poisson_3d_homogeneous.hpp

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/**
 * @file poisson_3d_homogeneous.hpp
 * @example poisson_3d_homogeneous.hpp
 * @brief Operator for 3D poisson problem example
 * @date 2023-01-31
 * 
 * @copyright Copyright (c) 2023
 * 
 */
 
#ifndef __POISSON3DHOMOGENEOUS_HPP__
#define __POISSON3DHOMOGENEOUS_HPP__
 
#include <stdlib.h>
#include <BasicFiniteElements.hpp>
 
using VolEle = MoFEM::VolumeElementForcesAndSourcesCore;
 
using OpVolEle = MoFEM::VolumeElementForcesAndSourcesCore::UserDataOperator;
 
using EntData = EntitiesFieldData::EntData;
 
namespace Poisson3DHomogeneousOperators {
 
FTensor::Index<'i', 3> i;
 
const double body_source = 1.;
 
struct OpDomainLhsMatrixK : public OpVolEle {
public:
  OpDomainLhsMatrixK(std::string row_field_name, std::string col_field_name)
      : OpVolEle(row_field_name, col_field_name, OpVolEle::OPROWCOL) {
    sYmm = true;
  }
 
  MoFEMErrorCode doWork(int row_side, int col_side, EntityType row_type,
                        EntityType col_type, EntData &row_data,
                        EntData &col_data) {
    MoFEMFunctionBegin;
 
    const int nb_row_dofs = row_data.getIndices().size();
    const int nb_col_dofs = col_data.getIndices().size();
 
    if (nb_row_dofs && nb_col_dofs) {
 
      locLhs.resize(nb_row_dofs, nb_col_dofs, false);
      locLhs.clear();
 
      // get element volume
      const double volume = getMeasure();
 
      // get number of integration points
      const int nb_integration_points = getGaussPts().size2();
      // get integration weights
      auto t_w = getFTensor0IntegrationWeight();
 
      // get derivatives of base functions on row
      auto t_row_diff_base = row_data.getFTensor1DiffN<3>();
 
      // START THE LOOP OVER INTEGRATION POINTS TO CALCULATE LOCAL MATRIX
      for (int gg = 0; gg != nb_integration_points; gg++) {
        const double a = t_w * volume;
 
        for (int rr = 0; rr != nb_row_dofs; ++rr) {
          // get derivatives of base functions on column
          auto t_col_diff_base = col_data.getFTensor1DiffN<3>(gg, 0);
 
          for (int cc = 0; cc != nb_col_dofs; cc++) {
            locLhs(rr, cc) += t_row_diff_base(i) * t_col_diff_base(i) * a;
 
            // move to the derivatives of the next base functions on column
            ++t_col_diff_base;
          }
 
          // move to the derivatives of the next base functions on row
          ++t_row_diff_base;
        }
 
        // move to the weight of the next integration point
        ++t_w;
      }
 
      // FILL VALUES OF LOCAL MATRIX ENTRIES TO THE GLOBAL MATRIX
      CHKERR MatSetValues(getKSPB(), row_data, col_data, &locLhs(0, 0),
                          ADD_VALUES);
      if (row_side != col_side || row_type != col_type) {
        transLocLhs.resize(nb_col_dofs, nb_row_dofs, false);
        noalias(transLocLhs) = trans(locLhs);
        CHKERR MatSetValues(getKSPB(), col_data, row_data, &transLocLhs(0, 0),
                            ADD_VALUES);
      }
    }
 
    MoFEMFunctionReturn(0);
  }
 
private:
  MatrixDouble locLhs, transLocLhs;
};
 
struct OpDomainRhsVectorF : public OpVolEle {
public:
  OpDomainRhsVectorF(std::string field_name)
      : OpVolEle(field_name, OpVolEle::OPROW) {}
 
  MoFEMErrorCode doWork(int side, EntityType type, EntData &data) {
    MoFEMFunctionBegin;
 
    const int nb_dofs = data.getIndices().size();
 
    if (nb_dofs) {
      locRhs.resize(nb_dofs, false);
      locRhs.clear();
 
      // get element volume
      const double volume = getMeasure();
 
      // get number of integration points
      const int nb_integration_points = getGaussPts().size2();
      // get integration weights
      auto t_w = getFTensor0IntegrationWeight();
 
      // get base function
      auto t_base = data.getFTensor0N();
 
      // START THE LOOP OVER INTEGRATION POINTS TO CALCULATE LOCAL VECTOR
      for (int gg = 0; gg != nb_integration_points; gg++) {
        const double a = t_w * volume;
 
        for (int rr = 0; rr != nb_dofs; rr++) {
          locRhs[rr] += t_base * body_source * a;
 
          // move to the next base function
          ++t_base;
        }
 
        // move to the weight of the next integration point
        ++t_w;
      }
 
      // FILL VALUES OF LOCAL VECTOR ENTRIES TO THE GLOBAL VECTOR
 
      // Ignoring DOFs on boundary (index -1)
      CHKERR VecSetOption(getKSPf(), VEC_IGNORE_NEGATIVE_INDICES, PETSC_TRUE);
      CHKERR VecSetValues(getKSPf(), data, &*locRhs.begin(), ADD_VALUES);
    }
 
    MoFEMFunctionReturn(0);
  }
 
private:
  VectorDouble locRhs;
};
 
}; // namespace Poisson3DHomogeneousOperators
 
#endif //__POISSON3DHOMOGENEOUS_HPP__