transient_ex3.C File Reference

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Functions
void	set_initial_condition (EquationSystems &es, const std::string &system_name)
Number	initial_condition (const Point &p, const Parameters &parameters, const std::string &, const std::string &)
int	main (int argc, char **argv)

Function Documentation

initial_condition()

Number initial_condition	(	const Point &	p,
		const Parameters &	parameters,
		const std::string &	,
		const std::string &
	)

Definition at line 138 of file transient_ex3.C.

References libMesh::Utility::pow(), and libMesh::Real.

Referenced by set_initial_condition().

{
  Real x = p(0);
  Real y = p(1);

  return std::exp( -100.*(std::pow(x-0.5,2.) + std::pow(y-0.5,2.)) );
}

main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 66 of file transient_ex3.C.

References libMesh::EquationSystems::add_system(), libMesh::ClawSystem::assemble_all_matrices(), libMesh::System::attach_init_function(), libMesh::MeshTools::Generation::build_square(), libMesh::default_solver_package(), libMesh::TriangleWrapper::init(), libMesh::EquationSystems::init(), libMesh::INVALID_SOLVER_PACKAGE, mesh, libMesh::MeshTools::n_elem(), libMesh::AdvectionSystem::print_info(), libMesh::EquationSystems::print_info(), libMesh::MeshBase::print_info(), libMesh::AdvectionSystem::process_parameters_file(), libMesh::QUAD9, set_initial_condition(), libMesh::ClawSystem::solve_conservation_law(), and libMesh::ExodusII_IO::write_equation_systems().

{
  // Initialize libMesh.
  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");

  // Create GetPot object to parse the command line
  GetPot command_line (argc, argv);

  // Allow the user specify a custom input file on the command line
  // using the "-i" flag, and provide a sensible default value in case
  // they don't.
  std::string parameters_filename = "advection_2D.in";
  if ( command_line.search(2, "-i", "--input_file") )
    parameters_filename = command_line.next(parameters_filename);

  // Read mesh options from the input file
  GetPot infile(parameters_filename);
  unsigned int n_elem = infile("n_elem", 1);       // Determines the number of elements in the "truth" mesh

  // Build a mesh
  Mesh mesh (init.comm());
  MeshTools::Generation::build_square (mesh,
                                       n_elem, n_elem,
                                       0., 1.,
                                       0., 1.,
                                       QUAD9);

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

  // Create an AdvectionSystem within the EquationSystems
  AdvectionSystem & advection_system =
    equation_systems.add_system<AdvectionSystem> ("Advection2D");

  // Process the input file values
  advection_system.process_parameters_file(parameters_filename);

  // Set the initial condition function
  advection_system.attach_init_function (set_initial_condition);

  equation_systems.init ();

  equation_systems.print_info();
  mesh.print_info();

  advection_system.print_info();

  advection_system.assemble_all_matrices();
  // advection_system.write_out_discretization_matrices();

#ifdef LIBMESH_HAVE_EXODUS_API
  ExodusII_IO(mesh).write_equation_systems ("claw_solution.0000.e", equation_systems);
#endif

  advection_system.solve_conservation_law();

  return 0;
}

set_initial_condition()

void set_initial_condition	(	EquationSystems &	es,
		const std::string &	system_name
	)

Definition at line 129 of file transient_ex3.C.

References libMesh::EquationSystems::get_system(), initial_condition(), libMesh::EquationSystems::parameters, and libMesh::System::project_solution().

Referenced by main().

{
  LinearImplicitSystem & system =
    es.get_system<LinearImplicitSystem>("Advection2D");

  system.project_solution(initial_condition, /*gradient=*/nullptr, es.parameters);
}