Dear experienced deal.II users and developers,
I want to solve a heat equation in the time domain with distributed memory
using MPI, but the results are incorrect. In order to do so, I reference
tutorial step-23 for time updating method and step-40 for implementing MPI.
May I ask whether my boundary condition is right or not? Should we do
compress() after apply_boundary_values()? Thanks in advance!
With best regards,
Mark
In PETsc or Trilinos, how could we set the boundary conditions and initial
conditions?
Since old_solution_T would be read in other places (not shown here), it is
initialized with ghost cells; while old_solutuon_T_cal is only used for
written, it does not have ghost cells. see code as following,
//
old_solution_T_cal.reinit (locally_owned_dofs,mpi_communicator);
old_solution_T.reinit
(locally_owned_dofs,locally_relevant_dofs,mpi_communicator);
//
..........
template <int dim>
void ThermalDiffusion<dim>::run ()
{
setup_system();
assemble_system();
VectorTools::project (dof_handler, constraints, QGauss<dim>(degree),
InitialValues_T<dim>(),
old_solution_T_cal);
old_solution_T = old_solution_T_cal;
LA::MPI::Vector tmp (locally_owned_dofs,mpi_communicator);
LA::MPI::Vector forcing_terms (locally_owned_dofs,mpi_communicator);
for (timestep_number=1, time=time_step;
time<= global_simulation_end_time;
time+=time_step, ++timestep_number)
{
pcout << "Time step " << timestep_number
<< " at t=" << time
<< std::endl;
//-----------------------------------
//run to solve T
//-----------------------------------
//
//time dependent
//assign right hand side
mass_matrix_T.vmult (system_rhs, old_solution_T_cal);
laplace_matrix_T.vmult (tmp, old_solution_T_cal);
system_rhs.add (-time_step * (1-theta), tmp);
assemble_rhs_T (time);
forcing_terms = dynamic_rhs_T;
forcing_terms *= time_step * theta;
assemble_rhs_T (time - time_step);
tmp = dynamic_rhs_T;
forcing_terms.add (time_step*(1-theta),tmp);
system_rhs.add (1,forcing_terms);
//assign system matrix
system_matrix.copy_from (mass_matrix_T);
system_matrix.add (time_step * theta, laplace_matrix_T);
* { BoundaryValues_Temperature<dim>
boundary_values_function_T; //boundary_values_function.set_time
(time); std::map<types::global_dof_index,double>
boundary_values_T; VectorTools::interpolate_boundary_values
(dof_handler,
BOUNDARY_NUM,
boundary_values_function_T,
boundary_values_T); MatrixTools::apply_boundary_values
(boundary_values_T,
system_matrix,
solution_T,
system_rhs, false); }*
solve_T ();
if (Utilities::MPI::n_mpi_processes(mpi_communicator) <= 32)
{
TimerOutput::Scope t(computing_timer,"output");
output_results ();
}
computing_timer.print_summary ();
computing_timer.reset();
pcout << std::endl;
old_solution_T = solution_T;
}
}
}
//definition of solve_T()
template <int dim>
void ThermalDiffusion<dim>::solve_T ()
{
TimerOutput::Scope t(computing_timer,"solve_T");
LA::MPI::Vector completely_distributed_solution
(locally_owned_dofs,mpi_communicator);
SolverControl solver_control (dof_handler.n_dofs(),1e-12);
#ifdef USE_PETSC_LA
LA::SolverCG solver(solver_control,mpi_communicator);
#else
LA::SolverCG solver(solver_control);
#endif
LA::MPI::PreconditionAMG preconditioner;
LA::MPI::PreconditionAMG::AdditionalData data;
#ifdef USE_PETSC_LA
data.symmetric_operator = true;
#else
/* Trilinos defaults are good */
#endif
preconditioner.initialize(system_matrix,data);
solver.solve
(system_matrix,completely_distributed_solution,system_rhs,preconditioner);
pcout << " Solved in " << solver_control.last_step()
<< " iterations."<< std::endl;
constraints.distribute (solution_T);
solution_T = completely_distributed_solution;
pcout << "success...solve_T()..." <<std::endl;
}
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