RelativeDifferencePostprocessor

Description

This post-processor computes the absolute value of the relative difference between 2 post-processor values: $(1)var element = document.getElementById("moose-equation-1ae2d053-4404-469b-83e9-97990badf6d2");katex.render(" y = \\left| \\frac{x_1 - x_2}{x_1} \\right| \\,,", element, {displayMode:true,throwOnError:false});$ where $var element = document.getElementById("moose-equation-e130801a-5115-48fa-bfc0-9b31e8abf32c");katex.render("x_1", element, {displayMode:false,throwOnError:false});$ and $var element = document.getElementById("moose-equation-12f42ead-69af-4d2c-9888-956cef2e2cf4");katex.render("x_2", element, {displayMode:false,throwOnError:false});$ are the 2 post-processor values. Note that $var element = document.getElementById("moose-equation-8544d487-16bc-4b73-9da3-8313a76c5cd3");katex.render("x_2", element, {displayMode:false,throwOnError:false});$ is used as the base for the relative difference. If $var element = document.getElementById("moose-equation-3864551d-b3f0-47da-9b50-7343ebf78bc4");katex.render("x_2 \\approx 0", element, {displayMode:false,throwOnError:false});$ , then the absolute difference is used instead to prevent division by zero: $(2)var element = document.getElementById("moose-equation-67e0a4c7-49eb-451c-b5b9-e3379721acb1");katex.render(" y = \\left| x_1 - x_2 \\right| \\,.", element, {displayMode:true,throwOnError:false});$

Example Syntax

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

# Tests the RelativeDifferencePostprocessor post-processor, which computes
# the relative difference between 2 post-processor values.

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

[Problem]
  solve = false
[]

[Executioner]
  type = Steady
[]

[Postprocessors]
  [./num_elems]
    # number of elements, equal to 2
    type = NumElems
  [../]
  [./num_nodes]
    # number of nodes, equal to 3
    type = NumNodes
  [../]
  [./zero]
    # zero post-processor value
    type = EmptyPostprocessor
  [../]

  # For the case in this input file, this will be computed as
  #   y = abs((num_nodes - num_elems) / num_elems)
  #   y = abs((3         - 2        ) / 2        ) = 0.5
  # When the command-line modification "Postprocessors/relative_difference/value2=zero" is used,
  #   y = abs(num_nodes - zero)
  #   y = abs(3         - 0   ) = 3
  [./relative_difference]
    type = RelativeDifferencePostprocessor
    value1 = num_nodes
    value2 = num_elems
  [../]
[]

[Outputs]
  [./out]
    type = CSV
    show = relative_difference
  [../]
[]

Input Parameters

value2Second post-processor, base for relative difference
C++ Type:PostprocessorName
Description:Second post-processor, base for relative difference
value1First post-processor
C++ Type:PostprocessorName
Description:First post-processor

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.

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