ComposeTimeStepperAction
Add the composition time stepper if multiple time steppers have been created.
This action specifies the CompositionDT object when multiple time steppers are provided in the [TimeSteppers]
block. If there are more than one time steppers provided, it will add a CompositionDT in the time stepper system and make the CompositionDT as the final time stepper to use in the transient simulations. An optional parameter "lower_bound" is provided to set a lower bound for the computed time step size. It can be specified with any time stepper(s) in the [TimeSteppers]
block.
An example of using a growing lower bound to limit the time step size as:
[Executioner<<<{"href": "../../syntax/Executioner/index.html"}>>>]
type = Transient
end_time = 0.8
solve_type = PJFNK
petsc_options_iname = '-pc_type -pc_hypre_type'
petsc_options_value = 'hypre boomeramg'
[TimeSteppers<<<{"href": "../../syntax/Executioner/TimeSteppers/index.html"}>>>]
lower_bound<<<{"description": "The maximum of these TimeSteppers will form the lower bound on the time step size. A single or multiple time steppers may be specified."}>>> = 'LogConstDT'
[ConstDT1]
type = ConstantDT<<<{"description": "Timestepper that takes a constant time step size", "href": "../timesteppers/ConstantDT.html"}>>>
dt<<<{"description": "Size of the time step"}>>> = 0.2
[]
[ConstDT2]
type = ConstantDT<<<{"description": "Timestepper that takes a constant time step size", "href": "../timesteppers/ConstantDT.html"}>>>
dt<<<{"description": "Size of the time step"}>>> = 0.1
[]
[LogConstDT]
type = LogConstantDT<<<{"description": "TimeStepper which imposes a time step constant in the logarithmic space", "href": "../timesteppers/LogConstantDT.html"}>>>
log_dt<<<{"description": "Time step in log10(time)"}>>> = 2
first_dt<<<{"description": "Initial time step (in absolute time)"}>>> = 0.01
[]
[]
[]
(moose/test/tests/time_steppers/time_stepper_system/lower_bound.i)More information about Time Stepper System and CompositionDT time stepper may be found on the Time Stepper System syntax documentation.