TimeSequenceStepper

This time stepper derives from TimeSequenceStepperBase and provides the sequence of time values from a user-specified list, given by "time_sequence".

See Failed solves for information on the behavior of this time stepper for failed time steps.

Example input syntax

In this example, the numerical problem is solved at four specified points in time using a TimeSequenceStepper.

[Executioner]
  type = Transient
  end_time = 4.0
  [./TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '0   0.85 1.3 2 4'
  [../]
[]

Input Parameters

time_sequenceThe values of t
C++ Type:std::vector<double>
Controllable:No
Description:The values of t

Required Parameters

cutback_factor_at_failure0.5Factor to apply to timestep if a time step fails to converge.
Default:0.5
C++ Type:double
Controllable:No
Description:Factor to apply to timestep if a time step fails to converge.
reset_dtFalseUse when restarting a calculation to force a change in dt.
Default:False
C++ Type:bool
Controllable:No
Description:Use when restarting a calculation to force a change in dt.
use_last_dt_after_last_tFalseIf true, uses the final time step size for times after the last time in the sequence, instead of taking a single step directly to the simulation end time
Default:False
C++ Type:bool
Controllable:No
Description:If true, uses the final time step size for times after the last time in the sequence, instead of taking a single step directly to the simulation end time

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTruewhether or not to enable the time stepper
Default:True
C++ Type:bool
Controllable:Yes
Description:whether or not to enable the time stepper

Advanced Parameters

Input Files

(test/tests/time_steppers/timesequence_stepper/timesequence_restart3.i)
(test/tests/time_steppers/time_stepper_system/timestepper_input_error.i)
(test/tests/time_steppers/timesequence_stepper/timesequence_restart_failure.i)
(test/tests/time_steppers/timesequence_stepper/timesequence_last_dt.i)
(test/tests/time_steppers/timesequence_stepper/timesequence.i)
(test/tests/time_steppers/timesequence_stepper/timesequence_restart2.i)
(test/tests/time_steppers/timesequence_stepper/timesequence_restart1.i)
(test/tests/time_steppers/time_stepper_system/time_stepper_system.i)
(modules/optimization/test/tests/executioners/transient_and_adjoint/nonuniform_tstep.i)
(test/tests/time_steppers/time_stepper_system/multiple_timesequences.i)
(test/tests/time_steppers/time_stepper_system/multiple_timesteppers.i)
(test/tests/time_steppers/time_stepper_system/time_stepper_system_restart.i)
(modules/phase_field/test/tests/misc/timestepmaterial.i)

Child Objects

(test/include/timesteppers/TimeSequenceStepperFailTest.h)

(test/tests/time_steppers/timesequence_stepper/timesequence.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax =  1
  ymin = -1
  ymax =  1
  nx = 2
  ny = 2
  elem_type = QUAD9
[]

[Functions]
  [./exact_fn]
    type = ParsedFunction
    expression = t*t*(x*x+y*y)
  [../]

  [./forcing_fn]
    type = ParsedFunction
    expression = 2*t*(x*x+y*y)-4*t*t
  [../]
[]

[Variables]
  [./u]
    family = LAGRANGE
    order = SECOND
  [../]
[]

[ICs]
  [./u_var]
    type = FunctionIC
    variable = u
    function = exact_fn
  [../]
[]

[Kernels]
  [./td]
    type = TimeDerivative
    variable = u
  [../]

  [./diff]
    type = Diffusion
    variable = u
  [../]

  [./ffn]
    type = BodyForce
    variable = u
    function = forcing_fn
  [../]
[]

[BCs]
  [./all]
    type = FunctionDirichletBC
    variable = u
    boundary = 'left right top bottom'
    function = exact_fn
  [../]
[]

[Executioner]
  type = Transient
  end_time = 4.0
  [./TimeStepper]
    type = TimeSequenceStepper
    time_sequence  = '0   0.85 1.3 2 4'
  [../]
[]

[Outputs]
  exodus = true
[]

(test/tests/time_steppers/timesequence_stepper/timesequence_restart3.i)

[Mesh]
  file = timesequence_restart1_cp/0002-mesh.cpr
[]

[Problem]
  restart_file_base = timesequence_restart1_cp/0002
  # There is an initial conditions overwriting the restart on the nonlinear variable u
  # As you can see in the gold file, this makes the initial step output be from the
  # initial condition
  allow_initial_conditions_with_restart = true
[]

[Functions]
  [exact_fn]
    type = ParsedFunction
    expression = t*t*(x*x+y*y)
  []

  [forcing_fn]
    type = ParsedFunction
    expression = 2*t*(x*x+y*y)-4*t*t
  []
[]

[Variables]
  [u]
    family = LAGRANGE
    order = SECOND
  []
[]

[ICs]
  [u_var]
    type = FunctionIC
    variable = u
    function = exact_fn
  []
[]

[Kernels]
  [td]
    type = TimeDerivative
    variable = u
  []

  [diff]
    type = Diffusion
    variable = u
  []

  [ffn]
    type = BodyForce
    variable = u
    function = forcing_fn
  []
[]

[BCs]
  [all]
    type = FunctionDirichletBC
    variable = u
    boundary = 'left right top bottom'
    function = exact_fn
  []
[]

[Executioner]
  type = Transient
  end_time = 4.5
  [TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '0   0.85 1.3 1.9 2 4 4.5'
  []
[]

[Outputs]
  exodus = true
[]

(test/tests/time_steppers/time_stepper_system/timestepper_input_error.i)

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

[Variables]
  [u]
  []
[]

[Kernels]
  [diff]
    type = CoefDiffusion
    variable = u
    coef = 0.1
  []
  [time]
    type = TimeDerivative
    variable = u
  []
[]

[BCs]
  [left]
    type = DirichletBC
    variable = u
    boundary = left
    value = 0
  []
  [right]
    type = DirichletBC
    variable = u
    boundary = right
    value = 1
  []
[]

[Executioner]
  type = Transient   # Here we use the Transient Executioner
  [TimeSteppers]
      type = TimeSequenceStepper
      time_sequence  = '0 43200 86400 172800 432000 864000'
  []
  start_time = 0.0
  end_time = 864000
[]

[Postprocessors]
  [timestep]
    type = TimePostprocessor
    execute_on = 'timestep_end'
  []
[]

[Outputs]
  csv = true
  file_base='multiple_timesequence'
[]

(test/tests/time_steppers/timesequence_stepper/timesequence_restart_failure.i)

[Mesh]
  file = timesequence_restart_failure1_cp/0002-mesh.cpr
[]

[Problem]
  restart_file_base = timesequence_restart_failure1_cp/0002
  # There is an initial conditions overwriting the restart on the nonlinear variable u
  # As you can see in the gold file, this makes the initial step output be from the
  # initial condition
  allow_initial_conditions_with_restart = true
[]

[Functions]
  [exact_fn]
    type = ParsedFunction
    expression = t*t*(x*x+y*y)
  []

  [forcing_fn]
    type = ParsedFunction
    expression = 2*t*(x*x+y*y)-4*t*t
  []
[]

[Variables]
  [u]
    family = LAGRANGE
    order = SECOND
  []
[]

[ICs]
  [u_var]
    type = FunctionIC
    variable = u
    function = exact_fn
  []
[]

[Kernels]
  [td]
    type = TimeDerivative
    variable = u
  []

  [diff]
    type = Diffusion
    variable = u
  []

  [ffn]
    type = BodyForce
    variable = u
    function = forcing_fn
  []
[]

[BCs]
  [all]
    type = FunctionDirichletBC
    variable = u
    boundary = 'left right top bottom'
    function = exact_fn
  []
[]

[Executioner]
  type = Transient
  end_time = 4.0
  [TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '0   0.85 1.2 1.3 2 4'
  []
[]

[Outputs]
  exodus = true
[]

(test/tests/time_steppers/timesequence_stepper/timesequence_last_dt.i)

[Mesh]
  type = GeneratedMesh
  dim = 1
[]

[Problem]
  solve = false
[]

[Executioner]
  type = Transient
  num_steps = 6
  [TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '0 1 3 4 8'
    use_last_dt_after_last_t = true
  []
[]

[Postprocessors]
  [dt]
    type = TimestepSize
  []
[]

[Outputs]
  csv = true
[]

(test/tests/time_steppers/timesequence_stepper/timesequence.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax =  1
  ymin = -1
  ymax =  1
  nx = 2
  ny = 2
  elem_type = QUAD9
[]

[Functions]
  [./exact_fn]
    type = ParsedFunction
    expression = t*t*(x*x+y*y)
  [../]

  [./forcing_fn]
    type = ParsedFunction
    expression = 2*t*(x*x+y*y)-4*t*t
  [../]
[]

[Variables]
  [./u]
    family = LAGRANGE
    order = SECOND
  [../]
[]

[ICs]
  [./u_var]
    type = FunctionIC
    variable = u
    function = exact_fn
  [../]
[]

[Kernels]
  [./td]
    type = TimeDerivative
    variable = u
  [../]

  [./diff]
    type = Diffusion
    variable = u
  [../]

  [./ffn]
    type = BodyForce
    variable = u
    function = forcing_fn
  [../]
[]

[BCs]
  [./all]
    type = FunctionDirichletBC
    variable = u
    boundary = 'left right top bottom'
    function = exact_fn
  [../]
[]

[Executioner]
  type = Transient
  end_time = 4.0
  [./TimeStepper]
    type = TimeSequenceStepper
    time_sequence  = '0   0.85 1.3 2 4'
  [../]
[]

[Outputs]
  exodus = true
[]

(test/tests/time_steppers/timesequence_stepper/timesequence_restart2.i)

[Mesh]
  file = timesequence_restart1_cp/0002-mesh.cpr
[]

[Problem]
  restart_file_base = timesequence_restart1_cp/0002
  # There is an initial conditions overwriting the restart on the nonlinear variable u
  # As you can see in the gold file, this makes the initial step output be from the
  # initial condition
  allow_initial_conditions_with_restart = true
[]

[Functions]
  [exact_fn]
    type = ParsedFunction
    expression = t*t*(x*x+y*y)
  []

  [forcing_fn]
    type = ParsedFunction
    expression = 2*t*(x*x+y*y)-4*t*t
  []
[]

[Variables]
  [u]
    family = LAGRANGE
    order = SECOND
  []
[]

[ICs]
  [u_var]
    type = FunctionIC
    variable = u
    function = exact_fn
  []
[]

[Kernels]
  [td]
    type = TimeDerivative
    variable = u
  []

  [diff]
    type = Diffusion
    variable = u
  []

  [ffn]
    type = BodyForce
    variable = u
    function = forcing_fn
  []
[]

[BCs]
  [all]
    type = FunctionDirichletBC
    variable = u
    boundary = 'left right top bottom'
    function = exact_fn
  []
[]

[Executioner]
  type = Transient
  end_time = 4.0
  [TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '0   0.85 1.3 2 4'
  []
[]

[Outputs]
  exodus = true
[]

(test/tests/time_steppers/timesequence_stepper/timesequence_restart1.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax =  1
  ymin = -1
  ymax =  1
  nx = 2
  ny = 2
  elem_type = QUAD9
[]

[Functions]
  [./exact_fn]
    type = ParsedFunction
    expression = t*t*(x*x+y*y)
  [../]

  [./forcing_fn]
    type = ParsedFunction
    expression = 2*t*(x*x+y*y)-4*t*t
  [../]
[]

[Variables]
  [./u]
    family = LAGRANGE
    order = SECOND
  [../]
[]

[ICs]
  [./u_var]
    type = FunctionIC
    variable = u
    function = exact_fn
  [../]
[]

[Kernels]
  [./td]
    type = TimeDerivative
    variable = u
  [../]

  [./diff]
    type = Diffusion
    variable = u
  [../]

  [./ffn]
    type = BodyForce
    variable = u
    function = forcing_fn
  [../]
[]

[BCs]
  [./all]
    type = FunctionDirichletBC
    variable = u
    boundary = 'left right top bottom'
    function = exact_fn
  [../]
[]

[Executioner]
  type = Transient
  end_time = 4.0
  [./TimeStepper]
    type = TimeSequenceStepper
    time_sequence  = '0   0.85 1.3 2 4'
  [../]
[]

[Outputs]
  exodus = true
  [./checkpoint]
    type = Checkpoint
    num_files = 4
  [../]
[]

(test/tests/time_steppers/time_stepper_system/time_stepper_system.i)

[Mesh]
  file = restart_test_cp/0005-mesh.cpr
[]

[Variables]
  [u]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[Problem]
   type = SlowProblem
   seconds_to_sleep = '0.0 0.0 0.1 0.1 0.5 0.2 0.2 0.1 0.1 0.1'
   kernel_coverage_check = false
  restart_file_base = restart_test_cp/0005
[]

[Executioner]
  type = Transient
  solve_type = NEWTON
  num_steps = 10

  [TimeSteppers]
    [LogConstDT]
      type = LogConstantDT
      log_dt = 0.2
      first_dt = 0.1
    []

    [Timesequence]
      type = TimeSequenceStepper
      time_sequence  = '0  0.12 0.2 0.5 0.6'
    []
  []
[]

[Postprocessors]
  [dt]
    type = TimestepSize
  []
[]

[Outputs]
  csv = true
  file_base='time_stepper_restart'
[]

(modules/optimization/test/tests/executioners/transient_and_adjoint/nonuniform_tstep.i)

[Mesh]
  [gmg]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymax = 1
    nx = 10
    ny = 10
  []
[]

[Problem]
  nl_sys_names = 'nl0 adjoint'
[]

[Variables]
  [u]
  []
  [u_adjoint]
    solver_sys = adjoint
  []
[]

[Kernels]
  [time]
    type = TimeDerivative
    variable = u
  []
  [diff]
    type = Diffusion
    variable = u
  []
  [src]
    type = BodyForce
    variable = u
    value = 10
  []
  [src_adjoint]
    type = BodyForce
    variable = u_adjoint
    value = 100
  []
[]

[BCs]
  [dirichlet]
    type = DirichletBC
    variable = u
    boundary = 'top right'
    value = 0
  []
[]

[Executioner]
  type = TransientAndAdjoint
  forward_system = nl0
  adjoint_system = adjoint

  [TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '0 0.1 0.2 0.4 0.7 1.1 1.4 1.6 1.7'
  []
  end_time = 1.7

  nl_rel_tol = 1e-12
  l_tol = 1e-12
[]

[Postprocessors]
  [u_avg]
    type = ElementAverageValue
    variable = u
    execute_on = 'TIMESTEP_END ADJOINT_TIMESTEP_END'
  []
  [u_adjoint_avg]
    type = ElementAverageValue
    variable = u_adjoint
    execute_on = ADJOINT_TIMESTEP_END
  []
  [inner_product]
    type = VariableInnerProduct
    variable = u
    second_variable = u_adjoint
    execute_on = ADJOINT_TIMESTEP_END
  []
[]

[Outputs]
  [forward]
    type = CSV
  []
  [adjoint]
    type = CSV
    execute_on = 'INITIAL ADJOINT_TIMESTEP_END'
  []
  [console]
    type = Console
    execute_postprocessors_on = 'INITIAL TIMESTEP_END ADJOINT_TIMESTEP_END'
  []
[]

(test/tests/time_steppers/time_stepper_system/multiple_timesequences.i)

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

[Variables]
  [u]
  []
[]

[Kernels]
  [diff]
    type = CoefDiffusion
    variable = u
    coef = 0.1
  []
  [time]
    type = TimeDerivative
    variable = u
  []
[]

[BCs]
  [left]
    type = DirichletBC
    variable = u
    boundary = left
    value = 0
  []
  [right]
    type = DirichletBC
    variable = u
    boundary = right
    value = 1
  []
[]

[Executioner]
  type = Transient
  end_time = 0.8
  solve_type = PJFNK
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
  # Use as many different time sequence steppers as we could to test the compositionDT
  [TimeSteppers]
    [ConstDT1]
      type = ConstantDT
      dt = 0.2
    []

    [ConstDT2]
      type = ConstantDT
      dt = 0.1
    []

    [LogConstDT]
      type = LogConstantDT
      log_dt = 0.2
      first_dt = 0.1
    []

    [Timesequence1]
      type = TimeSequenceStepper
      time_sequence  = '0  0.25 0.3 0.5 0.8'
    []

    [Timesequence2]
      type = CSVTimeSequenceStepper
      file_name = timesequence.csv
      column_name = time
    []

    [Timesequence3]
      type = ExodusTimeSequenceStepper
      mesh = timesequence.e
    []
  []
[]

[Postprocessors]
  [timestep]
    type = TimePostprocessor
    execute_on = 'timestep_end'
  []
[]

[Outputs]
  csv = true
  file_base='multiple_timesequences'
[]

(test/tests/time_steppers/time_stepper_system/multiple_timesteppers.i)

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

[Variables]
  [u]
  []
[]

[Kernels]
  [diff]
    type = CoefDiffusion
    variable = u
    coef = 0.1
  []
  [time]
    type = TimeDerivative
    variable = u
  []
[]

[Functions]
  [dts]
    type = PiecewiseLinear
    x = '0   0.85 2'
    y = '0.2 0.15  0.2'
  []
[]

[BCs]
  [left]
    type = DirichletBC
    variable = u
    boundary = left
    value = 0
  []
  [right]
    type = DirichletBC
    variable = u
    boundary = right
    value = 1
  []
[]

[Executioner]
  type = Transient
  end_time = 0.8
  solve_type = PJFNK
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
  # Use as many different time steppers as we could to test the compositionDT,
  # SolutionTimeAdaptiveDT give slightly different dt per run, set rel_err = 1e-2
  # to ensure the test won't fail due to the small difference in the high-digit.
  [TimeSteppers]
    [ConstDT1]
      type = ConstantDT
      dt = 0.2
    []

    [FunctionDT]
      type = FunctionDT
      function = dts
    []

    [LogConstDT]
      type = LogConstantDT
      log_dt = 0.2
      first_dt = 0.1
    []

    [IterationAdapDT]
      type = IterationAdaptiveDT
      dt = 0.5
    []

    [Timesequence]
      type = TimeSequenceStepper
      time_sequence  = '0  0.25 0.3 0.5 0.8'
    []

    [PPDT]
      type = PostprocessorDT
      postprocessor = PostDT
      dt = 0.1
    []
  []
[]

[Postprocessors]
  [timestep]
    type = TimePostprocessor
    execute_on = 'timestep_end'
  []

  [PostDT]
    type = ElementAverageValue
    variable = u
    execute_on = 'initial timestep_end'
  []
[]

[Outputs]
  csv = true
  file_base='multiple_timesteppers'
[]

(test/tests/time_steppers/time_stepper_system/time_stepper_system_restart.i)

[Mesh]
  type = GeneratedMesh
  dim = 1
[]

[Variables]
  [u]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[Problem]
   type = SlowProblem
   seconds_to_sleep = '0.0 0.0 0.1 0.1 0.5 0.2 0.2 0.1 0.1 0.1'
   kernel_coverage_check = false
[]

[Executioner]
  type = Transient
  solve_type = NEWTON
  num_steps = 5

  [TimeSteppers]
    [SolutionTimeAdaptiveDT]
      type = SolutionTimeAdaptiveDT
      dt = 0.5
    []

    [LogConstDT]
      type = LogConstantDT
      log_dt = 0.2
      first_dt = 0.1
    []

    [Timesequence]
      type = TimeSequenceStepper
      time_sequence  = '0  0.12 0.2 0.5 0.6'
    []
  []
[]

[Postprocessors]
  [dt]
    type = TimestepSize
  []
[]

[Outputs]
  [checkpoint]
    type = Checkpoint
    num_files = 5
  []
  file_base='restart_test'
[]

(modules/phase_field/test/tests/misc/timestepmaterial.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 2
  ny = 1
[]

[Materials]
  [./time]
    type = TimeStepMaterial
    outputs = exodus
  [../]
[]

[Problem]
  solve = false
  kernel_coverage_check = false
[]

[Executioner]
  type = Transient
  num_steps = 6

  [./TimeStepper]
    type = TimeSequenceStepper
    time_sequence = '4 8 15 16 23 42'
  [../]
[]

[Outputs]
  exodus = true
  execute_on = timestep_end
[]

(test/include/timesteppers/TimeSequenceStepperFailTest.h)

// This file is part of the MOOSE framework
// https://www.mooseframework.org
//
// All rights reserved, see COPYRIGHT for full restrictions
// https://github.com/idaholab/moose/blob/master/COPYRIGHT
//
// Licensed under LGPL 2.1, please see LICENSE for details
// https://www.gnu.org/licenses/lgpl-2.1.html

#pragma once

#include "TimeSequenceStepper.h"

/**
 * Exactly the same as TimeSequenceStepper, but fails at predetermined
 * timesteps.
 */
class TimeSequenceStepperFailTest : public TimeSequenceStepper
{
public:
  static InputParameters validParams();

  TimeSequenceStepperFailTest(const InputParameters & parameters);

  virtual void step() override;

protected:
  /// stores a copy of the original sequence of time points, is not updated due to failures.
  std::vector<Real> _original_time_sequence;
};

Example input syntax
Input Parameters
Input Files
Child Objects