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mfem/examples/moonolith/ex1p.cpp
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// MFEM + Moonolith Example 1 (parallel version)
//
// Compile with: make ex1p
//
// Moonolith sample runs:
// mpirun -np 4 ex1p
// mpirun -np 4 ex1p --source_refinements 1 --dest_refinements 2
// mpirun -np 4 ex1p -s ../../data/inline-hex.mesh -d ../../data/inline-tet.mesh
//
// Description: This example code demonstrates the use of MFEM for transferring
// discrete fields from one conforming finite element mesh to another. The
// meshes can be of arbitrary shape and completely unrelated with
// each other. This feature can be used for implementing immersed
// domain methods for fluid-structure interaction or general
// multi-physics applications.
//
// This particular example is for parallel runtimes. Vector FE is
// an experimental feature in parallel. For non-conforming meshes
// please have a look at example "ex2p.cpp".
#include "example_utils.hpp"
#include "mfem.hpp"
#ifndef MFEM_USE_MOONOLITH
#error This example requires that MFEM is built with MFEM_USE_MOONOLITH=YES
#endif
using namespace mfem;
using namespace std;
void destination_transform(const Vector &x, Vector &x_new)
{
x_new = x;
// x_new *= 0.5;
}
int main(int argc, char *argv[])
{
MPI_Init(&argc, &argv);
int num_procs, rank;
MPI_Comm_size(MPI_COMM_WORLD, &num_procs);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
// Init transfer library context, with MPI handled outside the library
InitTransfer(argc, argv, MPI_COMM_WORLD);
const char *source_mesh_file = "../../data/inline-tri.mesh";
const char *destination_mesh_file = "../../data/inline-quad.mesh";
int src_n_refinements = 0;
int dest_n_refinements = 0;
int source_fe_order = 1;
int dest_fe_order = 1;
bool visualization = true;
bool use_vector_fe = false;
bool use_h1 = true;
bool use_vector_space = false;
bool verbose = false;
bool assemble_mass_and_coupling_together = true;
OptionsParser args(argc, argv);
args.AddOption(&source_mesh_file, "-s", "--source_mesh",
"Mesh file to use for src.");
args.AddOption(&destination_mesh_file, "-d", "--destination_mesh",
"Mesh file to use for dest.");
args.AddOption(&src_n_refinements, "-sr", "--source_refinements",
"Number of src refinements");
args.AddOption(&dest_n_refinements, "-dr", "--dest_refinements",
"Number of dest refinements");
args.AddOption(&visualization, "-vis", "--visualization", "-no-vis",
"--no-visualization",
"Enable or disable GLVis visualization.");
args.AddOption(&source_fe_order, "-so", "--source_fe_order",
"Order of the src finite elements");
args.AddOption(&dest_fe_order, "-do", "--dest_fe_order",
"Order of the dest finite elements");
args.AddOption(&verbose, "-verb", "--verbose", "--no-verb", "--no-verbose",
"Enable/Disable verbose output");
args.AddOption(&use_vector_fe, "-vfe", "--use_vector_fe", "-no-vfe",
"--no-vector_fe",
"Use RT|ND vector finite elements (Experimental)");
args.AddOption(&use_vector_space, "-vfs", "--use_vector_space", "-no-vfs",
"--no-vector_space",
"Use Lagrange vector finite elements (Experimental)");
args.AddOption(&use_h1, "-h1", "--use-h1", "-nh1", "--no-h1",
"Use H1 collection");
args.AddOption(&assemble_mass_and_coupling_together, "-act",
"--assemble_mass_and_coupling_together", "-no-act",
"--no-assemble_mass_and_coupling_together",
"Assemble mass and coupling operators together (better for "
"non-affine elements)");
args.Parse();
check_options(args);
if (use_vector_fe && use_vector_space)
{
mfem::err <<
"WARNING: use_vector_fe and use_vector_space options"
"are both true, ignoring use_vector_fe\n";
}
shared_ptr<Mesh> src_mesh, dest_mesh;
ifstream imesh;
imesh.open(destination_mesh_file);
if (imesh)
{
dest_mesh = make_shared<Mesh>(imesh, 1, 1);
imesh.close();
}
else
{
if (rank == 0)
mfem::err << "WARNING: Destination mesh file not found: "
<< destination_mesh_file << "\n"
<< "Using default 2D quad mesh.";
dest_mesh = make_shared<Mesh>(4, 4, Element::QUADRILATERAL);
}
const int dim = dest_mesh->Dimension();
dest_mesh->Transform(&destination_transform);
Vector box_min(dim), box_max(dim), range(dim);
dest_mesh->GetBoundingBox(box_min, box_max);
range = box_max;
range -= box_min;
imesh.open(source_mesh_file);
if (imesh)
{
src_mesh = make_shared<Mesh>(imesh, 1, 1);
imesh.close();
}
else
{
if (rank == 0)
mfem::err << "WARNING: Source mesh file not found: " << source_mesh_file
<< "\n"
<< "Using default box mesh.\n";
if (dim == 2)
{
src_mesh =
make_shared<Mesh>(4, 4, Element::TRIANGLE, 1, range[0], range[1]);
}
else if (dim == 3)
{
src_mesh = make_shared<Mesh>(4, 4, 4, Element::TETRAHEDRON, 1, range[0],
range[1], range[2]);
}
for (int i = 0; i < src_mesh->GetNV(); ++i)
{
double *v = src_mesh->GetVertex(i);
for (int d = 0; d < dim; ++d)
{
v[d] += box_min[d];
}
}
}
for (int i = 0; i < src_n_refinements; ++i)
{
src_mesh->UniformRefinement();
}
for (int i = 0; i < dest_n_refinements; ++i)
{
dest_mesh->UniformRefinement();
}
auto p_src_mesh = make_shared<ParMesh>(MPI_COMM_WORLD, *src_mesh);
auto p_dest_mesh = make_shared<ParMesh>(MPI_COMM_WORLD, *dest_mesh);
shared_ptr<FiniteElementCollection> src_fe_coll, dest_fe_coll;
if (use_vector_fe)
{
src_fe_coll =
make_shared<RT_FECollection>(source_fe_order, src_mesh->Dimension());
dest_fe_coll =
make_shared<RT_FECollection>(dest_fe_order, dest_mesh->Dimension());
}
else
{
if (use_h1)
{
src_fe_coll =
make_shared<H1_FECollection>(source_fe_order, src_mesh->Dimension());
dest_fe_coll =
make_shared<H1_FECollection>(dest_fe_order, dest_mesh->Dimension());
}
else
{
src_fe_coll =
make_shared<L2_FECollection>(source_fe_order, src_mesh->Dimension());
dest_fe_coll =
make_shared<L2_FECollection>(dest_fe_order, dest_mesh->Dimension());
}
}
auto src_fe = make_shared<ParFiniteElementSpace>(
p_src_mesh.get(), src_fe_coll.get(),
use_vector_space ? src_mesh->Dimension() : 1);
auto dest_fe = make_shared<ParFiniteElementSpace>(
p_dest_mesh.get(), dest_fe_coll.get(),
use_vector_space ? dest_mesh->Dimension() : 1);
ParGridFunction src_fun(src_fe.get());
// To be used with standard fe
FunctionCoefficient coeff(example_fun);
// To be used with vector fe
VectorFunctionCoefficient vector_coeff(dim, &vector_fun);
if (use_vector_fe || use_vector_space)
{
src_fun.ProjectCoefficient(vector_coeff);
src_fun.Update();
}
else
{
src_fun.ProjectCoefficient(coeff);
src_fun.Update();
}
ParGridFunction dest_fun(dest_fe.get());
dest_fun = 0.0;
dest_fun.Update();
ParMortarAssembler assembler(src_fe, dest_fe);
assembler.SetAssembleMassAndCouplingTogether(
assemble_mass_and_coupling_together);
assembler.SetVerbose(verbose);
if (use_vector_space)
{
assembler.AddMortarIntegrator(make_shared<LagrangeVectorL2MortarIntegrator>());
}
else if (use_vector_fe)
{
assembler.AddMortarIntegrator(make_shared<VectorL2MortarIntegrator>());
}
else
{
assembler.AddMortarIntegrator(make_shared<L2MortarIntegrator>());
}
if (assembler.Transfer(src_fun, dest_fun))
{
if (visualization)
{
double src_err = 0;
double dest_err = 0;
if (use_vector_fe)
{
src_err = src_fun.ComputeL2Error(vector_coeff);
dest_err = dest_fun.ComputeL2Error(vector_coeff);
}
else
{
src_err = src_fun.ComputeL2Error(coeff);
dest_err = dest_fun.ComputeL2Error(coeff);
}
if (rank == 0)
{
mfem::out << "l2 error: src: " << src_err << ", dest: " << dest_err
<< std::endl;
}
plot(*p_src_mesh, src_fun, "source", 0);
plot(*p_dest_mesh, dest_fun, "destination", 1);
}
}
else
{
mfem::out << "No intersection no transfer!" << std::endl;
}
// Finalize transfer library context
FinalizeTransfer();
return MPI_Finalize();
}