Auxiliary class to extract locations of nodes in MFEM GridFunctions and project values defined at them to set DoFs. More...

#include <MFEMNodalProjector.h>

Public Member Functions
	MFEMNodalProjector ()=default

void	extractNodePositions (const mfem::ParFiniteElementSpace &fespace, mfem::Vector &node_positions, mfem::Ordering::Type &node_ordering)
	Extract node positions from MFEM FESpace at which projection will take place.

void	projectNodalValues (const mfem::Vector &nodal_vals, const mfem::Ordering::Type &nodal_val_ordering, mfem::ParGridFunction &gridfunction)
	Project a vector of values provided at projection points (nodes) to set GridFunction DoFs.

Detailed Description

Auxiliary class to extract locations of nodes in MFEM GridFunctions and project values defined at them to set DoFs.

Definition at line 22 of file MFEMNodalProjector.h.

Constructor & Destructor Documentation

◆ MFEMNodalProjector()

MFEMNodalProjector::MFEMNodalProjector ( )

default

Member Function Documentation

◆ extractNodePositions()

void MFEMNodalProjector::extractNodePositions	(	const mfem::ParFiniteElementSpace &	fespace,
		mfem::Vector &	node_positions,
		mfem::Ordering::Type &	node_ordering
	)

Extract node positions from MFEM FESpace at which projection will take place.

Definition at line 17 of file MFEMNodalProjector.C.

{
  const int nelem = fespace.GetParMesh()->GetNE();
  const int dim = fespace.GetParMesh()->Dimension();
 
  // Find total number of local nodes/interpolation points
  int nnodes = 0;
  for (const auto i : make_range(nelem))
    nnodes += fespace.GetFE(i)->GetNodes().GetNPoints();
 
  node_positions.SetSize(nnodes * dim);
 
  int nodal_offset = 0;
  for (const auto i : make_range(nelem))
  {
    const mfem::IntegrationRule ir = fespace.GetFE(i)->GetNodes();
    const int nqpt = ir.GetNPoints();
 
    mfem::DenseMatrix pos;
    fespace.GetElementTransformation(i)->Transform(ir, pos);
    mfem::Vector row;
 
    for (const auto d : make_range(dim))
    {
      row.SetDataAndSize(node_positions.GetData() + nodal_offset + d * nnodes, nqpt);
      pos.GetRow(d, row);
    }
 
    nodal_offset += nqpt;
  }
  node_ordering = mfem::Ordering::Type::byNODES;
}

Referenced by MultiApplibMeshToMFEMShapeEvaluationTransfer::transferVariables(), and MultiAppMFEMShapeEvaluationTransfer::transferVariables().

◆ projectNodalValues()

void MFEMNodalProjector::projectNodalValues	(	const mfem::Vector &	nodal_vals,
		const mfem::Ordering::Type &	nodal_val_ordering,
		mfem::ParGridFunction &	gridfunction
	)

Project a vector of values provided at projection points (nodes) to set GridFunction DoFs.

Definition at line 53 of file MFEMNodalProjector.C.

{
  mfem::ParFiniteElementSpace & fespace = *gridfunction.ParFESpace();
  const int nelem = fespace.GetParMesh()->GetNE();
  const int gf_ncomp = gridfunction.VectorDim();
 
  fespace.GetParMesh()->EnsureNodes();
 
  // Check FESpaces can be transferred
  const auto map = fespace.FEColl()->GetMapType(fespace.GetParMesh()->Dimension());
  const bool H1L2 = map == mfem::FiniteElement::VALUE || map == mfem::FiniteElement::INTEGRAL;
  const bool RTND = map == mfem::FiniteElement::H_DIV || map == mfem::FiniteElement::H_CURL;
  if (!H1L2 && !RTND)
    mooseError("FESpace type not supported yet in transfers.");
 
  // Project the interpolated values to the target FiniteElementSpace.
  mfem::Ordering::Type dof_ordering = H1L2 ? mfem::Ordering::byNODES : mfem::Ordering::byVDIM;
  mfem::Array<int> vdofs;
  mfem::Vector vals;
  int nodal_offset = 0;
  for (const auto el : make_range(nelem))
  {
    const int nqpt = fespace.GetFE(el)->GetNodes().GetNPoints();
    mfem::Vector dof_vals(nqpt * gf_ncomp);
    nodal_vals.HostRead();
    fespace.GetElementVDofs(el, vdofs); // Returned vdofs always indexed with ordering byNODES
    for (const auto qp : make_range(nqpt))
      for (const auto d : make_range(gf_ncomp))
        dof_vals(Moose::MFEM::MFEMIndex(d, qp, gf_ncomp, nqpt, dof_ordering)) = nodal_vals(
            Moose::MFEM::MFEMIndex(d, qp, gf_ncomp, nqpt, nodal_val_ordering) + nodal_offset);
 
    if (H1L2)
      gridfunction.SetSubVector(vdofs, dof_vals);
    else if (RTND)
    {
      vals.SetSize(vdofs.Size());
      fespace.GetFE(el)->ProjectFromNodes(dof_vals, *fespace.GetElementTransformation(el), vals);
      gridfunction.SetSubVector(vdofs, vals);
    }
 
    nodal_offset += nqpt * gf_ncomp;
  }
  gridfunction.SetTrueVector();
}