systems_of_equations_ex9.C File Reference

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Classes
class	AzimuthalPeriodicBoundary
class	LinearElasticity

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

Function Documentation

main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 345 of file systems_of_equations_ex9.C.

{
  // 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");
 
  // 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);
 
  std::vector<unsigned int> variables;
  variables.push_back(u_var);
  variables.push_back(v_var);
  variables.push_back(w_var);
  ZeroFunction<> zf;
  std::set<boundary_id_type> clamped_boundary_ids;
  clamped_boundary_ids.insert(300);
  clamped_boundary_ids.insert(400);
 
#ifdef LIBMESH_ENABLE_DIRICHLET
  DirichletBoundary clamped_bc(clamped_boundary_ids, variables, 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;
}

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(), and libMesh::MeshOutput< MT >::write_equation_systems().