systems_of_equations_ex9.C File Reference

Go to the source code of this file.

Classes
class	AzimuthalPeriodicBoundary
class	LinearElasticity

Functions
int	main (int argc, char **argv)

Function Documentation

main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 335 of file systems_of_equations_ex9.C.

References libMesh::DofMap::add_dirichlet_boundary(), libMesh::DofMap::add_periodic_boundary(), libMesh::System::add_variable(), libMesh::System::attach_assemble_object(), libMesh::default_solver_package(), dim, libMesh::FIRST, libMesh::System::get_dof_map(), libMesh::TriangleWrapper::init(), libMesh::INVALID_SOLVER_PACKAGE, libMesh::LAGRANGE, mesh, libMesh::PeriodicBoundaryBase::myboundary, libMesh::PeriodicBoundaryBase::pairedboundary, libMesh::pi, libMesh::MeshBase::print_info(), libMesh::MeshBase::read(), libMesh::Real, libMesh::LinearImplicitSystem::solve(), libMesh::MeshRefinement::uniformly_refine(), and libMesh::ExodusII_IO::write_equation_systems().

{
  // Initialize libMesh and any dependent libraries
  LibMeshInit init (argc, argv);

  // This example requires a linear solver package.
  libmesh_example_requires(libMesh::default_solver_package() != INVALID_SOLVER_PACKAGE,
                           "--enable-petsc, --enable-trilinos, or --enable-eigen");

#ifndef LIBMESH_HAVE_EXODUS_API
  // example requires ExodusII to load the mesh
  libmesh_example_requires(false, "--enable-exodus");
#endif

  // We use Dirichlet and Periodic boundary conditions here
#ifndef LIBMESH_ENABLE_DIRICHLET
  libmesh_example_requires(false, "--enable-dirichlet");
#endif
#ifndef LIBMESH_ENABLE_PERIODIC
  libmesh_example_requires(false, "--enable-periodic");
#endif

  // Initialize the cantilever mesh
  const unsigned int dim = 3;

  // Make sure libMesh was compiled for 3D
  libmesh_example_requires(dim == LIBMESH_DIM, "3D support");

  // Make sure libMesh has normal boundary id sizes
  libmesh_example_requires(sizeof(boundary_id_type) > 1, "boundary_id_size > 1");

#if LIBMESH_BOUNDARY_ID_BYTES > 1
  // Create a 3D mesh distributed across the default MPI communicator.
  Mesh mesh(init.comm());

  // Create an equation systems object.
  EquationSystems equation_systems (mesh);

  // Declare the system and its variables.
  // Create a system named "Elasticity"
  LinearImplicitSystem & system =
    equation_systems.add_system<LinearImplicitSystem> ("Elasticity");

#ifdef LIBMESH_ENABLE_PERIODIC
  // Add two azimuthal periodic boundaries on two adjacent domains.
  // We do this to show that the periodic boundary condition that
  // we impose leads to a continuous solution across adjacent domains.
  //
  // We add the periodic boundaries *before* reading the Mesh, so
  // that periodic neighbors will be retained when a DistributedMesh
  // is distributed.
  //
  // The angle specified below defines the mapping
  // from "pairedboundary" to "myboundary".
  {
    Point center(0., 0., 0.);
    Point axis(0., 0., 1.);
    Real angle = 2*libMesh::pi/12.0;
    AzimuthalPeriodicBoundary periodic_bc(center, axis, angle);
    periodic_bc.myboundary = 301;
    periodic_bc.pairedboundary = 302;
    system.get_dof_map().add_periodic_boundary(periodic_bc);
  }
  {
    Point center(0., 0., 0.);
    Point axis(0., 0., 1.);
    Real angle = 2*libMesh::pi/12.0;
    AzimuthalPeriodicBoundary periodic_bc(center, axis, angle);
    periodic_bc.myboundary = 401;
    periodic_bc.pairedboundary = 402;
    system.get_dof_map().add_periodic_boundary(periodic_bc);
  }
#endif // LIBMESH_ENABLE_PERIODIC

  mesh.read("systems_of_equations_ex9.exo");

  GetPot input(argc, argv);
  const unsigned int n_refinements = input("n_refinements", 0);
  // Skip adaptive runs on a non-adaptive libMesh build
#ifndef LIBMESH_ENABLE_AMR
  libmesh_example_requires(n_refinements==0, "--enable-amr");
#else
  MeshRefinement mesh_refinement(mesh);
  mesh_refinement.uniformly_refine(n_refinements);
#endif

  // Print information about the mesh to the screen.
  mesh.print_info();

  // Add three displacement variables, u and v, to the system
  unsigned int u_var = system.add_variable("u", FIRST, LAGRANGE);
  unsigned int v_var = system.add_variable("v", FIRST, LAGRANGE);
  unsigned int w_var = system.add_variable("w", FIRST, LAGRANGE);

  LinearElasticity le(equation_systems);
  system.attach_assemble_object(le);

  ZeroFunction<> zf;

#ifdef LIBMESH_ENABLE_DIRICHLET
  DirichletBoundary clamped_bc({300,400}, {u_var,v_var,w_var}, zf);
  system.get_dof_map().add_dirichlet_boundary(clamped_bc);
#endif

  // Initialize the data structures for the equation system.
  equation_systems.init();

  // Print information about the system to the screen.
  equation_systems.print_info();

  // Solve the system
  system.solve();

  // Plot the solution
#ifdef LIBMESH_HAVE_EXODUS_API

  ExodusII_IO (mesh).write_equation_systems("solution.exo",
                                            equation_systems);

#endif // #ifdef LIBMESH_HAVE_EXODUS_API
#endif // #if LIBMESH_BOUNDARY_ID_BYTES > 1

  // All done.
  return 0;
}