  for (int i : true_dofs_) {
    vector(i) = state(i);
  }
}
 
void BoundaryCondition::apply(mfem::HypreParMatrix& k_mat, mfem::Vector& rhs, mfem::Vector& state) const
{
  std::unique_ptr<mfem::HypreParMatrix> eliminated_entries(k_mat.EliminateRowsCols(true_dofs_));
  mfem::EliminateBC(k_mat, *eliminated_entries, true_dofs_, state, rhs);
}
 
}  // namespace serac