ChangeOverTimePostprocessor

Description

This post-processor computes the change or relative change in a post-processor value over a time step or over the entire transient. The change is computed as $(1)var element = document.getElementById("moose-equation-39148e8e-11af-46a1-af10-89081169ffa6");katex.render(" (\\Delta y)^n = y^n - y_{ref} \\,,", element, {displayMode:true,throwOnError:false});$ where $var element = document.getElementById("moose-equation-7519cf55-ffb9-4aa2-b3c9-c958f47e254f");katex.render("(\\Delta y)^n", element, {displayMode:false,throwOnError:false});$ is the relative change at time index $var element = document.getElementById("moose-equation-6192ac2d-aec1-40c3-bdf5-966d79247c69");katex.render("n", element, {displayMode:false,throwOnError:false});$ , $var element = document.getElementById("moose-equation-88b444c1-47b3-4a2a-a7e6-2576f6cb6228");katex.render("y^n", element, {displayMode:false,throwOnError:false});$ is the value of post-processor $var element = document.getElementById("moose-equation-00f1fbc7-cd19-4213-bdf9-96d483f25157");katex.render("y", element, {displayMode:false,throwOnError:false});$ at time index $var element = document.getElementById("moose-equation-c8b32756-74c6-44f1-93e7-3bb2da6979ca");katex.render("n", element, {displayMode:false,throwOnError:false});$ , and $var element = document.getElementById("moose-equation-877362cb-cef0-4ffb-ae50-a9ab899b9303");katex.render("y_{ref}", element, {displayMode:false,throwOnError:false});$ is the reference value for the change (either the previous time value, $var element = document.getElementById("moose-equation-e7b56139-f0b7-43d7-8bb8-0e26d8898ac6");katex.render("y^{n-1}", element, {displayMode:false,throwOnError:false});$ , or the initial value, $var element = document.getElementById("moose-equation-f327d5f6-2f25-49e4-a120-c38223fa9fae");katex.render("y^0", element, {displayMode:false,throwOnError:false});$ . Relative change is computed as $(2)var element = document.getElementById("moose-equation-e3f7f0ad-f65e-4a31-9f72-9819fd1b6647");katex.render(" (\\Delta y)^n = \\frac{y^n - y_{ref}}{y_{ref}} \\,.", element, {displayMode:true,throwOnError:false});$ Optionally, the user may specify to return the absolute value of the change.

Example Syntax

The following example demonstrates how this post-processor is used:

# This test tests the ChangeOverTimePostprocessor, which computes the change
# in a postprocessor value with respect to the previous value or with respect to
# the initial value. This test creates a time-dependent function postprocessor
# and then computes its change over a timestep. The FE problem used here is a
# dummy problem and has no effect on the test.

[Mesh]
  type = GeneratedMesh
  dim = 1
  nx = 5
[]

[Variables]
  [./u]
  [../]
[]

[Kernels]
  [./time_derivative]
    type = TimeDerivative
    variable = u
  [../]
  [./diff]
    type = Diffusion
    variable = u
  [../]
[]

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

[Executioner]
  type = Transient

  start_time = 0.0
  dt = 1.0
  num_steps = 2
[]

[Functions]
  [./my_function]
    type = ParsedFunction
    value = '1 + t * t'
  [../]
[]

[Postprocessors]
  [./my_postprocessor]
    type = FunctionValuePostprocessor
    function = my_function
    execute_on = 'initial timestep_end'
  [../]
  [./change_over_time]
    type = ChangeOverTimePostprocessor
    postprocessor = my_postprocessor
    change_with_respect_to_initial = false
    execute_on = 'initial timestep_end'
  [../]
[]

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

Input Parameters

postprocessorThe name of the postprocessor
C++ Type:PostprocessorName
Description:The name of the postprocessor

Required Parameters

execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.
take_absolute_valueFalseOption to take absolute value of change
Default:False
C++ Type:bool
Description:Option to take absolute value of change
compute_relative_changeFalseCompute magnitude of relative change instead of change
Default:False
C++ Type:bool
Description:Compute magnitude of relative change instead of change
change_with_respect_to_initialFalseCompute change with respect to initial value instead of previous value
Default:False
C++ Type:bool
Description:Compute change with respect to initial value instead of previous value

Optional Parameters

enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Description:Set the enabled status of the MooseObject.
use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False
C++ Type:bool
Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
outputsVector of output names were you would like to restrict the output of variables(s) associated with this object
C++ Type:std::vector
Description:Vector of output names were you would like to restrict the output of variables(s) associated with this object
control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector
Description:Adds user-defined labels for accessing object parameters via control logic.
allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
Default:False
C++ Type:bool
Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
force_preauxFalseForces the GeneralUserObject to be executed in PREAUX
Default:False
C++ Type:bool
Description:Forces the GeneralUserObject to be executed in PREAUX

Advanced Parameters

Description
Example Syntax
Input Parameters