SimulatorReport
NonlinearSolver<PhysicalModel>::
step(const SimulatorTimerInterface& timer,
const ReservoirState& initial_reservoir_state,
const WellState& initial_well_state,
ReservoirState& reservoir_state,
WellState& well_state)
{
SimulatorReport iterReport;
SimulatorReport report;
failureReport_ = SimulatorReport();
// Do model-specific once-per-step calculations.
model_->prepareStep(timer, initial_reservoir_state, initial_well_state);
int iteration = 0;
// Let the model do one nonlinear iteration.
// Set up for main solver loop.
bool converged = false;
// ---------- Main nonlinear solver loop ----------
do {
try {
// Do the nonlinear step. If we are in a converged state, the
// model will usually do an early return without an expensive
// solve, unless the minIter() count has not been reached yet.
iterReport = model_->nonlinearIteration(iteration, timer, *this, reservoir_state, well_state);
report += iterReport;
report.converged = iterReport.converged;
converged = report.converged;
iteration += 1;
}
catch (...) {
// if an iteration fails during a time step, all previous iterations
// count as a failure as well
failureReport_ += report;
failureReport_ += model_->failureReport();
throw;
}
} while ( (!converged && (iteration <= maxIter())) || (iteration <= minIter()));
if (!converged) {
failureReport_ += report;
std::string msg = "Solver convergence failure - Failed to complete a time step within " + std::to_string(maxIter()) + " iterations.";
OPM_THROW_NOLOG(Opm::TooManyIterations, msg);
}
// Do model-specific post-step actions.
model_->afterStep(timer, reservoir_state, well_state);
report.converged = true;
return report;
}
SimulatorReport nonlinearIteration(const int iteration,
const SimulatorTimerInterface& timer,
NonlinearSolverType& nonlinear_solver)
{
SimulatorReport report;
failureReport_ = SimulatorReport();
Dune::Timer perfTimer;
perfTimer.start();
if (iteration == 0) {
// For each iteration we store in a vector the norms of the residual of
// the mass balance for each active phase, the well flux and the well equations.
residual_norms_history_.clear();
current_relaxation_ = 1.0;
dx_old_ = 0.0;
convergence_reports_.push_back({timer.reportStepNum(), timer.currentStepNum(), {}});
convergence_reports_.back().report.reserve(11);
}
report.total_linearizations = 1;
try {
report += assembleReservoir(timer, iteration);
report.assemble_time += perfTimer.stop();
}
catch (...) {
report.assemble_time += perfTimer.stop();
failureReport_ += report;
// todo (?): make the report an attribute of the class
throw; // continue throwing the stick
}
std::vector<double> residual_norms;
perfTimer.reset();
perfTimer.start();
// the step is not considered converged until at least minIter iterations is done
{
auto convrep = getConvergence(timer, iteration,residual_norms);
report.converged = convrep.converged() && iteration > nonlinear_solver.minIter();;
ConvergenceReport::Severity severity = convrep.severityOfWorstFailure();
convergence_reports_.back().report.push_back(std::move(convrep));
// Throw if any NaN or too large residual found.
if (severity == ConvergenceReport::Severity::NotANumber) {
OPM_THROW(Opm::NumericalIssue, "NaN residual found!");
} else if (severity == ConvergenceReport::Severity::TooLarge) {
OPM_THROW(Opm::NumericalIssue, "Too large residual found!");
}
}
// checking whether the group targets are converged
if (wellModel().wellCollection().groupControlActive()) {
report.converged = report.converged && wellModel().wellCollection().groupTargetConverged(wellModel().wellState().wellRates());
}
report.update_time += perfTimer.stop();
residual_norms_history_.push_back(residual_norms);
if (!report.converged) {
perfTimer.reset();
perfTimer.start();
report.total_newton_iterations = 1;
// enable single precision for solvers when dt is smaller then 20 days
//residual_.singlePrecision = (unit::convert::to(dt, unit::day) < 20.) ;
// Compute the nonlinear update.
const int nc = UgGridHelpers::numCells(grid_);
BVector x(nc);
// apply the Schur compliment of the well model to the reservoir linearized
// equations
wellModel().linearize(ebosSimulator().model().linearizer().jacobian(),
ebosSimulator().model().linearizer().residual());
// Solve the linear system.
linear_solve_setup_time_ = 0.0;
try {
solveJacobianSystem(x);
report.linear_solve_setup_time += linear_solve_setup_time_;
report.linear_solve_time += perfTimer.stop();
report.total_linear_iterations += linearIterationsLastSolve();
}
catch (...) {
report.linear_solve_setup_time += linear_solve_setup_time_;
report.linear_solve_time += perfTimer.stop();
report.total_linear_iterations += linearIterationsLastSolve();
failureReport_ += report;
throw; // re-throw up
}
perfTimer.reset();
perfTimer.start();
// handling well state update before oscillation treatment is a decision based
// on observation to avoid some big performance degeneration under some circumstances.
// there is no theorectical explanation which way is better for sure.
wellModel().postSolve(x);
if (param_.use_update_stabilization_) {
// Stabilize the nonlinear update.
bool isOscillate = false;
bool isStagnate = false;
nonlinear_solver.detectOscillations(residual_norms_history_, iteration, isOscillate, isStagnate);
if (isOscillate) {
current_relaxation_ -= nonlinear_solver.relaxIncrement();
current_relaxation_ = std::max(current_relaxation_, nonlinear_solver.relaxMax());
if (terminalOutputEnabled()) {
std::string msg = " Oscillating behavior detected: Relaxation set to "
+ std::to_string(current_relaxation_);
OpmLog::info(msg);
}
}
nonlinear_solver.stabilizeNonlinearUpdate(x, dx_old_, current_relaxation_);
}
// Apply the update, with considering model-dependent limitations and
// chopping of the update.
updateSolution(x);
report.update_time += perfTimer.stop();
}
return report;
}
