meshfunction_solution_transfer.C

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 
 
#include "libmesh/meshfunction_solution_transfer.h"
 
#include "libmesh/system.h"
#include "libmesh/numeric_vector.h"
#include "libmesh/mesh_function.h"
#include "libmesh/node.h"
#include "libmesh/variable.h"
 
namespace libMesh
{
 
MeshFunctionSolutionTransfer::MeshFunctionSolutionTransfer(const libMesh::Parallel::Communicator & comm_in) :
  SolutionTransfer(comm_in)
{}
 
MeshFunctionSolutionTransfer::~MeshFunctionSolutionTransfer() = default;
 
void
MeshFunctionSolutionTransfer::transfer(const Variable & from_var,
                                       const Variable & to_var)
{
  // This only works when transferring to a Lagrange variable
  libmesh_assert(to_var.type().family == LAGRANGE);
 
  unsigned int to_var_num = to_var.number();
 
  System * from_sys = from_var.system();
  System * to_sys = to_var.system();
 
  // Only works with a serialized mesh to transfer from!
  libmesh_assert(from_sys->get_mesh().is_serial());
 
  unsigned int to_sys_num = to_sys->number();
 
  EquationSystems & from_es = from_sys->get_equation_systems();
 
  //Create a serialized version of the solution vector
  std::unique_ptr<NumericVector<Number>> serialized_solution = NumericVector<Number>::build(from_sys->get_mesh().comm());
  serialized_solution->init(from_sys->n_dofs(), false, SERIAL);
 
  // Need to pull down a full copy of this vector on every processor
  // so we can get values in parallel
  from_sys->solution->localize(*serialized_solution);
 
  MeshFunction from_func(from_es, *serialized_solution, from_sys->get_dof_map(), to_var_num);
  from_func.init();
 
  // Now loop over the nodes of the 'To' mesh setting values for each variable.
  for (const auto & node : to_sys->get_mesh().local_node_ptr_range())
    to_sys->solution->set(node->dof_number(to_sys_num, to_var_num, 0), from_func(*node)); // 0 is for the value component
 
  to_sys->solution->close();
  to_sys->update();
}
 
} // namespace libMesh