Tempus
Version of the Day
Time Integration
|
Implicit-Explicit Runge-Kutta (IMEX-RK) time stepper. More...
#include <Tempus_StepperIMEX_RK_decl.hpp>
Public Member Functions | |
StepperIMEX_RK () | |
Default constructor. More... | |
StepperIMEX_RK (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, const Teuchos::RCP< StepperObserver< Scalar > > &obs, const Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > &solver, bool useFSAL, std::string ICConsistency, bool ICConsistencyCheck, bool zeroInitialGuess, std::string stepperType, Teuchos::RCP< const RKButcherTableau< Scalar > > explicitTableau, Teuchos::RCP< const RKButcherTableau< Scalar > > implicitTableau, Scalar order) | |
Constructor to specialize Stepper parameters. More... | |
virtual Scalar | getAlpha (const Scalar dt) const |
Return alpha = d(xDot)/dx. More... | |
virtual Scalar | getBeta (const Scalar) const |
Return beta = d(x)/dx. More... | |
Teuchos::RCP< const Teuchos::ParameterList > | getValidParameters () const |
void | evalImplicitModelExplicitly (const Teuchos::RCP< const Thyra::VectorBase< Scalar > > &X, 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 |
virtual bool | getICConsistencyCheckDefault () const |
void | setOrder (Scalar order) |
Basic stepper methods | |
virtual void | setTableaus (std::string stepperType="", Teuchos::RCP< const RKButcherTableau< Scalar > > explicitTableau=Teuchos::null, Teuchos::RCP< const RKButcherTableau< Scalar > > implicitTableau=Teuchos::null) |
Set both the explicit and implicit tableau from ParameterList. More... | |
virtual void | setExplicitTableau (Teuchos::RCP< const RKButcherTableau< Scalar > > explicitTableau) |
Set the explicit tableau from tableau. 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< WrapperModelEvaluatorPairIMEX_Basic< Scalar > > &mePair) |
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 Teuchos::RCP < StepperObserver< Scalar > > | getObserver () const |
Get Observer. More... | |
virtual void | initialize () |
Initialize during construction and after changing input parameters. More... | |
virtual void | setInitialConditions (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory) |
Set the initial conditions and make them consistent. 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 OrderODE | getOrderODE () const |
Overridden from Teuchos::Describable | |
virtual void | describe (Teuchos::FancyOStream &out, const Teuchos::EVerbosityLevel verbLevel) const |
Public Member Functions inherited from Tempus::StepperImplicit< Scalar > | |
virtual void | setNonConstModel (const Teuchos::RCP< Thyra::ModelEvaluator< Scalar > > &appModel) |
virtual Teuchos::RCP< const WrapperModelEvaluator< Scalar > > | getWrapperModel () |
virtual void | setSolver (Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > solver=Teuchos::null) |
Set solver. More... | |
virtual Teuchos::RCP < Thyra::NonlinearSolverBase < Scalar > > | getSolver () const |
Get solver. More... | |
const Thyra::SolveStatus< Scalar > | solveImplicitODE (const Teuchos::RCP< Thyra::VectorBase< Scalar > > &x) |
Solve problem using x in-place. (Needs to be deprecated!) More... | |
const Thyra::SolveStatus< Scalar > | solveImplicitODE (const Teuchos::RCP< Thyra::VectorBase< Scalar > > &x, const Teuchos::RCP< Thyra::VectorBase< Scalar > > &xDot, const Scalar time, const Teuchos::RCP< ImplicitODEParameters< Scalar > > &p) |
Solve implicit ODE, f(x, xDot, t, p) = 0. More... | |
void | evaluateImplicitODE (Teuchos::RCP< Thyra::VectorBase< Scalar > > &f, const Teuchos::RCP< Thyra::VectorBase< Scalar > > &x, const Teuchos::RCP< Thyra::VectorBase< Scalar > > &xDot, const Scalar time, const Teuchos::RCP< ImplicitODEParameters< Scalar > > &p) |
Evaluate implicit ODE residual, f(x, xDot, t, p). More... | |
virtual void | setInitialGuess (Teuchos::RCP< const Thyra::VectorBase< Scalar > > initial_guess) |
Pass initial guess to Newton solver (only relevant for implicit solvers) 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 Scalar | getInitTimeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &) const |
virtual void | setStepperXDot (Teuchos::RCP< Thyra::VectorBase< Scalar > > xDot) |
Set xDot for Stepper storage. More... | |
virtual Teuchos::RCP < Thyra::VectorBase< Scalar > > | getStepperXDot (Teuchos::RCP< SolutionState< Scalar > > state) |
Get xDot from SolutionState or Stepper storage. More... | |
virtual Teuchos::RCP < Thyra::VectorBase< Scalar > > | getStepperXDotDot (Teuchos::RCP< SolutionState< Scalar > > state) |
Get xDotDot from SolutionState or Stepper storage. More... | |
Public Member Functions inherited from Tempus::Stepper< Scalar > | |
void | setStepperType (std::string s) |
std::string | getStepperType () const |
void | setUseFSAL (bool a) |
bool | getUseFSAL () const |
virtual bool | getUseFSALDefault () const |
void | setICConsistency (std::string s) |
std::string | getICConsistency () const |
virtual std::string | getICConsistencyDefault () const |
void | setICConsistencyCheck (bool c) |
bool | getICConsistencyCheck () const |
virtual std::string | description () const |
virtual void | createSubSteppers (std::vector< Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > >) |
Protected Attributes | |
Teuchos::RCP< const RKButcherTableau< Scalar > > | explicitTableau_ |
Teuchos::RCP< const RKButcherTableau< Scalar > > | implicitTableau_ |
Scalar | order_ |
Teuchos::RCP < Thyra::VectorBase< Scalar > > | stageX_ |
std::vector< Teuchos::RCP < Thyra::VectorBase< Scalar > > > | stageF_ |
std::vector< Teuchos::RCP < Thyra::VectorBase< Scalar > > > | stageG_ |
Teuchos::RCP < Thyra::VectorBase< Scalar > > | xTilde_ |
Teuchos::RCP < StepperRKObserverComposite < Scalar > > | stepperObserver_ |
Protected Attributes inherited from Tempus::StepperImplicit< Scalar > | |
Teuchos::RCP < WrapperModelEvaluator < Scalar > > | wrapperModel_ |
Teuchos::RCP < Thyra::NonlinearSolverBase < Scalar > > | solver_ |
Teuchos::RCP< const Thyra::VectorBase< Scalar > > | initial_guess_ |
bool | zeroInitialGuess_ |
Teuchos::RCP< StepperObserver < Scalar > > | stepperObserver_ |
Teuchos::RCP < Thyra::VectorBase< Scalar > > | stepperXDot_ |
Teuchos::RCP < Thyra::VectorBase< Scalar > > | stepperXDotDot_ |
Implicit-Explicit Runge-Kutta (IMEX-RK) time stepper.
For the implicit ODE system, , we need to specialize this in order to separate the explicit, implicit, and temporal terms for the IMEX-RK time stepper,
where , is the mass matrix, is the operator representing the "slow" physics (and is evolved explicitly), and is the operator representing the "fast" physics (and is evolved implicitly). Additionally, we assume that the mass matrix is invertible, so that
where , and . Using Butcher tableaus for the explicit terms
the basic IMEX-RK method for -stages can be written as
where and . For iterative solvers, it is useful to write the stage solutions as
where
Rearranging to solve for the implicit term
We can use this to determine the time derivative at each stage for the implicit solve.
Note that the explicit term, , is evaluated at the implicit stage time, . We can form the time derivative
Returning to the governing equation
Recall and if we define a pseudo time derivative,
we can write
For the case when , we need the time derivative for the plain explicit case. Thus the stage solution is
and 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, .
IMEX-RK Algorithm
The single-timestep algorithm for IMEX-RK using the real time derivative, , is
The single-timestep algorithm for IMEX-RK using the pseudo time derivative, , is (which is currently implemented)
The following table contains the pre-coded IMEX-RK tableaus.
Name | Order | Implicit Tableau | Explicit Tableau |
---|---|---|---|
IMEX RK 1st order | 1st |
|
|
IMEX RK SSP2 | 2nd |
|
|
IMEX RK ARS 233 | 3rd |
|
|
The First-Step-As-Last (FSAL) principle is not valid for IMEX RK. The default is to set useFSAL=false, and useFSAL=true will result in an error.
Definition at line 228 of file Tempus_StepperIMEX_RK_decl.hpp.
Tempus::StepperIMEX_RK< Scalar >::StepperIMEX_RK | ( | ) |
Default constructor.
Requires subsequent setModel(), setSolver() and initialize() calls before calling takeStep().
Definition at line 27 of file Tempus_StepperIMEX_RK_impl.hpp.
Tempus::StepperIMEX_RK< Scalar >::StepperIMEX_RK | ( | const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > & | appModel, |
const Teuchos::RCP< StepperObserver< Scalar > > & | obs, | ||
const Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > & | solver, | ||
bool | useFSAL, | ||
std::string | ICConsistency, | ||
bool | ICConsistencyCheck, | ||
bool | zeroInitialGuess, | ||
std::string | stepperType, | ||
Teuchos::RCP< const RKButcherTableau< Scalar > > | explicitTableau, | ||
Teuchos::RCP< const RKButcherTableau< Scalar > > | implicitTableau, | ||
Scalar | order | ||
) |
Constructor to specialize Stepper parameters.
Definition at line 41 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Definition at line 634 of file Tempus_StepperIMEX_RK_impl.hpp.
void Tempus::StepperIMEX_RK< 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 472 of file Tempus_StepperIMEX_RK_impl.hpp.
void Tempus::StepperIMEX_RK< Scalar >::evalImplicitModelExplicitly | ( | const Teuchos::RCP< const Thyra::VectorBase< Scalar > > & | X, |
Scalar | time, | ||
Scalar | stepSize, | ||
Scalar | stageNumber, | ||
const Teuchos::RCP< Thyra::VectorBase< Scalar > > & | G | ||
) | const |
Definition at line 440 of file Tempus_StepperIMEX_RK_impl.hpp.
|
inlinevirtual |
Return alpha = d(xDot)/dx.
Implements Tempus::StepperImplicit< Scalar >.
Definition at line 314 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Return beta = d(x)/dx.
Implements Tempus::StepperImplicit< Scalar >.
Definition at line 320 of file Tempus_StepperIMEX_RK_decl.hpp.
|
virtual |
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 625 of file Tempus_StepperIMEX_RK_impl.hpp.
|
inlinevirtual |
Reimplemented from Tempus::Stepper< Scalar >.
Definition at line 340 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Reimplemented from Tempus::StepperImplicit< Scalar >.
Definition at line 271 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Get Observer.
Implements Tempus::Stepper< Scalar >.
Definition at line 284 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 299 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 301 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 300 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 310 of file Tempus_StepperIMEX_RK_decl.hpp.
|
virtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 649 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Initialize during construction and after changing input parameters.
Implements Tempus::Stepper< Scalar >.
Definition at line 363 of file Tempus_StepperIMEX_RK_impl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 303 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 305 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 304 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 308 of file Tempus_StepperIMEX_RK_decl.hpp.
|
inlinevirtual |
Implements Tempus::Stepper< Scalar >.
Definition at line 307 of file Tempus_StepperIMEX_RK_decl.hpp.
|
virtual |
Set the explicit tableau from tableau.
Definition at line 241 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Set the implicit tableau from tableau.
Definition at line 253 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Set the initial conditions and make them consistent.
Reimplemented from Tempus::StepperImplicit< Scalar >.
Definition at line 393 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Reimplemented from Tempus::StepperImplicit< Scalar >.
Definition at line 264 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
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 291 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
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 319 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Set Observer.
Implements Tempus::Stepper< Scalar >.
Definition at line 332 of file Tempus_StepperIMEX_RK_impl.hpp.
|
inline |
Definition at line 342 of file Tempus_StepperIMEX_RK_decl.hpp.
|
virtual |
Set both the explicit and implicit tableau from ParameterList.
Definition at line 75 of file Tempus_StepperIMEX_RK_impl.hpp.
|
virtual |
Take the specified timestep, dt, and return true if successful.
Implements Tempus::Stepper< Scalar >.
Definition at line 507 of file Tempus_StepperIMEX_RK_impl.hpp.
|
protected |
Definition at line 346 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 347 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 349 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 352 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 353 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 351 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 357 of file Tempus_StepperIMEX_RK_decl.hpp.
|
protected |
Definition at line 355 of file Tempus_StepperIMEX_RK_decl.hpp.