ElementVariablesDifferenceMax

Computes the largest difference between two variable fields.

This postprocessor can find the maximum of the difference or the absolute difference if the "furthest_from_zero" parameter is set to true. This vector postprocessor output to CSV has the following columns, in this order by default:

the maximum difference between the two variables
the value of variable A at the location of the maximum difference
the value of variable B at the location of the maximum difference
the first (X in Cartesian) coordinate of the location of the maximum difference
the second (Y in Cartesian) coordinate of the location of the maximum difference
the third (Z in Cartesian) coordinate of the location of the maximum difference

note:Vector names / CSV output column names

The names of the vectors declared are Difference, the name of the "compare_a" variable, the name of the "compare_b" variable, and finally X, Y, Z for the location of the maximum difference.

Example input syntax

In this example, we compare variable u and v using a ElementVariablesDifferenceMax vector postprocessor.

[VectorPostprocessors]
  [./difference]
    type = ElementVariablesDifferenceMax
    compare_a = u
    compare_b = v
  [../]
[]

Input Parameters

compare_aThe first variable to evaluate the difference with, performed as "compare_a - compare_b"
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The first variable to evaluate the difference with, performed as "compare_a - compare_b"
compare_bThe second variable to evaluate the difference with, performed as "compare_a - compare_b"
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The second variable to evaluate the difference with, performed as "compare_a - compare_b"

Required Parameters

blockThe list of blocks (ids or names) that this object will be applied
C++ Type:std::vector<SubdomainName>
Unit:(no unit assumed)
Controllable:No
Description:The list of blocks (ids or names) that this object will be applied
contains_complete_historyFalseSet this flag to indicate that the values in all vectors declared by this VPP represent a time history (e.g. with each invocation, new values are added and old values are never removed). This changes the output so that only a single file is output and updated with each invocation
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Set this flag to indicate that the values in all vectors declared by this VPP represent a time history (e.g. with each invocation, new values are added and old values are never removed). This changes the output so that only a single file is output and updated with each invocation
execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Unit:(no unit assumed)
Options:NONE, INITIAL, LINEAR, NONLINEAR_CONVERGENCE, NONLINEAR, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM
Controllable:No
Description:The list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
furthest_from_zeroFalseFind the difference with the highest absolute value
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Find the difference with the highest absolute value
parallel_typeREPLICATEDSet how the data is represented within the VectorPostprocessor (VPP); 'distributed' indicates that data within the VPP is distributed and no auto communication is performed, this setting will result in parallel output within the CSV output; 'replicated' indicates that the data within the VPP is correct on processor 0, the data will automatically be broadcast to all processors unless the '_auto_broadcast' param is set to false within the validParams function.
Default:REPLICATED
C++ Type:MooseEnum
Unit:(no unit assumed)
Options:DISTRIBUTED, REPLICATED
Controllable:No
Description:Set how the data is represented within the VectorPostprocessor (VPP); 'distributed' indicates that data within the VPP is distributed and no auto communication is performed, this setting will result in parallel output within the CSV output; 'replicated' indicates that the data within the VPP is correct on processor 0, the data will automatically be broadcast to all processors unless the '_auto_broadcast' param is set to false within the validParams function.
prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
C++ Type:MaterialPropertyName
Unit:(no unit assumed)
Controllable:No
Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.

Optional Parameters

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
Unit:(no unit assumed)
Controllable:No
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).
control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:Yes
Description:Set the enabled status of the MooseObject.
execution_order_group0Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
Default:0
C++ Type:int
Unit:(no unit assumed)
Controllable:No
Description:Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
force_postauxFalseForces the UserObject to be executed in POSTAUX
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Forces the UserObject to be executed in POSTAUX
force_preauxFalseForces the UserObject to be executed in PREAUX
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Forces the UserObject to be executed in PREAUX
force_preicFalseForces the UserObject to be executed in PREIC during initial setup
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Forces the UserObject to be executed in PREIC during initial setup
implicitTrueDetermines whether this object is calculated using an implicit or explicit form
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Determines whether this object is calculated using an implicit or explicit form
outputsVector of output names where you would like to restrict the output of variables(s) associated with this object
C++ Type:std::vector<OutputName>
Unit:(no unit assumed)
Controllable:No
Description:Vector of output names where you would like to restrict the output of variables(s) associated with this object
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Unit:(no unit assumed)
Controllable:No
Description:The seed for the master random number generator
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
Unit:(no unit assumed)
Controllable:No
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.

Advanced Parameters

(moose/test/tests/vectorpostprocessors/element_variables_difference_max/element_variables_difference_max.i)

[Mesh]
  type = GeneratedMesh
  dim = 3
  nx = 10
  ny = 10
  nz = 10
[]

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

  [./v]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Functions]
  [./forcing_v]
    type = ParsedFunction
    expression = 'x * y * z'
  [../]
[]

[Kernels]
  [./diffusion_u]
    type = Diffusion
    variable = u
  [../]
  [./time_u]
    type = TimeDerivative
    variable = u
  [../]

  [./diffusion_v]
    type = Diffusion
    variable = v
  [../]
  [./forcing_v]
    type = BodyForce
    variable = v
    function = forcing_v
  [../]
  [./time_v]
    type = TimeDerivative
    variable = v
  [../]
[]

[BCs]
  [./bottom]
    type = DirichletBC
    variable = 'u'
    boundary = 'bottom'
    value = 1
  [../]

  [./top]
    type = DirichletBC
    variable = 'u'
    boundary = 'top'
    value = 0
  [../]
[]

[VectorPostprocessors]
  [./difference]
    type = ElementVariablesDifferenceMax
    compare_a = u
    compare_b = v
  [../]
[]

[Executioner]
  type = Transient
  num_steps = 2
  dt = 1
  solve_type = PJFNK
[]

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

Example input syntax
Input Parameters