DT2

under construction:Undocumented Class

The DT2 has not been documented. The content listed below should be used as a starting point for documenting the class, which includes the typical automatic documentation associated with a MooseObject; however, what is contained is ultimately determined by what is necessary to make the documentation clear for users.


# DT2

!syntax description /Executioner/TimeStepper/DT2

## Overview

!! Replace these lines with information regarding the DT2 object.

## Example Input File Syntax

!! Describe and include an example of how to use the DT2 object.

!syntax parameters /Executioner/TimeStepper/DT2

!syntax inputs /Executioner/TimeStepper/DT2

!syntax children /Executioner/TimeStepper/DT2

!syntax description /Executioner/TimeStepper/DT2

Input Parameters

e_maxMaximum acceptable error.
C++ Type:double
Options:
Description:Maximum acceptable error.
e_tolTarget error tolerance.
C++ Type:double
Options:
Description:Target error tolerance.

Required Parameters

cutback_factor_at_failure0.5Factor to apply to timestep if it a time step fails to convergence.
Default:0.5
C++ Type:double
Options:
Description:Factor to apply to timestep if it a time step fails to convergence.
dt1The initial time step size.
Default:1
C++ Type:double
Options:
Description:The initial time step size.
max_increase1e+09Maximum ratio that the time step can increase.
Default:1e+09
C++ Type:double
Options:
Description:Maximum ratio that the time step can increase.
reset_dtFalseUse when restarting a calculation to force a change in dt.
Default:False
C++ Type:bool
Options:
Description:Use when restarting a calculation to force a change in dt.

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector
Options:
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Options:
Description:Set the enabled status of the MooseObject.

Advanced Parameters

test/tests/time_steppers/dt2/dt2_adapt.i

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax = 1
  ymin = -1
  ymax = 1
  nx = 15
  ny = 15
  elem_type = QUAD4
[]

[GlobalParams]
  slope = 1
  t_jump = 2
[]

[Variables]
  active = 'u'

  [./u]
    order = FIRST
    family = LAGRANGE

    [./InitialCondition]
      type = TEIC
    [../]
  [../]
[]

[Kernels]
  active = 'td diff ffn'

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

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

  [./ffn]
    type = TEJumpFFN
    variable = u
  [../]
[]

[BCs]
  active = 'all'

  [./all]
    type = TEJumpBC
    variable = u
    boundary = '0 1 2 3'
  [../]
[]

[Postprocessors]
  active = 'dt'

  [./dt]
    type = TimestepSize
  [../]
[]

[Executioner]
  type = Transient


  solve_type = 'PJFNK'

  nl_rel_tol = 1e-7
#  l_tol = 1e-5

  [./Adaptivity]
    refine_fraction = 0.2
    coarsen_fraction = 0.3
    max_h_level = 4
  [../]

  start_time = 0.0
  end_time = 5
  num_steps = 500000

  dtmax = 0.25

  [./TimeStepper]
    type = DT2
    dt = 0.1
    e_max = 3e-1
    e_tol = 1e-1
  [../]
[]

[Outputs]
  execute_on = 'timestep_end'
  csv = false
  exodus = true
[]

test/tests/time_steppers/dt2/dt2.i

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax = 1
  ymin = -1
  ymax = 1
  nx = 20
  ny = 20
  elem_type = QUAD4
[]

[GlobalParams]
  slope = 1
  t_jump = 2
[]

[Functions]
  active = 'u_func'

  [./u_func]
    type = ParsedFunction
    value = 'atan((t-2)*pi)'   # atan((t-t_jump)*pi*slope) - has to match global params above

  [../]
[]

[Variables]
  active = 'u'

  [./u]
    order = FIRST
    family = LAGRANGE

    [./InitialCondition]
      type = TEIC
    [../]
  [../]
[]

[Kernels]
  active = 'td diff ffn'

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

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

  [./ffn]
    type = TEJumpFFN
    variable = u
  [../]
[]

[BCs]
  active = 'all'

  [./all]
    type = TEJumpBC
    variable = u
    boundary = '0 1 2 3'
  [../]
[]

[Postprocessors]
  active = 'dt l2'

  [./dt]
    type = TimestepSize
  [../]

  [./l2]
    type = ElementL2Error
    variable = u
    function = u_func
  [../]
[]

[Executioner]
  type = Transient


  solve_type = 'PJFNK'

  nl_rel_tol = 1e-7
#  l_tol = 1e-5

  start_time = 0.0
  end_time = 5
  num_steps = 500000
  dtmax = 0.25

  [./TimeStepper]
    type = DT2
    dt = 0.1
    e_max = 3e-1
    e_tol = 1e-1
  [../]
[]

[Outputs]
  execute_on = 'timestep_end'
  csv = true
  exodus = true
[]

Input Parameters
Input Files

Application Usage

Physics and Syntax

Application Development

Framework Development

MOOSEDocs

Infrastructure

Questions

Information and Tools

DT2

Input Parameters

Required Parameters

Optional Parameters

Advanced Parameters

Input Files