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Tempus
Version of the Day
Time Integration
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Partitioned Implicit-Explicit Runge-Kutta (IMEX-RK) time stepper. More...
#include <Tempus_StepperIMEX_RK_Partition_decl.hpp>
Public Member Functions | |
| StepperIMEX_RK_Partition (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, std::string stepperType="Partitioned IMEX RK SSP2") | |
| Constructor to use default Stepper parameters. More... | |
| StepperIMEX_RK_Partition (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, Teuchos::RCP< Teuchos::ParameterList > pList) | |
| Constructor to specialize Stepper parameters. More... | |
| StepperIMEX_RK_Partition (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &models, std::string stepperType, Teuchos::RCP< Teuchos::ParameterList > pList) | |
| Constructor for StepperFactory. More... | |
Basic stepper methods | |
| virtual void | setTableaus (Teuchos::RCP< Teuchos::ParameterList > pList, std::string stepperType="") |
| Set both the explicit and implicit tableau from ParameterList. More... | |
| virtual void | setExplicitTableau (std::string stepperType, Teuchos::RCP< Teuchos::ParameterList > pList) |
| Set the explicit tableau from ParameterList. More... | |
| virtual void | setExplicitTableau (Teuchos::RCP< const RKButcherTableau< Scalar > > explicitTableau) |
| Set the explicit tableau from tableau. More... | |
| virtual void | setImplicitTableau (std::string stepperType, Teuchos::RCP< Teuchos::ParameterList > pList) |
| Set the implicit tableau from ParameterList. More... | |
| virtual void | setImplicitTableau (Teuchos::RCP< const RKButcherTableau< Scalar > > implicitTableau) |
| Set the implicit tableau from tableau. More... | |
| virtual void | setModel (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel) |
| virtual Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > | getModel () |
| virtual void | setModelPair (const Teuchos::RCP< WrapperModelEvaluatorPairPartIMEX_Basic< Scalar > > &modelPair) |
| Create WrapperModelPairIMEX from user-supplied ModelEvaluator pair. More... | |
| virtual void | setModelPair (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &explicitModel, const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &implicitModel) |
| Create WrapperModelPairIMEX from explicit/implicit ModelEvaluators. More... | |
| virtual void | setObserver (Teuchos::RCP< StepperObserver< Scalar > > obs=Teuchos::null) |
| Set Observer. More... | |
| virtual void | initialize () |
| Initialize during construction and after changing input parameters. More... | |
| virtual void | takeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory) |
| Take the specified timestep, dt, and return true if successful. More... | |
| virtual Teuchos::RCP< Tempus::StepperState< Scalar > > | getDefaultStepperState () |
| Provide a StepperState to the SolutionState. This Stepper does not have any special state data, so just provide the base class StepperState with the Stepper description. This can be checked to ensure that the input StepperState can be used by this Stepper. More... | |
| virtual Scalar | getOrder () const |
| virtual Scalar | getOrderMin () const |
| virtual Scalar | getOrderMax () const |
| virtual bool | isExplicit () const |
| virtual bool | isImplicit () const |
| virtual bool | isExplicitImplicit () const |
| virtual bool | isOneStepMethod () const |
| virtual bool | isMultiStepMethod () const |
| virtual void | setInitialGuess (Teuchos::RCP< const Thyra::VectorBase< Scalar > > initial_guess) |
| Pass initial guess to Newton solver (only relevant for implicit solvers) More... | |
ParameterList methods | |
| void | setParameterList (const Teuchos::RCP< Teuchos::ParameterList > &pl) |
| Teuchos::RCP< Teuchos::ParameterList > | getNonconstParameterList () |
| Teuchos::RCP< Teuchos::ParameterList > | unsetParameterList () |
| Teuchos::RCP< const Teuchos::ParameterList > | getValidParameters () const |
| Teuchos::RCP< Teuchos::ParameterList > | getDefaultParameters () const |
Public Member Functions inherited from Tempus::StepperImplicit< Scalar > | |
| virtual void | setNonConstModel (const Teuchos::RCP< Thyra::ModelEvaluator< Scalar > > &appModel) |
| virtual void | setSolver (std::string solverName) |
| Set solver via ParameterList solver name. More... | |
| virtual void | setSolver (Teuchos::RCP< Teuchos::ParameterList > solverPL=Teuchos::null) |
| Set solver via solver ParameterList. More... | |
| virtual void | setSolver (Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > solver) |
| Set solver. More... | |
| virtual Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > | getSolver () const |
| Get solver. More... | |
| virtual std::string | getStepperType () const |
| const Thyra::SolveStatus< Scalar > | solveImplicitODE (const Teuchos::RCP< Thyra::VectorBase< Scalar > > &x) |
| Solve problem using x in-place. More... | |
| virtual void | setZeroInitialGuess (bool zIG) |
| Set parameter so that the initial guess is set to zero (=True) or use last timestep (=False). More... | |
| virtual bool | getZeroInitialGuess () const |
| virtual bool | getEmbedded () const |
| virtual Scalar | getInitTimeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory) const |
Public Member Functions inherited from Tempus::Stepper< Scalar > | |
| virtual void | createSubSteppers (std::vector< Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > > models) |
| void | validExplicitODE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const |
| Validate that the model supports explicit ODE evaluation, f(x,t) [=xdot]. More... | |
| void | validSecondOrderExplicitODE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const |
| Validate that the model supports explicit second order ODE evaluation, f(x,xdot,t) [=xdotdot]. More... | |
| void | validImplicitODE_DAE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const |
| Validate ME supports implicit ODE/DAE evaluation, f(xdot,x,t) [= 0]. More... | |
| void | validSecondOrderODE_DAE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const |
| Validate ME supports 2nd order implicit ODE/DAE evaluation, f(xdotdot,xdot,x,t) [= 0]. More... | |
| Teuchos::RCP< Teuchos::ParameterList > | defaultSolverParameters () const |
Overridden from Teuchos::Describable | |
| std::string | description_ |
| Teuchos::RCP< const RKButcherTableau< Scalar > > | explicitTableau_ |
| Teuchos::RCP< const RKButcherTableau< Scalar > > | implicitTableau_ |
| Scalar | order_ |
| Teuchos::RCP< Thyra::VectorBase< Scalar > > | stageZ_ |
| std::vector< Teuchos::RCP< Thyra::VectorBase< Scalar > > > | stageF_ |
| std::vector< Teuchos::RCP< Thyra::VectorBase< Scalar > > > | stageGx_ |
| Teuchos::RCP< Thyra::VectorBase< Scalar > > | xTilde_ |
| Teuchos::RCP< StepperObserver< Scalar > > | stepperObserver_ |
| Teuchos::RCP< StepperIMEX_RKPartObserver< Scalar > > | stepperIMEX_RKPartObserver_ |
| Teuchos::RCP< const Thyra::VectorBase< Scalar > > | initial_guess_ |
| virtual std::string | description () const |
| virtual void | describe (Teuchos::FancyOStream &out, const Teuchos::EVerbosityLevel verbLevel) const |
| void | evalImplicitModelExplicitly (const Teuchos::RCP< const Thyra::VectorBase< Scalar > > &X, const Teuchos::RCP< const Thyra::VectorBase< Scalar > > &Y, Scalar time, Scalar stepSize, Scalar stageNumber, const Teuchos::RCP< Thyra::VectorBase< Scalar > > &G) const |
| void | evalExplicitModel (const Teuchos::RCP< const Thyra::VectorBase< Scalar > > &X, Scalar time, Scalar stepSize, Scalar stageNumber, const Teuchos::RCP< Thyra::VectorBase< Scalar > > &F) const |
| StepperIMEX_RK_Partition () | |
| Default Constructor – not allowed. More... | |
Additional Inherited Members | |
Protected Attributes inherited from Tempus::StepperImplicit< Scalar > | |
| Teuchos::RCP< Teuchos::ParameterList > | stepperPL_ |
| Teuchos::RCP< WrapperModelEvaluator< Scalar > > | wrapperModel_ |
| Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > | solver_ |
| Teuchos::RCP< const Thyra::VectorBase< Scalar > > | initial_guess_ |
Partitioned Implicit-Explicit Runge-Kutta (IMEX-RK) time stepper.
Partitioned IMEX-RK is similar to the IMEX-RK (StepperIMEX_RK), except a portion of the solution only requires explicit integration, and should not be part of the implicit solution to reduce computational costs. Again our ODE can be written as
but now
where
is the product vector of
and
,
is still the "slow" physics (and evolved explicitly), and
is still the "fast" physics (and evolved implicitly), but a portion of the solution vector,
, is "explicit-only" and is only evolved by
, while
is the Implicit/Explicit (IMEX) solution vector, and is evolved explicitly by
evolved implicitly by
. Note we can expand this to explicitly show all the terms as
or
where
,
, and
, or
where
, and
. Using Butcher tableaus for the explicit terms
the basic scheme for this partitioned,
-stage, IMEX-RK is
or expanded
where
and
.
For iterative solvers, it is useful to write the stage solutions as
or expanded as
where
and note that
. Rearranging to solve for the implicit term
We additionally need the time derivative at each stage for the implicit solve. Let us define the following time derivative for
portion of the solution
where we split
arguments into
and
to emphasize that
is the solution for the implicit solve and
are parameters in this set of equations. The above time derivative,
, is NOT likely the same as the real time derivative,
, unless
(Reasoning:
and
unless
). Also note that the explicit term,
, is evaluated at the implicit stage time,
.
We can form the time derivative
Returning to the governing equation for the IMEX solution vector,
Recall
and if we define a pseudo time derivative, which is equivalent to the time derivative for the implicit solve,
we can write
For general DIRK methods, we need to also handle the case when
. The IMEX stage values can be simply evaluated similiar to the "explicit-only" stage values, e.g.,
and then we can simply evaluate
We can then form the time derivative as
but again note that the explicit term,
, is evaluated at the implicit stage time,
.
Partitioned IMEX-RK Algorithm The single-timestep algorithm for the partitioned IMEX-RK is
(Recall
)
do
![$\tilde{X} \leftarrow x_{n-1} - \Delta t\,\sum_{j=1}^{i-1} \left[ \hat{a}_{ij}\, f^x_j + a_{ij}\, g^x_j \right] $](form_186.png)




for
where
are known parameters

[Optional]
[Optional]

for
[Optional]Definition at line 228 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
| Tempus::StepperIMEX_RK_Partition< Scalar >::StepperIMEX_RK_Partition | ( | const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > & | appModel, |
| std::string | stepperType = "Partitioned IMEX RK SSP2" |
||
| ) |
Constructor to use default Stepper parameters.
Definition at line 28 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
| Tempus::StepperIMEX_RK_Partition< Scalar >::StepperIMEX_RK_Partition | ( | const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > & | appModel, |
| Teuchos::RCP< Teuchos::ParameterList > | pList | ||
| ) |
Constructor to specialize Stepper parameters.
Definition at line 39 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
| Tempus::StepperIMEX_RK_Partition< Scalar >::StepperIMEX_RK_Partition | ( | const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > & | models, |
| std::string | stepperType, | ||
| Teuchos::RCP< Teuchos::ParameterList > | pList | ||
| ) |
Constructor for StepperFactory.
Definition at line 51 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Default Constructor – not allowed.
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Definition at line 646 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Definition at line 639 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
| void Tempus::StepperIMEX_RK_Partition< Scalar >::evalExplicitModel | ( | const Teuchos::RCP< const Thyra::VectorBase< Scalar > > & | X, |
| Scalar | time, | ||
| Scalar | stepSize, | ||
| Scalar | stageNumber, | ||
| const Teuchos::RCP< Thyra::VectorBase< Scalar > > & | F | ||
| ) | const |
Definition at line 429 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
| void Tempus::StepperIMEX_RK_Partition< Scalar >::evalImplicitModelExplicitly | ( | const Teuchos::RCP< const Thyra::VectorBase< Scalar > > & | X, |
| const Teuchos::RCP< const Thyra::VectorBase< Scalar > > & | Y, | ||
| Scalar | time, | ||
| Scalar | stepSize, | ||
| Scalar | stageNumber, | ||
| const Teuchos::RCP< Thyra::VectorBase< Scalar > > & | G | ||
| ) | const |
Definition at line 394 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 687 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Provide a StepperState to the SolutionState. This Stepper does not have any special state data, so just provide the base class StepperState with the Stepper description. This can be checked to ensure that the input StepperState can be used by this Stepper.
Implements Tempus::Stepper< Scalar >.
Definition at line 630 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Reimplemented from Tempus::StepperImplicit< Scalar >.
Definition at line 272 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
| Teuchos::RCP< Teuchos::ParameterList > Tempus::StepperIMEX_RK_Partition< Scalar >::getNonconstParameterList | ( | ) |
Definition at line 702 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 294 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 296 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 295 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
| Teuchos::RCP< const Teuchos::ParameterList > Tempus::StepperIMEX_RK_Partition< Scalar >::getValidParameters | ( | ) | const |
Definition at line 673 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Initialize during construction and after changing input parameters.
Implements Tempus::Stepper< Scalar >.
Definition at line 352 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 298 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 300 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 299 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 303 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Implements Tempus::Stepper< Scalar >.
Definition at line 302 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Set the explicit tableau from ParameterList.
Definition at line 217 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Set the explicit tableau from tableau.
Definition at line 230 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Set the implicit tableau from ParameterList.
Definition at line 242 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Set the implicit tableau from tableau.
Definition at line 258 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Pass initial guess to Newton solver (only relevant for implicit solvers)
Reimplemented from Tempus::StepperImplicit< Scalar >.
Definition at line 308 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Reimplemented from Tempus::StepperImplicit< Scalar >.
Definition at line 269 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Create WrapperModelPairIMEX from explicit/implicit ModelEvaluators.
Use the supplied explicit/implicit MEs to create a WrapperModelPairIMEX with basic IMEX interactions between explicit and implicit MEs.
Definition at line 317 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Create WrapperModelPairIMEX from user-supplied ModelEvaluator pair.
The user-supplied ME pair can contain any user-specific IMEX interactions between explicit and implicit MEs.
Definition at line 295 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Set Observer.
Implements Tempus::Stepper< Scalar >.
Definition at line 330 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
| void Tempus::StepperIMEX_RK_Partition< Scalar >::setParameterList | ( | const Teuchos::RCP< Teuchos::ParameterList > & | pl | ) |
Definition at line 657 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Set both the explicit and implicit tableau from ParameterList.
Definition at line 64 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Take the specified timestep, dt, and return true if successful.
Implements Tempus::Stepper< Scalar >.
Definition at line 465 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
| Teuchos::RCP< Teuchos::ParameterList > Tempus::StepperIMEX_RK_Partition< Scalar >::unsetParameterList | ( | ) |
Definition at line 710 of file Tempus_StepperIMEX_RK_Partition_impl.hpp.
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Definition at line 345 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 346 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 347 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 360 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 349 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 352 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 353 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 351 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 358 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 357 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.
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Definition at line 355 of file Tempus_StepperIMEX_RK_Partition_decl.hpp.