poisson_2d_homogeneous.cpp

Solution of poisson equation. Direct implementation of User Data Operators for teaching proposes.

Note

In practical application we suggest use form integrators to generalise and simplify code. However, here we like to expose user to ways how to implement data operator from scratch.

/**
 * \file poisson_2d_homogeneous.cpp
 * \example poisson_2d_homogeneous.cpp
 *
 * Solution of poisson equation. Direct implementation of User Data Operators
 * for teaching proposes.
 *
 * \note In practical application we suggest use form integrators to generalise
 * and simplify code. However, here we like to expose user to ways how to
 * implement data operator from scratch.
 */
 
constexpr auto field_name = "U";
 
constexpr int SPACE_DIM =
    EXECUTABLE_DIMENSION; //< Space dimension of problem, mesh
 
#include <poisson_2d_homogeneous.hpp>
 
using namespace MoFEM;
using namespace Poisson2DHomogeneousOperators;
 
using PostProcFaceEle = PostProcBrokenMeshInMoab<DomainEle>;
 
static char help[] = "...\n\n";
 
struct Poisson2DHomogeneous {
public:
  Poisson2DHomogeneous(MoFEM::Interface &m_field);
 
  // Declaration of the main function to run analysis
  MoFEMErrorCode runProgram();
 
private:
  // Declaration of other main functions called in runProgram()
  MoFEMErrorCode readMesh();
  MoFEMErrorCode setupProblem();
  MoFEMErrorCode boundaryCondition();
  MoFEMErrorCode assembleSystem();
  MoFEMErrorCode setIntegrationRules();
  MoFEMErrorCode solveSystem();
  MoFEMErrorCode outputResults();
 
  // MoFEM interfaces
  MoFEM::Interface &mField;
  Simple *simpleInterface;
 
  // Field name and approximation order
  int oRder;
};
 
Poisson2DHomogeneous::Poisson2DHomogeneous(MoFEM::Interface &m_field)
    : mField(m_field) {}
 
//! [Read mesh]
MoFEMErrorCode Poisson2DHomogeneous::readMesh() {
  MoFEMFunctionBegin;
 
  CHKERR mField.getInterface(simpleInterface);
  CHKERR simpleInterface->getOptions();
  CHKERR simpleInterface->loadFile();
 
  MoFEMFunctionReturn(0);
}
//! [Read mesh]
 
//! [Setup problem]
MoFEMErrorCode Poisson2DHomogeneous::setupProblem() {
  MoFEMFunctionBegin;
 
  CHKERR simpleInterface->addDomainField(field_name, H1,
                                         AINSWORTH_LEGENDRE_BASE, 1);
 
  int oRder = 3;
  CHKERR PetscOptionsGetInt(PETSC_NULL, "", "-order", &oRder, PETSC_NULL);
  CHKERR simpleInterface->setFieldOrder(field_name, oRder);
 
  CHKERR simpleInterface->setUp();
 
  MoFEMFunctionReturn(0);
}
//! [Setup problem]
 
//! [Boundary condition]
MoFEMErrorCode Poisson2DHomogeneous::boundaryCondition() {
  MoFEMFunctionBegin;
 
  auto bc_mng = mField.getInterface<BcManager>();
 
  // Remove BCs from blockset name "BOUNDARY_CONDITION" or SETU, note that you
  // can use regular expression to put list of blocksets;
  CHKERR bc_mng->removeBlockDOFsOnEntities<BcScalarMeshsetType<BLOCKSET>>(
      simpleInterface->getProblemName(), "(BOUNDARY_CONDITION|SETU)",
      std::string(field_name), true);
 
  MoFEMFunctionReturn(0);
}
//! [Boundary condition]
 
//! [Assemble system]
MoFEMErrorCode Poisson2DHomogeneous::assembleSystem() {
  MoFEMFunctionBegin;
 
  auto pipeline_mng = mField.getInterface<PipelineManager>();
 
  { // Push operators to the Pipeline that is responsible for calculating LHS
    CHKERR AddHOOps<SPACE_DIM, SPACE_DIM, SPACE_DIM>::add(
        pipeline_mng->getOpDomainLhsPipeline(), {H1});
    pipeline_mng->getOpDomainLhsPipeline().push_back(
        new OpDomainLhsMatrixK(field_name, field_name));
  }
 
  { // Push operators to the Pipeline that is responsible for calculating RHS
 
    auto set_values_to_bc_dofs = [&](auto &fe) {
      auto get_bc_hook = [&]() {
        EssentialPreProc<TemperatureCubitBcData> hook(mField, fe, {});
        return hook;
      };
      fe->preProcessHook = get_bc_hook();
    };
 
    // you can skip that if boundary condition is prescribing zero
    auto calculate_residual_from_set_values_on_bc = [&](auto &pipeline) {
      using DomainEle =
          PipelineManager::ElementsAndOpsByDim<SPACE_DIM>::DomainEle;
      using DomainEleOp = DomainEle::UserDataOperator;
      using OpInternal = FormsIntegrators<DomainEleOp>::Assembly<
          PETSC>::LinearForm<GAUSS>::OpGradTimesTensor<1, 1, SPACE_DIM>;
 
      auto grad_u_vals_ptr = boost::make_shared<MatrixDouble>();
      pipeline_mng->getOpDomainRhsPipeline().push_back(
          new OpCalculateScalarFieldGradient<SPACE_DIM>(field_name,
                                                        grad_u_vals_ptr));
      pipeline_mng->getOpDomainRhsPipeline().push_back(
          new OpInternal(field_name, grad_u_vals_ptr,
                         [](double, double, double) constexpr { return -1; }));
    };
 
    CHKERR AddHOOps<SPACE_DIM, SPACE_DIM, SPACE_DIM>::add(
        pipeline_mng->getOpDomainRhsPipeline(), {H1});
    set_values_to_bc_dofs(pipeline_mng->getDomainRhsFE());
    calculate_residual_from_set_values_on_bc(
        pipeline_mng->getOpDomainRhsPipeline());
    pipeline_mng->getOpDomainRhsPipeline().push_back(
        new OpDomainRhsVectorF(field_name));
  }
 
  MoFEMFunctionReturn(0);
}
//! [Assemble system]
 
//! [Set integration rules]
MoFEMErrorCode Poisson2DHomogeneous::setIntegrationRules() {
  MoFEMFunctionBegin;
 
  auto rule_lhs = [](int, int, int p) -> int { return 2 * (p - 1); };
  auto rule_rhs = [](int, int, int p) -> int { return p; };
 
  auto pipeline_mng = mField.getInterface<PipelineManager>();
  CHKERR pipeline_mng->setDomainLhsIntegrationRule(rule_lhs);
  CHKERR pipeline_mng->setDomainRhsIntegrationRule(rule_rhs);
 
  MoFEMFunctionReturn(0);
}
//! [Set integration rules]
 
//! [Solve system]
MoFEMErrorCode Poisson2DHomogeneous::solveSystem() {
  MoFEMFunctionBegin;
 
  auto pipeline_mng = mField.getInterface<PipelineManager>();
 
  auto ksp_solver = pipeline_mng->createKSP();
  CHKERR KSPSetFromOptions(ksp_solver);
  CHKERR KSPSetUp(ksp_solver);
 
  // Create RHS and solution vectors
  auto dm = simpleInterface->getDM();
  auto F = createDMVector(dm);
  auto D = vectorDuplicate(F);
 
  // Solve the system
  CHKERR KSPSolve(ksp_solver, F, D);
 
  // Scatter result data on the mesh
  CHKERR VecGhostUpdateBegin(D, INSERT_VALUES, SCATTER_FORWARD);
  CHKERR VecGhostUpdateEnd(D, INSERT_VALUES, SCATTER_FORWARD);
  CHKERR DMoFEMMeshToLocalVector(dm, D, INSERT_VALUES, SCATTER_REVERSE);
 
  MoFEMFunctionReturn(0);
}
//! [Solve system]
 
//! [Output results]
MoFEMErrorCode Poisson2DHomogeneous::outputResults() {
  MoFEMFunctionBegin;
 
  auto pipeline_mng = mField.getInterface<PipelineManager>();
  pipeline_mng->getDomainLhsFE().reset();
 
  auto post_proc_fe = boost::make_shared<PostProcFaceEle>(mField);
  CHKERR AddHOOps<SPACE_DIM, SPACE_DIM, SPACE_DIM>::add(
    post_proc_fe->getOpPtrVector(), {H1});
 
  auto u_ptr = boost::make_shared<VectorDouble>();
  auto grad_u_ptr = boost::make_shared<MatrixDouble>();
  post_proc_fe->getOpPtrVector().push_back(
      new OpCalculateScalarFieldValues(field_name, u_ptr));
 
  post_proc_fe->getOpPtrVector().push_back(
      new OpCalculateScalarFieldGradient<SPACE_DIM>(field_name, grad_u_ptr));
 
  using OpPPMap = OpPostProcMapInMoab<SPACE_DIM, SPACE_DIM>;
 
  post_proc_fe->getOpPtrVector().push_back(
 
      new OpPPMap(post_proc_fe->getPostProcMesh(),
                  post_proc_fe->getMapGaussPts(),
 
                  OpPPMap::DataMapVec{{"U", u_ptr}},
 
                  OpPPMap::DataMapMat{{"GRAD_U", grad_u_ptr}},
 
                  OpPPMap::DataMapMat{},
 
                  OpPPMap::DataMapMat{}
 
                  )
 
  );
 
  pipeline_mng->getDomainRhsFE() = post_proc_fe;
  CHKERR pipeline_mng->loopFiniteElements();
  CHKERR post_proc_fe->writeFile("out_result.h5m");
 
  MoFEMFunctionReturn(0);
}
//! [Output results]
 
//! [Run program]
MoFEMErrorCode Poisson2DHomogeneous::runProgram() {
  MoFEMFunctionBegin;
 
  CHKERR readMesh();
  CHKERR setupProblem();
  CHKERR boundaryCondition();
  CHKERR setIntegrationRules();
  CHKERR assembleSystem();
  CHKERR solveSystem();
  CHKERR outputResults();
 
  MoFEMFunctionReturn(0);
}
//! [Run program]
 
//! [Main]
int main(int argc, char *argv[]) {
 
  // Initialisation of MoFEM/PETSc and MOAB data structures
  const char param_file[] = "param_file.petsc";
  MoFEM::Core::Initialize(&argc, &argv, param_file, help);
 
  // Error handling
  try {
    // Register MoFEM discrete manager in PETSc
    DMType dm_name = "DMMOFEM";
    CHKERR DMRegister_MoFEM(dm_name);
 
    // Create MOAB instance
    moab::Core mb_instance;              // mesh database
    moab::Interface &moab = mb_instance; // mesh database interface
 
    // Create MoFEM instance
    MoFEM::Core core(moab);           // finite element database
    MoFEM::Interface &m_field = core; // finite element interface
 
    // Run the main analysis
    Poisson2DHomogeneous poisson_problem(m_field);
    CHKERR poisson_problem.runProgram();
  }
  CATCH_ERRORS;
 
  // Finish work: cleaning memory, getting statistics, etc.
  MoFEM::Core::Finalize();
 
  return 0;
}
//! [Main]