diffusion_PWLC_02c_assembleAand_b.cc

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#include "diffusion_PWLC.h"
 
#include "mesh/MeshContinuum/chi_meshcontinuum.h"
#include "math/SpatialDiscretization/SpatialDiscretization.h"
 
#include "A_LBSSolver/lbs_structs.h"
 
#include "chi_runtime.h"
#include "chi_log.h"
#include "utils/chi_timer.h"
 
#define DefaultBCDirichlet                                                     \
  BoundaryCondition                                                            \
  {                                                                            \
    BCType::DIRICHLET, { 0, 0, 0 }                                             \
  }
 
namespace lbs::acceleration
{
// ###################################################################
/**Assembles both the matrix and the RHS using unit cell-matrices. These are
 * the routines used in the production versions.*/
void DiffusionPWLCSolver::AssembleAand_b(const std::vector<double>& q_vector)
{
  const size_t num_local_dofs = sdm_.GetNumLocalAndGhostDOFs(uk_man_);
  ChiInvalidArgumentIf(q_vector.size() != num_local_dofs,
                       std::string("q_vector size mismatch. ") +
                         std::to_string(q_vector.size()) + " vs " +
                         std::to_string(num_local_dofs));
 
  const std::string fname = "lbs::acceleration::DiffusionMIPSolver::"
                            "AssembleAand_b";
  if (A_ == nullptr or rhs_ == nullptr or ksp_ == nullptr)
    throw std::logic_error(fname + ": Some or all PETSc elements are null. "
                                   "Check that Initialize has been called.");
  if (options.verbose)
    Chi::log.Log() << Chi::program_timer.GetTimeString()
                   << " Starting assembly";
 
  const size_t num_groups = uk_man_.unknowns_.front().num_components_;
 
  VecSet(rhs_, 0.0);
  for (const auto& cell : grid_.local_cells)
  {
    const size_t num_faces = cell.faces_.size();
    const auto& cell_mapping = sdm_.GetCellMapping(cell);
    const size_t num_nodes = cell_mapping.NumNodes();
    const auto cc_nodes = cell_mapping.GetNodeLocations();
    const auto& unit_cell_matrices = unit_cell_matrices_[cell.local_id_];
 
    const auto& cell_K_matrix = unit_cell_matrices.K_matrix;
    const auto& cell_M_matrix = unit_cell_matrices.M_matrix;
    const auto& cell_Vi = unit_cell_matrices.Vi_vectors;
 
    const auto& xs = mat_id_2_xs_map_.at(cell.material_id_);
 
    //=========================================== Mark dirichlet nodes
    typedef std::pair<bool, double> DirichFlagVal;
    std::vector<DirichFlagVal> node_is_dirichlet(num_nodes, {false, 0.0});
    for (size_t f = 0; f < num_faces; ++f)
    {
      const auto& face = cell.faces_[f];
      if (not face.has_neighbor_)
      {
        auto bc = DefaultBCDirichlet;
        if (bcs_.count(face.neighbor_id_) > 0) bc = bcs_.at(face.neighbor_id_);
 
        if (bc.type != BCType::DIRICHLET) continue;
 
        const size_t num_face_nodes = cell_mapping.NumFaceNodes(f);
        for (size_t fi = 0; fi < num_face_nodes; ++fi)
          node_is_dirichlet[cell_mapping.MapFaceNode(f, fi)] = {true,
                                                                bc.values[0]};
      }
    }
 
    for (size_t g = 0; g < num_groups; ++g)
    {
      //==================================== Get coefficient and nodal src
      const double Dg = xs.Dg[g];
      const double sigr_g = xs.sigR[g];
 
      std::vector<double> qg(num_nodes, 0.0);
      for (size_t j = 0; j < num_nodes; j++)
        qg[j] = q_vector[sdm_.MapDOFLocal(cell, j, uk_man_, 0, g)];
 
      //==================================== Assemble continuous terms
      for (size_t i = 0; i < num_nodes; i++)
      {
        if (node_is_dirichlet[i].first) continue;
        const int64_t imap = sdm_.MapDOF(cell, i, uk_man_, 0, g);
        double entry_rhs_i = 0.0;
        for (size_t j = 0; j < num_nodes; j++)
        {
          const int64_t jmap = sdm_.MapDOF(cell, j, uk_man_, 0, g);
 
          const double entry_aij =
            Dg * cell_K_matrix[i][j] + sigr_g * cell_M_matrix[i][j];
 
          if (not node_is_dirichlet[j].first)
            MatSetValue(A_, imap, jmap, entry_aij, ADD_VALUES);
          else
          {
            const double bcvalue = node_is_dirichlet[j].second;
            VecSetValue(rhs_, imap, -entry_aij * bcvalue, ADD_VALUES);
          }
 
          entry_rhs_i += qg[j] * cell_M_matrix[i][j];
        } // for j
 
        VecSetValue(rhs_, imap, entry_rhs_i, ADD_VALUES);
      } // for i
 
      //==================================== Assemble face terms
      for (size_t f = 0; f < num_faces; ++f)
      {
        const auto& face = cell.faces_[f];
        const size_t num_face_nodes = cell_mapping.NumFaceNodes(f);
 
        const auto& face_M = unit_cell_matrices.face_M_matrices[f];
        const auto& face_Si = unit_cell_matrices.face_Si_vectors[f];
 
        if (not face.has_neighbor_)
        {
          auto bc = DefaultBCDirichlet;
          if (bcs_.count(face.neighbor_id_) > 0)
            bc = bcs_.at(face.neighbor_id_);
 
          if (bc.type == BCType::DIRICHLET)
          {
            const double bc_value = bc.values[0];
 
            for (size_t fi = 0; fi < num_face_nodes; ++fi)
            {
              const int i = cell_mapping.MapFaceNode(f, fi);
              const int64_t imap = sdm_.MapDOF(cell, i, uk_man_, 0, g);
 
              // MatSetValue(A_, imap, imap, cell_Vi[i], ADD_VALUES);
              // VecSetValue(rhs_, imap, bc_value * cell_Vi[i], ADD_VALUES);
              MatSetValue(A_, imap, imap, 1.0, ADD_VALUES);
              VecSetValue(rhs_, imap, bc_value, ADD_VALUES);
            } // for fi
 
          } // Dirichlet BC
          else if (bc.type == BCType::ROBIN)
          {
            const double aval = bc.values[0];
            const double bval = bc.values[1];
            const double fval = bc.values[2];
 
            if (std::fabs(bval) < 1.0e-12) continue; // a and f assumed zero
 
            for (size_t fi = 0; fi < num_face_nodes; fi++)
            {
              const int i = cell_mapping.MapFaceNode(f, fi);
              const int64_t ir = sdm_.MapDOF(cell, i, uk_man_, 0, g);
 
              if (std::fabs(aval) >= 1.0e-12)
              {
                for (size_t fj = 0; fj < num_face_nodes; fj++)
                {
                  const int j = cell_mapping.MapFaceNode(f, fj);
                  const int64_t jr = sdm_.MapDOF(cell, j, uk_man_, 0, g);
 
                  const double aij = (aval / bval) * face_M[i][j];
 
                  MatSetValue(A_, ir, jr, aij, ADD_VALUES);
                } // for fj
              }   // if a nonzero
 
              if (std::fabs(fval) >= 1.0e-12)
              {
                const double rhs_val = (fval / bval) * face_Si[i];
 
                VecSetValue(rhs_, ir, rhs_val, ADD_VALUES);
              } // if f nonzero
            }   // for fi
          }     // Robin BC
        }       // boundary face
      }         // for face
    }           // for g
  }             // for cell
 
  MatAssemblyBegin(A_, MAT_FINAL_ASSEMBLY);
  MatAssemblyEnd(A_, MAT_FINAL_ASSEMBLY);
  VecAssemblyBegin(rhs_);
  VecAssemblyEnd(rhs_);
 
  if (options.verbose)
  {
    MatInfo info;
    MatGetInfo(A_, MAT_GLOBAL_SUM, &info);
 
    Chi::log.Log() << "Number of mallocs used = " << info.mallocs
                   << "\nNumber of non-zeros allocated = " << info.nz_allocated
                   << "\nNumber of non-zeros used = " << info.nz_used
                   << "\nNumber of unneeded non-zeros = " << info.nz_unneeded;
  }
 
  if (options.perform_symmetry_check)
  {
    PetscBool symmetry = PETSC_FALSE;
    MatIsSymmetric(A_, 1.0e-6, &symmetry);
    if (symmetry == PETSC_FALSE)
      throw std::logic_error(fname + ":Symmetry check failed");
  }
 
  KSPSetOperators(ksp_, A_, A_);
 
  if (options.verbose)
    Chi::log.Log() << Chi::program_timer.GetTimeString()
                   << " Assembly completed";
 
  PC pc;
  KSPGetPC(ksp_, &pc);
  PCSetUp(pc);
 
  KSPSetUp(ksp_);
}
 
} // namespace lbs::acceleration