void
AStableDirk4::solve()
{
// Reset iteration counts
_n_nonlinear_iterations = 0;
_n_linear_iterations = 0;
if (_t_step == 1 && _safe_start)
{
_bootstrap_method->solve();
_n_nonlinear_iterations = _bootstrap_method->getNumNonlinearIterations();
_n_linear_iterations = _bootstrap_method->getNumLinearIterations();
}
else
{
// Time at end of step
Real time_old = _fe_problem.timeOld();
// A for-loop would increment _stage too far, so we use an extra
// loop counter. The method has three stages and an update stage,
// which we treat as just one more (special) stage in the implementation.
for (unsigned int current_stage = 1; current_stage < 5; ++current_stage)
{
// Set the current stage value
_stage = current_stage;
// This ensures that all the Output objects in the OutputWarehouse
// have had solveSetup() called, and sets the default solver
// parameters for PETSc.
_fe_problem.initPetscOutput();
if (current_stage < 4)
{
_console << "Stage " << _stage << "\n";
_fe_problem.time() = time_old + _c[_stage - 1] * _dt;
}
else
{
_console << "Update Stage.\n";
_fe_problem.time() = time_old + _dt;
}
// Do the solve
_fe_problem.getNonlinearSystemBase().system().solve();
// Update the iteration counts
_n_nonlinear_iterations += getNumNonlinearIterationsLastSolve();
_n_linear_iterations += getNumLinearIterationsLastSolve();
// Abort time step immediately on stage failure - see TimeIntegrator doc page
if (!_fe_problem.converged())
return;
}
}
}
void
ExplicitTVDRK2::solve()
{
Real time_new = _fe_problem.time();
Real time_old = _fe_problem.timeOld();
Real time_stage2 = time_old + _dt;
// Reset numbers of iterations
_n_nonlinear_iterations = 0;
_n_linear_iterations = 0;
// There is no work to do for the first stage (Y_1 = y_n). The
// first solve therefore happens in the second stage. Note that the
// non-time Kernels (which should be marked implicit=false) are
// evaluated at the old solution during this stage.
_fe_problem.initPetscOutput();
_console << "1st solve\n";
_stage = 2;
_fe_problem.timeOld() = time_old;
_fe_problem.time() = time_stage2;
_fe_problem.getNonlinearSystemBase().system().solve();
_n_nonlinear_iterations += getNumNonlinearIterationsLastSolve();
_n_linear_iterations += getNumLinearIterationsLastSolve();
// Advance solutions old->older, current->old. Also moves Material
// properties and other associated state forward in time.
_fe_problem.advanceState();
// The "update" stage (which we call stage 3) requires an additional
// solve with the mass matrix.
_fe_problem.initPetscOutput();
_console << "2nd solve\n";
_stage = 3;
_fe_problem.timeOld() = time_stage2;
_fe_problem.time() = time_new;
_fe_problem.getNonlinearSystemBase().system().solve();
_n_nonlinear_iterations += getNumNonlinearIterationsLastSolve();
_n_linear_iterations += getNumLinearIterationsLastSolve();
// Reset time at beginning of step to its original value
_fe_problem.timeOld() = time_old;
}