Multiple Time Integrators

The time integrator system is described in TimeIntegrator System. Multiple time integrators in a single input are supported using Executioner/TimeIntegrators syntax as illustrated below:

[Executioner]
  type = Transient
  solve_type = 'NEWTON'
  petsc_options_iname = '-pc_type'
  petsc_options_value = 'hypre'
  dt = 1
  end_time = 3
  [TimeIntegrators]
    [cn]
      type = CrankNicolson
      variables = 'u'
    []
    [ie]
      type = ImplicitEuler
      variables = 'v'
    []
  []
[]

where each individual time integrator has specific variables assigned to it.

Available Objects

Moose App
AStableDirk4Fourth-order diagonally implicit Runge Kutta method (Dirk) with three stages plus an update.
ActuallyExplicitEulerImplementation of Explicit/Forward Euler without invoking any of the nonlinear solver
BDF2Second order backward differentiation formula time integration scheme.
CentralDifferenceImplementation of explicit, Central Difference integration without invoking any of the nonlinear solver
CrankNicolsonCrank-Nicolson time integrator.
ExplicitEulerTime integration using the explicit Euler method.
ExplicitMidpointTime integration using the explicit midpoint method.
ExplicitSSPRungeKuttaExplicit strong stability preserving Runge-Kutta methods
ExplicitTVDRK2Explicit TVD (total-variation-diminishing) second-order Runge-Kutta time integration method.
HeunHeun's (aka improved Euler) time integration method.
ImplicitEulerTime integration using the implicit Euler method.
ImplicitMidpointSecond-order Runge-Kutta (implicit midpoint) time integration.
LStableDirk2Second order diagonally implicit Runge Kutta method (Dirk) with two stages.
LStableDirk3Third order diagonally implicit Runge Kutta method (Dirk) with three stages.
LStableDirk4Fourth-order diagonally implicit Runge Kutta method (Dirk) with five stages.
NewmarkBetaComputes the first and second time derivative of variable using Newmark-Beta method.
RalstonRalston's time integration method.
Solid Mechanics App
DirectCentralDifferenceImplementation of Explicit/Forward Euler without invoking any of the nonlinear solver

Available Actions

Moose App
SetupTimeIntegratorActionAdd a TimeIntegrator object to the simulation.

Input Parameters

active__all__ If specified only the blocks named will be visited and made active
Default:__all__
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:If specified only the blocks named will be visited and made active
inactiveIf specified blocks matching these identifiers will be skipped.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:If specified blocks matching these identifiers will be skipped.

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
isObjectActionTrueIndicates that this is a MooseObjectAction.
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Indicates that this is a MooseObjectAction.

Advanced Parameters

(moose/test/tests/time_integrators/multiple-integrators/test.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 10
  ny = 10
[]

[Variables]
  [u][]
  [v][]
[]

[Kernels]
  [timeu]
    type = TimeDerivative
    variable = u
  []
  [timev]
    type = TimeDerivative
    variable = v
  []
  [diffu]
    type = Diffusion
    variable = u
  []
  [diffv]
    type = Diffusion
    variable = v
  []
  [forceu]
    type = BodyForce
    variable = u
    function = force
  []
  [forcev]
    type = BodyForce
    variable = v
    function = force
  []
[]

[Functions]
  [exact]
    type = ParsedFunction
    expression = 't^3*x*y'
  []
  [force]
    type = ParsedFunction
    expression = '3*x*y*t^2'
  []
[]

[BCs]
  [allu]
    type = FunctionDirichletBC
    variable = u
    function = exact
    boundary = 'left right top bottom'
  []
  [allv]
    type = FunctionDirichletBC
    variable = v
    function = exact
    boundary = 'left right top bottom'
  []
[]

[Executioner]
  type = Transient
  solve_type = 'NEWTON'
  petsc_options_iname = '-pc_type'
  petsc_options_value = 'hypre'
  dt = 1
  end_time = 3
  [TimeIntegrators]
    [cn]
      type = CrankNicolson
      variables = 'u'
    []
    [ie]
      type = ImplicitEuler
      variables = 'v'
    []
  []
[]

[Postprocessors]
  [L2u]
    type = ElementL2Error
    function = exact
    variable = u
  []
  [L2v]
    type = ElementL2Error
    function = exact
    variable = v
  []
[]

[Outputs]
  csv = true
[]