From 3dbe82b4e7558880ef144d874b6da30585fff1b9 Mon Sep 17 00:00:00 2001
From: Wenqing Wang <wenqing.wang@ufz.de>
Date: Thu, 20 Apr 2017 18:10:15 +0200
Subject: [PATCH] [dt] Added computeTimeStepping
---
ProcessLib/UncoupledProcessesTimeLoop.cpp | 152 ++++++++++++++++------
ProcessLib/UncoupledProcessesTimeLoop.h | 10 ++
2 files changed, 123 insertions(+), 39 deletions(-)
diff --git a/ProcessLib/UncoupledProcessesTimeLoop.cpp b/ProcessLib/UncoupledProcessesTimeLoop.cpp
index 78885d772d3..664ddf926ac 100644
--- a/ProcessLib/UncoupledProcessesTimeLoop.cpp
+++ b/ProcessLib/UncoupledProcessesTimeLoop.cpp
@@ -8,6 +8,7 @@
*/
#include "UncoupledProcessesTimeLoop.h"
+
#include "BaseLib/uniqueInsert.h"
#include "BaseLib/RunTime.h"
#include "NumLib/ODESolver/TimeDiscretizationBuilder.h"
@@ -493,9 +494,6 @@ bool solveOneTimeStepOneProcess(GlobalVector& x, std::size_t const timestep,
bool nonlinear_solver_succeeded =
nonlinear_solver.solve(x, coupling_term, post_iteration_callback);
- auto& mat_strg = *process_data.mat_strg;
- time_disc.pushState(t, x, mat_strg);
-
return nonlinear_solver_succeeded;
}
@@ -568,6 +566,89 @@ bool UncoupledProcessesTimeLoop::setCoupledSolutions()
return true;
}
+double UncoupledProcessesTimeLoop::computeTimeSteppping(
+ const double t, const std::size_t timesteps, std::size_t& accepted_steps,
+ std::size_t& rejected_steps)
+{
+ bool all_process_steps_accepted = true;
+ // Get minimum time step size among step sizes of all processes.
+ double dt = std::numeric_limits<double>::max();
+ for (std::size_t i = 0; i < _per_process_data.size(); i++)
+ {
+ const auto& ppd = *_per_process_data[i];
+ const auto& timestepper = ppd.timestepper;
+ if (t > timestepper->end())
+ // skip the process that already reaches the ending time.
+ continue;
+
+ auto& time_disc = ppd.time_disc;
+ auto const& x = *_process_solutions[i];
+
+ const double solution_error =
+ (t == timestepper->begin())
+ ? 0.
+ : time_disc->getRelativeError(
+ x, timestepper->getSolutionNormType());
+ if (!timestepper->next(solution_error))
+ {
+ // Not all processes have accepted steps.
+ all_process_steps_accepted = false;
+ }
+
+ if (timestepper->getTimeStep().dt() < dt)
+ {
+ dt = timestepper->getTimeStep().dt();
+ }
+ }
+
+ bool is_initial_step = false;
+ // Reset the time step with the minimum step size, dt
+ // Update the solution of the previous time step in time_disc.
+ for (std::size_t i = 0; i < _per_process_data.size(); i++)
+ {
+ const auto& ppd = *_per_process_data[i];
+ auto& timestepper = ppd.timestepper;
+ timestepper->resetCurrentTimeStep(dt);
+
+ if (t == timestepper->begin())
+ {
+ is_initial_step = true;
+ continue;
+ }
+
+ if (all_process_steps_accepted)
+ {
+ auto& time_disc = ppd.time_disc;
+ auto& mat_strg = *ppd.mat_strg;
+ auto const& x = *_process_solutions[i];
+ time_disc->pushState(t, x, mat_strg);
+ }
+ else
+ {
+ WARN(
+ "Time step %d is rejected. "
+ "The computation is back to the previous time.",
+ timesteps)
+ }
+ }
+
+ if (!is_initial_step)
+ {
+ if (all_process_steps_accepted)
+ accepted_steps++;
+ else
+ rejected_steps++;
+ }
+
+ // Adjust step size if t < _end_time, while t+dt exceeds the end time
+ if (t < _end_time && t + dt > _end_time)
+ {
+ dt = _end_time - t;
+ }
+
+ return dt;
+}
+
/*
* TODO:
* Now we have a structure inside the time loop which is very similar to the
@@ -621,63 +702,56 @@ bool UncoupledProcessesTimeLoop::loop()
const bool is_staggered_coupling = setCoupledSolutions();
double t = _start_time;
- std::size_t timestep = 1; // the first timestep really is number one
+ std::size_t timesteps = 1; // the first timestep really is number one
+ std::size_t accepted_steps = 0;
+ std::size_t rejected_steps = 0;
bool nonlinear_solver_succeeded = true;
+ double dt =
+ computeTimeSteppping(t, timesteps, accepted_steps, rejected_steps);
+
while (t < _end_time)
{
BaseLib::RunTime time_timestep;
time_timestep.start();
- // Find the minimum time step size among the predicted step sizes of
- // processes and step it as common time step size.
- double dt = std::numeric_limits<double>::max();
- for (std::size_t i = 0; i < _per_process_data.size(); i++)
- {
- const auto& timestepper = _per_process_data[i]->timestepper;
- if (t > timestepper->end()) // skip the process that already stops
- continue;
-
- // TODO SOON timestepper->next();
- if (timestepper->getTimeStep().dt() < dt)
- {
- dt = timestepper->getTimeStep().dt();
- }
- }
- // Adjust step size if t < _end_time, while t+dt exceeds the end time
- if (t < _end_time && t + dt > _end_time)
- {
- dt = _end_time - t;
- if (dt < std::numeric_limits<double>::epsilon())
- break; // break the time stepping loop
- }
-
t += dt;
- for (auto& spd : _per_process_data)
- {
- spd->timestepper->resetCurrentTimeStep(dt);
- }
-
INFO("=== timestep #%u (t=%gs, dt=%gs) ==============================",
- timestep, t, dt);
+ timesteps, t, dt);
if (is_staggered_coupling)
nonlinear_solver_succeeded =
- solveCoupledEquationSystemsByStaggeredScheme(t, dt, timestep);
+ solveCoupledEquationSystemsByStaggeredScheme(t, dt, timesteps);
else
nonlinear_solver_succeeded =
- solveUncoupledEquationSystems(t, dt, timestep);
+ solveUncoupledEquationSystems(t, dt, timesteps);
- INFO("[time] Time step #%u took %g s.", timestep,
+ INFO("[time] Time step #%u took %g s.", timesteps,
time_timestep.elapsed());
- timestep++;
+ dt = computeTimeSteppping(t, timesteps, accepted_steps, rejected_steps);
+
+ if (dt < std::numeric_limits<double>::epsilon())
+ {
+ WARN(
+ "Time step size of %g is too small.\n"
+ "Time stepping stops at step %u and at time of %g.",
+ dt, timesteps, t);
+ break;
+ }
+
+ timesteps++;
if (!nonlinear_solver_succeeded)
break;
}
+ INFO(
+ "The whole computation took %u steps, in which\n"
+ "\t accepted steps are %u, rejected steps are %u.\n",
+ timesteps, accepted_steps, rejected_steps)
+
// output last time step
if (nonlinear_solver_succeeded)
{
@@ -686,8 +760,8 @@ bool UncoupledProcessesTimeLoop::loop()
{
auto& pcs = spd->process;
auto const& x = *_process_solutions[pcs_idx];
- _output->doOutputLastTimestep(pcs, spd->process_output, timestep, t,
- x);
+ _output->doOutputLastTimestep(pcs, spd->process_output, timesteps,
+ t, x);
++pcs_idx;
}
diff --git a/ProcessLib/UncoupledProcessesTimeLoop.h b/ProcessLib/UncoupledProcessesTimeLoop.h
index f0c0e9fe00c..214fcbea461 100644
--- a/ProcessLib/UncoupledProcessesTimeLoop.h
+++ b/ProcessLib/UncoupledProcessesTimeLoop.h
@@ -112,6 +112,16 @@ private:
*/
bool solveCoupledEquationSystemsByStaggeredScheme(
const double t, const double dt, const std::size_t timestep_id);
+
+ /**
+ * Find the minimum time step size among the predicted step sizes of
+ * processes and step it as common time step size.
+ *
+ * @param t Current time
+ */
+ double computeTimeSteppping(const double t, const std::size_t timesteps,
+ std::size_t& accepted_steps,
+ std::size_t& rejected_steps);
};
//! Builds an UncoupledProcessesTimeLoop from the given configuration.
--
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