Hi, all.
I wonder if it is possible to pass solution vector to refined-meshed....
I am solving non-linear problem with iterative method.
I'd like to use coarse mesh solution as a initial solution to find accurate
solution fast.
However, my present code sets up system again on every refinement cycle.
So, I lose all solution that I had in coarse mesh.
I think it is really helpful for me if I knew a way to pass the previous
solution to as a initial solution for next iterative method.
I think it might be complicated... first vector size of solution might
different when mesh is refined....
is there anyone who has idea on this ?
Thanks,
Jaekwang Kim
template <int dim>
void nonlinear<dim>::run ()
{
unsigned int cycle_control=4;
for (unsigned int cycle=0; cycle<cycle_control; ++cycle)
{
std::cout << "Cycle " << cycle << ':' << std::endl;
if (cycle == 0)
{
GridGenerator::hyper_cube (triangulation, 0.0, 1.0);
triangulation.refine_global (1);
for (typename Triangulation<dim>::active_cell_iterator
cell=triangulation.begin_active();
cell!=triangulation.end(); ++cell)
{
for (unsigned int f=0; f<GeometryInfo<dim>::faces_per_cell;
++f)
{
if (cell->face(f)->at_boundary() == true)
{
if ( std::abs(cell->face(f)->center()[0]-0.5)< 1e-12
)
{
cell->face(f)->set_boundary_id(10);
}
// Boundary faces
static const double tol = 1e-12;
if ( std::abs(cell->face(f)->center()[0]-0.0)< tol )
{
cell->face(f)->set_boundary_id(1);
}
if ( std::abs(cell->face(f)->center()[0]-1.0)< tol )
{
cell->face(f)->set_boundary_id(1);
}
if ( std::abs(cell->face(f)->center()[1]-0.0)< tol )
{
cell->face(f)->set_boundary_id(1);
}
if ( std::abs(cell->face(f)->center()[1]-1.0)< tol )
{
cell->face(f)->set_boundary_id(1);
}
}
}
}
std::ofstream out ("grid-1.ucd");
GridOut grid_out;
grid_out.write_ucd (triangulation, out);
}
else
refine_grid ();
std::cout << " Number of active cells: "<<
triangulation.n_active_cells() << std::endl;
setup_system ();
int iteration=0;
assemble_system ();
solve ();
Vector<double> difference(dof_handler.n_dofs());
Vector<double> temp_vector(dof_handler.n_dofs());
Vector<double> temp_difference(dof_handler.n_dofs());
difference=solution; // std::cout << " ||u_k-u_{k-1}||" <<
difference.l2_norm() << std::endl;
previous_solution = solution ;
double omega = 0.5; //relxation control number
int success_step=0 ;
do{
assemble_system();
solve();
difference = solution;
difference -= previous_solution; //This is temporary step
temp_vector=solution;
temp_vector.add(omega,difference);
temp_difference = temp_vector;
temp_difference -= solution; //Calculate different again
if (temp_difference.l2_norm()< difference.l2_norm())
//temp_difference
= temp_vector - solution , difference=solution-previous_solution
{
success_step+=1;
difference=temp_vector;
difference-=solution ;
solution=temp_vector;
}
previous_solution=solution ;
iteration+=1;
std::ofstream outerror2("iter_error.dat",std::ios::app);
outerror2 << degree << " " << triangulation.n_active_cells() << "
" << iteration << " " << difference.l2_norm() << " " << error << std::endl;
}while (difference.l2_norm() > 0.00001);
std::cout << " ||u_k-u_{k-1}|| = " << difference.l2_norm() << "
Iteration Number: " << iteration << std::endl;
error_evaluation();
std::ofstream outerror("error.dat",std::ios::app);
outerror << degree << " " << triangulation.n_active_cells() << " "
<< iteration << " " << error << std::endl;
output_results ();
}
}
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