NekSideExtremeValue

Compute the extreme value (max/min) of a field over a boundary of the NekRS mesh

Description

This postprocessor computes the extreme value (maximum or minimum) of a specified field over a boundary in the NekRS mesh. For value_type = max, this postprocessor computes

$var element = document.getElementById("moose-equation-03054a08-93a9-4154-86ea-6c07953fcfe0");katex.render("p=\\max_\\Gamma{f}", element, {displayMode:true,throwOnError:false});$

where $var element = document.getElementById("moose-equation-c2ec7479-8cfd-4936-a648-52c2fcbe4143");katex.render("p", element, {displayMode:false,throwOnError:false});$ is the value of the postprocessor, $var element = document.getElementById("moose-equation-de2fad28-d740-4bc1-a3a8-5a9d5993d126");katex.render("\\Gamma", element, {displayMode:false,throwOnError:false});$ is the boundary of the NekRS mesh, and $var element = document.getElementById("moose-equation-53cb2605-0c46-4a8c-bbe6-1850e092f876");katex.render("f", element, {displayMode:false,throwOnError:false});$ is the specified field. For value_type = min, this postprocessor instead computes

$var element = document.getElementById("moose-equation-e31c8e22-a488-4da2-9315-78497779e82c");katex.render("p=\\min_\\Gamma{f}", element, {displayMode:true,throwOnError:false});$

The boundaries over which to compute this postprocessor in the NekRS mesh are specified with the boundary parameter; these boundaries are the sidesets in NekRS's mesh (i.e. the .re2 file). You can specify more than one boundary, with syntax such as boundary = '1 2'. To be clear, this postprocessor is not evaluated on the NekRSMesh mesh mirror, but instead on the mesh actually used for computation in NekRS.

The field is specified with the field parameter, which may be one of:

pressure
temperature
velocity (magnitude of velocity)
velocity_x ( $var element = document.getElementById("moose-equation-ef330b56-ba81-4563-bd22-eb344a00d0a2");katex.render("x", element, {displayMode:false,throwOnError:false});$ -component of velocity)
velocity_y ( $var element = document.getElementById("moose-equation-ea7a2b5d-7608-49a7-8d6d-b99fa96e47a0");katex.render("y", element, {displayMode:false,throwOnError:false});$ -component of velocity)
velocity_z ( $var element = document.getElementById("moose-equation-3a99aa39-0752-4c44-9ef8-fbaa0cf76caa");katex.render("z", element, {displayMode:false,throwOnError:false});$ -component of velocity)
velocity_component (velocity vector projected onto another vector)
scalar01
scalar02
scalar03
unity

Setting field = unity is equivalent to computing 1, since the extreme value is also 1 (unity is of more use for other postprocessors).

If running NekRS in non-dimensional form (and you have indicated the appropriate nondimensional scales by setting nondimensional = true for the [Problem], then the value of this postprocessor is shown in dimensional units. On the otherhand, NekRS scalars (scalar01, scalar02 or scalar03) are never dimensionalized because their dimensions are problem-dependent.

Example Input Syntax

As an example, the following code snippet will evaluate the maximum and minimum temperature, pressure, velocity magnitude, and velocity components on the boundaries of the NekRS mesh.

[Postprocessors]
  [max_temp_side1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = max
  []
  [max_temp_side2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '2'
    value_type = max
  []
  [max_temp_side3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = max
  []
  [max_temp_side4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = max
  []
  [max_temp_side5]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = max
  []
  [max_temp_side6]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = max
  []
  [max_temp_side7]
    type = NekSideExtremeValue
    field = temperature
    boundary = '7'
    value_type = max
  []
  [max_temp_side8]
    type = NekSideExtremeValue
    field = temperature
    boundary = '8'
    value_type = max
  []
  [min_temp_side1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = min
  []
  [min_temp_side2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '2'
    value_type = min
  []
  [min_temp_side3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = min
  []
  [min_temp_side4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [min_temp_side5]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = min
  []
  [min_temp_side6]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = min
  []
  [min_temp_side7]
    type = NekSideExtremeValue
    field = temperature
    boundary = '7'
    value_type = min
  []
  [min_temp_side8]
    type = NekSideExtremeValue
    field = temperature
    boundary = '8'
    value_type = min
  []

  [max_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
  []
  [max_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
  []
  [max_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
  []
  [max_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
  []
  [max_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
  []
  [max_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
  []
  [max_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
  []
  [max_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
  []
  [min_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
    value_type = min
  []
  [min_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
    value_type = min
  []
  [min_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = min
  []
  [min_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
    value_type = min
  []
  [min_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
    value_type = min
  []
  [min_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
    value_type = min
  []
  [min_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
    value_type = min
  []
  [min_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
    value_type = min
  []

  [max_velocity_side1]
    type = NekSideExtremeValue
    field = velocity
    boundary = '1'
    value_type = max
  []
  [max_velocity_side2]
    type = NekSideExtremeValue
    field = velocity
    boundary = '2'
    value_type = max
  []
  [max_velocity_side3]
    type = NekSideExtremeValue
    field = velocity
    boundary = '3'
    value_type = max
  []
  [max_velocity_side4]
    type = NekSideExtremeValue
    field = velocity
    boundary = '4'
    value_type = max
  []
  [max_velocity_side5]
    type = NekSideExtremeValue
    field = velocity
    boundary = '5'
    value_type = max
  []
  [max_velocity_side6]
    type = NekSideExtremeValue
    field = velocity
    boundary = '6'
    value_type = max
  []
  [max_velocity_side7]
    type = NekSideExtremeValue
    field = velocity
    boundary = '7'
    value_type = max
  []
  [max_velocity_side8]
    type = NekSideExtremeValue
    field = velocity
    boundary = '8'
    value_type = max
  []
  [min_velocity_side1]
    type = NekSideExtremeValue
    field = velocity
    boundary = '1'
    value_type = min
  []
  [min_velocity_side2]
    type = NekSideExtremeValue
    field = velocity
    boundary = '2'
    value_type = min
  []
  [min_velocity_side3]
    type = NekSideExtremeValue
    field = velocity
    boundary = '3'
    value_type = min
  []
  [min_velocity_side4]
    type = NekSideExtremeValue
    field = velocity
    boundary = '4'
    value_type = min
  []
  [min_velocity_side5]
    type = NekSideExtremeValue
    field = velocity
    boundary = '5'
    value_type = min
  []
  [min_velocity_side6]
    type = NekSideExtremeValue
    field = velocity
    boundary = '6'
    value_type = min
  []
  [min_velocity_side7]
    type = NekSideExtremeValue
    field = velocity
    boundary = '7'
    value_type = min
  []
  [min_velocity_side8]
    type = NekSideExtremeValue
    field = velocity
    boundary = '8'
    value_type = min
  []

  [max_x_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '1'
    value_type = max
  []
  [max_x_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '2'
    value_type = max
  []
  [max_x_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '3'
    value_type = max
  []
  [max_x_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '4'
    value_type = max
  []
  [max_x_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '5'
    value_type = max
  []
  [max_x_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '6'
    value_type = max
  []
  [max_x_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '7'
    value_type = max
  []
  [max_x_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '8'
    value_type = max
  []
  [min_x_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '1'
    value_type = min
  []
  [min_x_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '2'
    value_type = min
  []
  [min_x_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '3'
    value_type = min
  []
  [min_x_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '4'
    value_type = min
  []
  [min_x_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '5'
    value_type = min
  []
  [min_x_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '6'
    value_type = min
  []
  [min_x_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '7'
    value_type = min
  []
  [min_x_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '8'
    value_type = min
  []
  [max_y_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '1'
    value_type = max
  []
  [max_y_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '2'
    value_type = max
  []
  [max_y_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '3'
    value_type = max
  []
  [max_y_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '4'
    value_type = max
  []
  [max_y_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '5'
    value_type = max
  []
  [max_y_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '6'
    value_type = max
  []
  [max_y_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '7'
    value_type = max
  []
  [max_y_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '8'
    value_type = max
  []
  [min_y_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '1'
    value_type = min
  []
  [min_y_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '2'
    value_type = min
  []
  [min_y_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '3'
    value_type = min
  []
  [min_y_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '4'
    value_type = min
  []
  [min_y_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '5'
    value_type = min
  []
  [min_y_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '6'
    value_type = min
  []
  [min_y_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '7'
    value_type = min
  []
  [min_y_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '8'
    value_type = min
  []
  [max_z_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '1'
    value_type = max
  []
  [max_z_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '2'
    value_type = max
  []
  [max_z_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '3'
    value_type = max
  []
  [max_z_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '4'
    value_type = max
  []
  [max_z_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '5'
    value_type = max
  []
  [max_z_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '6'
    value_type = max
  []
  [max_z_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '7'
    value_type = max
  []
  [max_z_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '8'
    value_type = max
  []
  [min_z_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '1'
    value_type = min
  []
  [min_z_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '2'
    value_type = min
  []
  [min_z_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '3'
    value_type = min
  []
  [min_z_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '4'
    value_type = min
  []
  [min_z_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '5'
    value_type = min
  []
  [min_z_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '6'
    value_type = min
  []
  [min_z_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '7'
    value_type = min
  []
  [min_z_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '8'
    value_type = min
  []
[]

Input Parameters

boundaryBoundary ID(s) for which to compute the postprocessor
C++ Type:std::vector<int>
Controllable:No
Description:Boundary ID(s) for which to compute the postprocessor
fieldField to integrate
C++ Type:MooseEnum
Options:velocity_component, velocity_x, velocity_y, velocity_z, velocity, temperature, pressure, scalar01, scalar02, scalar03, unity
Controllable:No
Description:Field to integrate

Required Parameters

execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Options:NONE, INITIAL, LINEAR, NONLINEAR, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, TRANSFER
Controllable:No
Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM.
meshallNekRS mesh to compute postprocessor on
Default:all
C++ Type:MooseEnum
Options:fluid, solid, all
Controllable:No
Description:NekRS mesh to compute postprocessor on
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
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
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.
value_typemaxWhether to give the maximum or minimum extreme value
Default:max
C++ Type:MooseEnum
Options:max, min, average
Controllable:No
Description:Whether to give the maximum or minimum extreme value
velocity_directionDirection in which to evaluate velocity, for 'field = velocity_component'. For example, velocity_direction = '1 0 0' will get the x-component of velocity.
C++ Type:libMesh::Point
Controllable:No
Description:Direction in which to evaluate velocity, for 'field = velocity_component'. For example, velocity_direction = '1 0 0' will get the x-component of velocity.

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
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>
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
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
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
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
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
Controllable:No
Description:Forces the UserObject to be executed in PREIC during initial setup
outputsVector of output names where you would like to restrict the output of variables(s) associated with this object
C++ Type:std::vector<OutputName>
Controllable:No
Description:Vector of output names where you would like to restrict the output of variables(s) associated with this object
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
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

Input Files

(test/tests/nek_standalone/lowMach/nek.i)
(test/tests/cht/sfr_pincell/nek_vpp.i)
(test/tests/conduction/boundary_and_volume/prism/nek.i)
(test/tests/cht/nondimensional/nek_exact.i)
(test/tests/nek_separatedomain/transfers_temperature/nek.i)
(test/tests/cht/nondimensional/nek.i)
(test/tests/nek_stochastic/device/nek_multi.i)
(test/tests/postprocessors/nek_side_extrema/nek_p.i)
(test/tests/conduction/boundary_and_volume/prism/nek_exact.i)
(test/tests/nek_standalone/lowMach/nek_boundary.i)
(test/tests/nek_standalone/channel/nek.i)
(test/tests/postprocessors/nek_side_extrema/nek.i)
(test/tests/cht/sfr_pincell/nek.i)

(test/tests/postprocessors/nek_side_extrema/nek.i)

[Problem]
  type = NekRSProblem
  casename = 'pyramid'
[]

[Mesh]
  type = NekRSMesh
  boundary = '1 2 3 4 5 6 7 8'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Outputs]
  [out]
    type = CSV
    hide = 'flux_integral'
    execute_on = 'final'
  []
[]

[Postprocessors]
  [max_temp_side1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = max
  []
  [max_temp_side2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '2'
    value_type = max
  []
  [max_temp_side3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = max
  []
  [max_temp_side4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = max
  []
  [max_temp_side5]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = max
  []
  [max_temp_side6]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = max
  []
  [max_temp_side7]
    type = NekSideExtremeValue
    field = temperature
    boundary = '7'
    value_type = max
  []
  [max_temp_side8]
    type = NekSideExtremeValue
    field = temperature
    boundary = '8'
    value_type = max
  []
  [min_temp_side1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = min
  []
  [min_temp_side2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '2'
    value_type = min
  []
  [min_temp_side3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = min
  []
  [min_temp_side4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [min_temp_side5]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = min
  []
  [min_temp_side6]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = min
  []
  [min_temp_side7]
    type = NekSideExtremeValue
    field = temperature
    boundary = '7'
    value_type = min
  []
  [min_temp_side8]
    type = NekSideExtremeValue
    field = temperature
    boundary = '8'
    value_type = min
  []

  [max_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
  []
  [max_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
  []
  [max_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
  []
  [max_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
  []
  [max_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
  []
  [max_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
  []
  [max_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
  []
  [max_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
  []
  [min_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
    value_type = min
  []
  [min_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
    value_type = min
  []
  [min_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = min
  []
  [min_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
    value_type = min
  []
  [min_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
    value_type = min
  []
  [min_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
    value_type = min
  []
  [min_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
    value_type = min
  []
  [min_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
    value_type = min
  []

  [max_velocity_side1]
    type = NekSideExtremeValue
    field = velocity
    boundary = '1'
    value_type = max
  []
  [max_velocity_side2]
    type = NekSideExtremeValue
    field = velocity
    boundary = '2'
    value_type = max
  []
  [max_velocity_side3]
    type = NekSideExtremeValue
    field = velocity
    boundary = '3'
    value_type = max
  []
  [max_velocity_side4]
    type = NekSideExtremeValue
    field = velocity
    boundary = '4'
    value_type = max
  []
  [max_velocity_side5]
    type = NekSideExtremeValue
    field = velocity
    boundary = '5'
    value_type = max
  []
  [max_velocity_side6]
    type = NekSideExtremeValue
    field = velocity
    boundary = '6'
    value_type = max
  []
  [max_velocity_side7]
    type = NekSideExtremeValue
    field = velocity
    boundary = '7'
    value_type = max
  []
  [max_velocity_side8]
    type = NekSideExtremeValue
    field = velocity
    boundary = '8'
    value_type = max
  []
  [min_velocity_side1]
    type = NekSideExtremeValue
    field = velocity
    boundary = '1'
    value_type = min
  []
  [min_velocity_side2]
    type = NekSideExtremeValue
    field = velocity
    boundary = '2'
    value_type = min
  []
  [min_velocity_side3]
    type = NekSideExtremeValue
    field = velocity
    boundary = '3'
    value_type = min
  []
  [min_velocity_side4]
    type = NekSideExtremeValue
    field = velocity
    boundary = '4'
    value_type = min
  []
  [min_velocity_side5]
    type = NekSideExtremeValue
    field = velocity
    boundary = '5'
    value_type = min
  []
  [min_velocity_side6]
    type = NekSideExtremeValue
    field = velocity
    boundary = '6'
    value_type = min
  []
  [min_velocity_side7]
    type = NekSideExtremeValue
    field = velocity
    boundary = '7'
    value_type = min
  []
  [min_velocity_side8]
    type = NekSideExtremeValue
    field = velocity
    boundary = '8'
    value_type = min
  []

  [max_x_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '1'
    value_type = max
  []
  [max_x_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '2'
    value_type = max
  []
  [max_x_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '3'
    value_type = max
  []
  [max_x_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '4'
    value_type = max
  []
  [max_x_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '5'
    value_type = max
  []
  [max_x_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '6'
    value_type = max
  []
  [max_x_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '7'
    value_type = max
  []
  [max_x_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '8'
    value_type = max
  []
  [min_x_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '1'
    value_type = min
  []
  [min_x_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '2'
    value_type = min
  []
  [min_x_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '3'
    value_type = min
  []
  [min_x_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '4'
    value_type = min
  []
  [min_x_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '5'
    value_type = min
  []
  [min_x_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '6'
    value_type = min
  []
  [min_x_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '7'
    value_type = min
  []
  [min_x_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '8'
    value_type = min
  []
  [max_y_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '1'
    value_type = max
  []
  [max_y_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '2'
    value_type = max
  []
  [max_y_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '3'
    value_type = max
  []
  [max_y_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '4'
    value_type = max
  []
  [max_y_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '5'
    value_type = max
  []
  [max_y_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '6'
    value_type = max
  []
  [max_y_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '7'
    value_type = max
  []
  [max_y_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '8'
    value_type = max
  []
  [min_y_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '1'
    value_type = min
  []
  [min_y_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '2'
    value_type = min
  []
  [min_y_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '3'
    value_type = min
  []
  [min_y_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '4'
    value_type = min
  []
  [min_y_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '5'
    value_type = min
  []
  [min_y_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '6'
    value_type = min
  []
  [min_y_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '7'
    value_type = min
  []
  [min_y_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '8'
    value_type = min
  []
  [max_z_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '1'
    value_type = max
  []
  [max_z_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '2'
    value_type = max
  []
  [max_z_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '3'
    value_type = max
  []
  [max_z_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '4'
    value_type = max
  []
  [max_z_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '5'
    value_type = max
  []
  [max_z_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '6'
    value_type = max
  []
  [max_z_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '7'
    value_type = max
  []
  [max_z_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '8'
    value_type = max
  []
  [min_z_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '1'
    value_type = min
  []
  [min_z_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '2'
    value_type = min
  []
  [min_z_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '3'
    value_type = min
  []
  [min_z_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '4'
    value_type = min
  []
  [min_z_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '5'
    value_type = min
  []
  [min_z_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '6'
    value_type = min
  []
  [min_z_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '7'
    value_type = min
  []
  [min_z_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '8'
    value_type = min
  []
[]

(test/tests/nek_standalone/lowMach/nek.i)

[Mesh]
  type = NekRSMesh
  volume = true
  order = SECOND
[]

[Problem]
  type = NekRSStandaloneProblem
  casename = 'lowMach'
  output = 'pressure velocity temperature'

  # We omit the non-dimensional settings here in order to just extract the
  # non-dimensional solution as-is, without dimensionalizing it.
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  # All the following postprocessors are applying operations both (a) directly to the NekRS
  # solution arrays, and (b) to the variables extracted with the 'outputs = ...' syntax.
  # Rather than check the actual values of these postprocessors (which might change if the
  # NekRS development team changes the nature of their CI tests), we can just check that
  # the difference between the Nek-style postprocessors from the MOOSE-style postprocessors
  # (acting on the extract solution) are nearly zero. We only check the absolute value of
  # the min/max volume values for Vx, temperature, and pressure because those values are printed to
  # the screen and offer quick confirmation of any changes that are due to changes in NekRS itself.

  [max_Vx]
    type = NekVolumeExtremeValue
    field = velocity_x
    value_type = max
  []
  [max_Vx_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = max
  []
  [max_Vx_diff]
    type = DifferencePostprocessor
    value1 = max_Vx
    value2 = max_Vx_output
  []

  [min_Vx]
    type = NekVolumeExtremeValue
    field = velocity_x
    value_type = min
  []
  [min_Vx_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = min
  []
  [min_Vx_diff]
    type = DifferencePostprocessor
    value1 = min_Vx
    value2 = min_Vx_output
  []

  [max_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = max
  []
  [max_p_output]
    type = NodalExtremeValue
    variable = P
    value_type = max
  []
  [max_p_diff]
    type = DifferencePostprocessor
    value1 = max_p
    value2 = max_p_output
  []

  [min_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = min
  []
  [min_p_output]
    type = NodalExtremeValue
    variable = P
    value_type = min
  []
  [min_p_diff]
    type = DifferencePostprocessor
    value1 = min_p
    value2 = min_p_output
  []

  [max_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = max
  []
  [max_T_output]
    type = NodalExtremeValue
    variable = temp
    value_type = max
  []
  [max_T_diff]
    type = DifferencePostprocessor
    value1 = max_T
    value2 = max_T_output
  []

  [min_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = min
  []
  [min_T_output]
    type = NodalExtremeValue
    variable = temp
    value_type = min
  []
  [min_T_diff]
    type = DifferencePostprocessor
    value1 = min_T
    value2 = min_T_output
  []

  [area]
    type = NekSideIntegral
    field = unity
    boundary = '1'
  []
  [area_output]
    type = AreaPostprocessor
    boundary = '1'
  []
  [area_diff]
    type = DifferencePostprocessor
    value1 = area
    value2 = area_output
  []

  [volume]
    type = NekVolumeIntegral
    field = unity
  []
  [volume_output]
    type = VolumePostprocessor
  []
  [volume_diff]
    type = DifferencePostprocessor
    value1 = volume
    value2 = volume_output
  []

  [max_T_side]
    type = NekSideExtremeValue
    field = temperature
    value_type = max
    boundary = '1'
  []
  [max_T_side_output]
    type = NodalExtremeValue
    variable = temp
    value_type = max
    boundary = '1'
  []
  [max_T_side_diff]
    type = DifferencePostprocessor
    value1 = max_T_side
    value2 = max_T_side_output
  []

  [min_T_side]
    type = NekSideExtremeValue
    field = temperature
    value_type = min
    boundary = '1'
  []
  [min_T_side_output]
    type = NodalExtremeValue
    variable = temp
    value_type = min
    boundary = '1'
  []
  [min_T_side_diff]
    type = DifferencePostprocessor
    value1 = min_T_side
    value2 = min_T_side_output
  []

  [max_Vx_side]
    type = NekSideExtremeValue
    field = velocity_x
    value_type = max
    boundary = '1'
  []
  [max_Vx_side_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = max
    boundary = '1'
  []
  [max_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = max_Vx_side
    value2 = max_Vx_side_output
  []

  [min_Vx_side]
    type = NekSideExtremeValue
    field = velocity_x
    value_type = min
    boundary = '1'
  []
  [min_Vx_side_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = min
    boundary = '1'
  []
  [min_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = min_Vx_side
    value2 = min_Vx_side_output
  []

  [max_p_side]
    type = NekSideExtremeValue
    field = pressure
    value_type = max
    boundary = '1'
  []
  [max_p_side_output]
    type = NodalExtremeValue
    variable = P
    value_type = max
    boundary = '1'
  []
  [min_p_side_diff]
    type = DifferencePostprocessor
    value1 = min_p_side
    value2 = min_p_side_output
  []

  [min_p_side]
    type = NekSideExtremeValue
    field = pressure
    value_type = min
    boundary = '1'
  []
  [min_p_side_output]
    type = NodalExtremeValue
    variable = P
    value_type = min
    boundary = '1'
  []
  [max_p_side_diff]
    type = DifferencePostprocessor
    value1 = max_p_side
    value2 = max_p_side_output
  []

  [avg_T]
    type = NekVolumeAverage
    field = temperature
  []
  [avg_T_output]
    type = ElementAverageValue
    variable = temp
  []
  [avg_T_diff]
    type = DifferencePostprocessor
    value1 = avg_T
    value2 = avg_T_output
  []

  [avg_Vx]
    type = NekVolumeAverage
    field = velocity_x
  []
  [avg_Vx_output]
    type = ElementAverageValue
    variable = vel_x
  []
  [avg_Vx_diff]
    type = DifferencePostprocessor
    value1 = avg_Vx
    value2 = avg_Vx_output
  []

  [avg_T_side]
    type = NekSideAverage
    field = temperature
    boundary = '1'
  []
  [avg_T_side_output]
    type = SideAverageValue
    variable = temp
    boundary = '1'
  []
  [avg_T_side_diff]
    type = DifferencePostprocessor
    value1 = avg_T_side
    value2 = avg_T_side_output
  []

  [avg_Vx_side]
    type = NekSideAverage
    field = velocity_x
    boundary = '1'
  []
  [avg_Vx_side_output]
    type = SideAverageValue
    variable = vel_x
    boundary = '1'
  []
  [avg_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = avg_Vx_side
    value2 = avg_Vx_side_output
  []

  [avg_p_side]
    type = NekSideAverage
    field = pressure
    boundary = '1'
  []
  [avg_p_side_output]
    type = SideAverageValue
    variable = P
    boundary = '1'
  []
  [avg_p_side_diff]
    type = DifferencePostprocessor
    value1 = avg_p_side
    value2 = avg_p_side_output
  []
[]

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

  hide = 'max_Vx_output min_Vx_output max_p_output min_p_output area_output volume_output max_Vx_side max_Vx_side_output max_p_side max_p_side_output min_Vx_side min_Vx_side_output min_p_side min_p_side_output avg_Vx avg_Vx_output avg_Vx_side avg_Vx_side_output avg_p_side avg_p_side_output max_T_output min_T_output max_T_side max_T_side_output min_T_side min_T_side_output avg_T avg_T_output avg_T_side avg_T_side_output'
[]

(test/tests/cht/sfr_pincell/nek_vpp.i)

[Problem]
  type = NekRSProblem
  casename = 'sfr_pin'
  conserve_flux_by_sideset = true

  # we only technically need one scratch space slot for this problem,
  # so we can skip allocating extra
  n_usrwrk_slots = 1
[]

[Mesh]
  type = NekRSMesh
  boundary = '1'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [nek_flux]
    type = NekHeatFluxIntegral
    boundary = '1'
  []
  [average_inlet_T]
    type = NekSideAverage
    field = temperature
    boundary = '3'
    execute_on = initial
  []
  [average_outlet_T]
    type = NekSideAverage
    field = temperature
    boundary = '4'
  []
  [dT]
    type = DifferencePostprocessor
    value1 = average_outlet_T
    value2 = average_inlet_T
  []
  [inlet_mdot]
    type = NekMassFluxWeightedSideIntegral
    field = unity
    boundary = '3'
    execute_on = initial
  []

  # postprocessors for comparing against non-dimensional version in ../nondimensional
  # --> uncomment in order to get the reference values that the nondimensional boundary coupling
  #     was verified against
  #
  # # side integral
  # [area_1]
  #   type = NekSideIntegral
  #   field = unity
  #   boundary = '1'
  # []
  # [pressure_1]
  #   type = NekSideIntegral
  #   field = pressure
  #   boundary = '1'
  # []
  # [temperature_1]
  #   type = NekSideIntegral
  #   field = temperature
  #   boundary = '1'
  # []

  # # side average
  # [avg_area_1]
  #   type = NekSideAverage
  #   field = unity
  #   boundary = '1'
  # []
  # [avg_pressure_1]
  #   type = NekSideAverage
  #   field = pressure
  #   boundary = '1'
  # []
  # [avg_temperature_1]
  #   type = NekSideAverage
  #   field = temperature
  #   boundary = '1'
  # []

  # # volume integral
  # [volume]
  #   type = NekVolumeIntegral
  #   field = unity
  # []
  # [pressure_vol]
  #   type = NekVolumeIntegral
  #   field = pressure
  # []
  # [temperature_vol]
  #   type = NekVolumeIntegral
  #   field = temperature
  # []

  # # volume average
  # [avg_volume]
  #   type = NekVolumeAverage
  #   field = unity
  # []
  # [avg_pressure_vol]
  #   type = NekVolumeAverage
  #   field = pressure
  # []
  # [avg_temperature_vol]
  #   type = NekVolumeAverage
  #   field = temperature
  # []

  # # heat flux integral
  # [nek_flux]
  #   type = NekHeatFluxIntegral
  #   boundary = '1'
  # []

  # # mass flux weighted integral
  # [inlet_mdot]
  #   type = NekMassFluxWeightedSideIntegral
  #   field = unity
  #   boundary = '3'
  #   execute_on = initial
  # []
  # [outlet_T]
  #   type = NekMassFluxWeightedSideIntegral
  #   field = temperature
  #   boundary = '4'
  # []
  # [inlet_P]
  #   type = NekMassFluxWeightedSideIntegral
  #   field = pressure
  #   boundary = '4'
  # []

  # # mass flux weighted integral
  # [inlet_mdot_avg]
  #   type = NekMassFluxWeightedSideAverage
  #   field = unity
  #   boundary = '3'
  #   execute_on = initial
  # []
  # [outlet_T_avg]
  #   type = NekMassFluxWeightedSideAverage
  #   field = temperature
  #   boundary = '4'
  # []
  # [inlet_P_avg]
  #   type = NekMassFluxWeightedSideAverage
  #   field = pressure
  #   boundary = '4'
  # []

  # # extreme value postprocessors - VOLUME
  # [max_T]
  #   type = NekVolumeExtremeValue
  #   field = temperature
  #   value_type = max
  # []
  # [min_T]
  #   type = NekVolumeExtremeValue
  #   field = temperature
  #   value_type = min
  # []
  # [max_p]
  #   type = NekVolumeExtremeValue
  #   field = pressure
  #   value_type = max
  # []
  # [min_p]
  #   type = NekVolumeExtremeValue
  #   field = pressure
  #   value_type = min
  # []
  # [max_1]
  #   type = NekVolumeExtremeValue
  #   field = unity
  #   value_type = max
  # []
  # [min_1]
  #   type = NekVolumeExtremeValue
  #   field = unity
  #   value_type = min
  # []

  # # extreme value postprocessors - SIDE
  # [max_T_out]
  #   type = NekSideExtremeValue
  #   field = temperature
  #   boundary = '4'
  #   value_type = max
  # []
  # [min_T_out]
  #   type = NekSideExtremeValue
  #   field = temperature
  #   boundary = '4'
  #   value_type = min
  # []
  # [max_p_in]
  #   type = NekSideExtremeValue
  #   field = pressure
  #   boundary = '3'
  #   value_type = max
  # []
  # [min_p_in]
  #   type = NekSideExtremeValue
  #   field = pressure
  #   boundary = '3'
  #   value_type = min
  # []
  # [max_1_in]
  #   type = NekSideExtremeValue
  #   field = unity
  #   boundary = '3'
  #   value_type = max
  # []
  # [min_1_in]
  #   type = NekSideExtremeValue
  #   field = unity
  #   boundary = '3'
  #   value_type = min
  # []
[]

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

  [screen]
    type = Console
    hide = 'average_inlet_T average_outlet_T'
  []
[]

(test/tests/conduction/boundary_and_volume/prism/nek.i)

[Problem]
  type = NekRSProblem
  casename = 'pyramid'
[]

[Mesh]
  type = NekRSMesh
  volume = true
  boundary = '2'
  order = FIRST
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [max_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = max
  []
  [avg_T_volume]
    type = NekVolumeAverage
    field = temperature
  []
  [heat_flux]
    type = NekHeatFluxIntegral
    boundary = '2'
  []
  [nek_min_1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = min
  []
  [nek_min_2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [nek_min_3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = min
  []
  [nek_min_4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = min
  []
  [nek_max_1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
  []
  [nek_max_2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
  []
  [nek_max_3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
  []
  [nek_max_4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
  []
[]

[Outputs]
  exodus = true
  interval = 30

  hide = 'flux_integral source_integral'
[]

(test/tests/cht/nondimensional/nek_exact.i)

[Problem]
  type = NekRSProblem
  casename = 'sfr_pin'

  # This input is run in nondimensional form to verify that all the postprocessors
  # and data transfers in/out of nekRS are properly dimensionalized.
  nondimensional = true
  U_ref = 0.0950466
  T_ref = 628.15
  dT_ref = 50.0
  L_ref = 0.908e-2
  rho_0 = 834.5
  Cp_0 = 1228.0
[]

[Mesh]
  type = NekRSMesh
  boundary = '1'
  exact = true

  # nekRS runs in non-dimensional form, which means that we shrunk the mesh
  # from physical units of meters to our characteristic scale of 0.908e-2 m
  # (the pin pitch, arbitrarily chosen). That means that we must multiply
  # the nekRS mesh by 0.908e-2 to get back in units of meters that BISON is
  # running in.
  scaling = 0.908e-2
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
# pressure is not a reliable quantity to compare in a short, few-timestep regression test.
# This line can be uncommented for comparing with the dimensional version.
inactive = 'avg_pressure_1 avg_pressure_vol max_p max_p_in min_p_in pressure_1 pressure_vol'

  [synchronization_in]
    type = Receiver
  []

  # side integral
  [area_1]
    type = NekSideIntegral
    field = unity
    boundary = '1'
  []
  [pressure_1]
    type = NekSideIntegral
    field = pressure
    boundary = '1'
  []
  [temperature_1]
    type = NekSideIntegral
    field = temperature
    boundary = '1'
  []

  # side average
  [avg_area_1]
    type = NekSideAverage
    field = unity
    boundary = '1'
  []
  [avg_pressure_1]
    type = NekSideAverage
    field = pressure
    boundary = '1'
  []
  [avg_temperature_1]
    type = NekSideAverage
    field = temperature
    boundary = '1'
  []

  # volume integral
  [volume]
    type = NekVolumeIntegral
    field = unity
  []
  [pressure_vol]
    type = NekVolumeIntegral
    field = pressure
  []
  [temperature_vol]
    type = NekVolumeIntegral
    field = temperature
  []

  # volume average
  [avg_volume]
    type = NekVolumeAverage
    field = unity
  []
  [avg_pressure_vol]
    type = NekVolumeAverage
    field = pressure
  []
  [avg_temperature_vol]
    type = NekVolumeAverage
    field = temperature
  []

  # heat flux integral
  [nek_flux]
    type = NekHeatFluxIntegral
    boundary = '1'
  []

  # mass flux weighted integral
  [inlet_mdot]
    type = NekMassFluxWeightedSideIntegral
    field = unity
    boundary = '3'
    execute_on = initial
  []
  [outlet_T]
    type = NekMassFluxWeightedSideIntegral
    field = temperature
    boundary = '4'
  []
  [inlet_P]
    type = NekMassFluxWeightedSideIntegral
    field = pressure
    boundary = '4'
  []

  # mass flux weighted integral
  [inlet_mdot_avg]
    type = NekMassFluxWeightedSideAverage
    field = unity
    boundary = '3'
    execute_on = initial
  []
  [outlet_T_avg]
    type = NekMassFluxWeightedSideAverage
    field = temperature
    boundary = '4'
  []
  [inlet_P_avg]
    type = NekMassFluxWeightedSideAverage
    field = pressure
    boundary = '4'
  []

  # extreme value postprocessors - VOLUME
  [max_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = max
  []
  [min_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = min
  []
  [max_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = max
  []
  [min_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = min
  []
  [max_1]
    type = NekVolumeExtremeValue
    field = unity
    value_type = max
  []
  [min_1]
    type = NekVolumeExtremeValue
    field = unity
    value_type = min
  []

  # extreme value postprocessors - SIDE
  [max_T_out]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = max
  []
  [min_T_out]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [max_p_in]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = max
  []
  [min_p_in]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = min
  []
  [max_1_in]
    type = NekSideExtremeValue
    field = unity
    boundary = '3'
    value_type = max
  []
  [min_1_in]
    type = NekSideExtremeValue
    field = unity
    boundary = '3'
    value_type = min
  []
[]

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

  [screen]
    type = Console
    hide = 'synchronization_in'
  []
[]

(test/tests/nek_separatedomain/transfers_temperature/nek.i)

[Problem]
  type = NekRSSeparateDomainProblem

  inlet_boundary  = '1'
  outlet_boundary = '2'

  casename = 'pyramid'
[]

[Mesh]
  type = NekRSMesh
  boundary = '1'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [inlet_V_max]
    type = NekSideExtremeValue
    boundary = '1'
    field = velocity
    value_type = max
  []
  [inlet_V_min]
    type = NekSideExtremeValue
    boundary = '1'
    field = velocity
    value_type = min
  []
  [outlet_V_max]
    type = NekSideExtremeValue
    boundary = '2'
    field = velocity
    value_type = max
  []
  [outlet_V_min]
    type = NekSideExtremeValue
    boundary = '2'
    field = velocity
    value_type = min
  []
  [inlet_T_max]
    type = NekSideExtremeValue
    boundary = '1'
    field = temperature
    value_type = max
  []
  [inlet_T_min]
    type = NekSideExtremeValue
    boundary = '1'
    field = temperature
    value_type = min
  []
  [outlet_T_max]
    type = NekSideExtremeValue
    boundary = '2'
    field = temperature
    value_type = max
  []
  [outlet_T_min]
    type = NekSideExtremeValue
    boundary = '2'
    field = temperature
    value_type = min
  []
  [P_check]
    type = ParsedPostprocessor
    function = 'inlet_P - outlet_P - dP'
    pp_names = 'inlet_P outlet_P dP'
  []
[]


[MultiApps]
  [sub]
    type = FullSolveMultiApp
    input_files = 'cardinal_sub.i'
  []
[]

[Transfers]
  [toNekRS_velocity_trans]
    type = MultiAppPostprocessorTransfer
    from_multi_app = sub
    reduction_type = average
    from_postprocessor = toNekRS_velocity
    to_postprocessor   = inlet_V
  []
  [toNekRS_temperature_trans]
    type = MultiAppPostprocessorTransfer
    from_multi_app = sub
    reduction_type = average
    from_postprocessor = toNekRS_temperature
    to_postprocessor   = inlet_T
  []
[]

[Outputs]
  csv = true
[]

(test/tests/cht/nondimensional/nek.i)

[Problem]
  type = NekRSProblem
  casename = 'sfr_pin'

  # This input is run in nondimensional form to verify that all the postprocessors
  # and data transfers in/out of nekRS are properly dimensionalized.
  nondimensional = true
  U_ref = 0.0950466
  T_ref = 628.15
  dT_ref = 50.0
  L_ref = 0.908e-2
  rho_0 = 834.5
  Cp_0 = 1228.0
[]

[Mesh]
  type = NekRSMesh
  boundary = '1'

  # nekRS runs in non-dimensional form, which means that we shrunk the mesh
  # from physical units of meters to our characteristic scale of 0.908e-2 m
  # (the pin pitch, arbitrarily chosen). That means that we must multiply
  # the nekRS mesh by 0.908e-2 to get back in units of meters that BISON is
  # running in.
  scaling = 0.908e-2
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [synchronization_in]
    type = Receiver
  []

  # side integral
  [area_1]
    type = NekSideIntegral
    field = unity
    boundary = '1'
  []
  [pressure_1]
    type = NekSideIntegral
    field = pressure
    boundary = '1'
  []
  [temperature_1]
    type = NekSideIntegral
    field = temperature
    boundary = '1'
  []

  # side average
  [avg_area_1]
    type = NekSideAverage
    field = unity
    boundary = '1'
  []
  [avg_pressure_1]
    type = NekSideAverage
    field = pressure
    boundary = '1'
  []
  [avg_temperature_1]
    type = NekSideAverage
    field = temperature
    boundary = '1'
  []

  # volume integral
  [volume]
    type = NekVolumeIntegral
    field = unity
  []
  [pressure_vol]
    type = NekVolumeIntegral
    field = pressure
  []
  [temperature_vol]
    type = NekVolumeIntegral
    field = temperature
  []

  # volume average
  [avg_volume]
    type = NekVolumeAverage
    field = unity
  []
  [avg_pressure_vol]
    type = NekVolumeAverage
    field = pressure
  []
  [avg_temperature_vol]
    type = NekVolumeAverage
    field = temperature
  []

  # heat flux integral
  [nek_flux]
    type = NekHeatFluxIntegral
    boundary = '1'
  []

  # mass flux weighted integral
  [inlet_mdot]
    type = NekMassFluxWeightedSideIntegral
    field = unity
    boundary = '3'
    execute_on = initial
  []
  [outlet_T]
    type = NekMassFluxWeightedSideIntegral
    field = temperature
    boundary = '4'
  []
  [inlet_P]
    type = NekMassFluxWeightedSideIntegral
    field = pressure
    boundary = '4'
  []

  # mass flux weighted integral
  [inlet_mdot_avg]
    type = NekMassFluxWeightedSideAverage
    field = unity
    boundary = '3'
    execute_on = initial
  []
  [outlet_T_avg]
    type = NekMassFluxWeightedSideAverage
    field = temperature
    boundary = '4'
  []
  [inlet_P_avg]
    type = NekMassFluxWeightedSideAverage
    field = pressure
    boundary = '4'
  []

  # extreme value postprocessors - VOLUME
  [max_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = max
  []
  [min_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = min
  []
  [max_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = max
  []
  [min_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = min
  []
  [max_1]
    type = NekVolumeExtremeValue
    field = unity
    value_type = max
  []
  [min_1]
    type = NekVolumeExtremeValue
    field = unity
    value_type = min
  []

  # extreme value postprocessors - SIDE
  [max_T_out]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = max
  []
  [min_T_out]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [max_p_in]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = max
  []
  [min_p_in]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = min
  []
  [max_1_in]
    type = NekSideExtremeValue
    field = unity
    boundary = '3'
    value_type = max
  []
  [min_1_in]
    type = NekSideExtremeValue
    field = unity
    boundary = '3'
    value_type = min
  []
[]

[Outputs]
  exodus = true
  execute_on = 'final'

  [screen]
    type = Console
    hide = 'synchronization_in'
  []
[]

(test/tests/nek_stochastic/device/nek_multi.i)

[Mesh]
  type = NekRSMesh
  volume = true
[]

[Problem]
  type = NekRSStandaloneProblem
  casename = 'pyramid'
  n_usrwrk_slots = 1
  output = 'temperature'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[UserObjects]
  [scalar1]
    type = NekScalarValue
  []
[]

[Controls]
  [stochastic]
    type = SamplerReceiver
  []
[]

[Postprocessors]
  [s1]
    type = NekScalarValuePostprocessor
    userobject = scalar1
  []

  # we use the stochastic value to set the boundary condition on temperature on sideset 1;
  # we are checking that the value of the temperature on sideset 1 indeed matches that value
  [max_on_side]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = max
  []
  [min_on_side]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = min
  []
[]

[Outputs]
  csv = true
[]

(test/tests/postprocessors/nek_side_extrema/nek_p.i)

[Problem]
  type = NekRSProblem
[]

[Mesh]
  type = NekRSMesh
  boundary = '1 2 3 4 5 6 7 8'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Outputs]
  [out]
    type = CSV
    hide = 'flux_integral'
    execute_on = 'final'
  []
[]

[Postprocessors]
  [max_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
    value_type = max
  []
  [max_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
    value_type = max
  []
  [max_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = max
  []
  [max_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
    value_type = max
  []
  [max_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
    value_type = max
  []
  [max_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
    value_type = max
  []
  [max_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
    value_type = max
  []
  [max_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
    value_type = max
  []
  [min_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
    value_type = min
  []
  [min_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
    value_type = min
  []
  [min_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = min
  []
  [min_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
    value_type = min
  []
  [min_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
    value_type = min
  []
  [min_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
    value_type = min
  []
  [min_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
    value_type = min
  []
  [min_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
    value_type = min
  []
[]

(test/tests/conduction/boundary_and_volume/prism/nek_exact.i)

[Problem]
  type = NekRSProblem
  casename = 'pyramid_low'
  usrwrk_output = '0 1'
  usrwrk_output_prefix = 'flx src'
[]

[Mesh]
  type = NekRSMesh
  volume = true
  boundary = '2'
  order = FIRST
  exact = true
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [max_T]
    type = NekVolumeExtremeValue
    field = temperature
    value_type = max
  []
  [avg_T_volume]
    type = NekVolumeAverage
    field = temperature
  []
  [heat_flux]
    type = NekHeatFluxIntegral
    boundary = '2'
  []
  [nek_min_1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = min
  []
  [nek_min_2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [nek_min_3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = min
  []
  [nek_min_4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = min
  []
  [nek_max_1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
  []
  [nek_max_2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
  []
  [nek_max_3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
  []
  [nek_max_4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
  []
[]

[Outputs]
  exodus = true
  interval = 30

  hide = 'flux_integral source_integral'
[]

(test/tests/nek_standalone/lowMach/nek_boundary.i)

[Mesh]
  type = NekRSMesh
  boundary = '1'
  order = SECOND
[]

[Problem]
  type = NekRSStandaloneProblem
  casename = 'lowMach'
  output = 'pressure velocity temperature'

  # We omit the non-dimensional settings here in order to just extract the
  # non-dimensional solution as-is, without dimensionalizing it.
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [max_T_side]
    type = NekSideExtremeValue
    field = temperature
    value_type = max
    boundary = '1'
  []
  [max_T_side_output]
    type = NodalExtremeValue
    variable = temp
    value_type = max
  []
  [max_T_side_diff]
    type = DifferencePostprocessor
    value1 = max_T_side
    value2 = max_T_side_output
  []

  [min_T_side]
    type = NekSideExtremeValue
    field = temperature
    value_type = min
    boundary = '1'
  []
  [min_T_side_output]
    type = NodalExtremeValue
    variable = temp
    value_type = min
  []
  [min_T_side_diff]
    type = DifferencePostprocessor
    value1 = min_T_side
    value2 = min_T_side_output
  []

  [max_Vx_side]
    type = NekSideExtremeValue
    field = velocity_x
    value_type = max
    boundary = '1'
  []
  [max_Vx_side_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = max
  []
  [max_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = max_Vx_side
    value2 = max_Vx_side_output
  []

  [min_Vx_side]
    type = NekSideExtremeValue
    field = velocity_x
    value_type = min
    boundary = '1'
  []
  [min_Vx_side_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = min
  []
  [min_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = min_Vx_side
    value2 = min_Vx_side_output
  []

  [max_p_side]
    type = NekSideExtremeValue
    field = pressure
    value_type = max
    boundary = '1'
  []
  [max_p_side_output]
    type = NodalExtremeValue
    variable = P
    value_type = max
  []
  [min_p_side_diff]
    type = DifferencePostprocessor
    value1 = min_p_side
    value2 = min_p_side_output
  []

  [min_p_side]
    type = NekSideExtremeValue
    field = pressure
    value_type = min
    boundary = '1'
  []
  [min_p_side_output]
    type = NodalExtremeValue
    variable = P
    value_type = min
  []
  [max_p_side_diff]
    type = DifferencePostprocessor
    value1 = max_p_side
    value2 = max_p_side_output
  []

  [avg_T_side]
    type = NekSideAverage
    field = temperature
    boundary = '1'
  []
  [avg_T_side_output]
    type = ElementAverageValue
    variable = temp
  []
  [avg_T_side_diff]
    type = DifferencePostprocessor
    value1 = avg_T_side
    value2 = avg_T_side_output
  []

  [avg_Vx_side]
    type = NekSideAverage
    field = velocity_x
    boundary = '1'
  []
  [avg_Vx_side_output]
    type = ElementAverageValue
    variable = vel_x
  []
  [avg_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = avg_Vx_side
    value2 = avg_Vx_side_output
  []

  [avg_p_side]
    type = NekSideAverage
    field = pressure
    boundary = '1'
  []
  [avg_p_side_output]
    type = ElementAverageValue
    variable = P
  []
  [avg_p_side_diff]
    type = DifferencePostprocessor
    value1 = avg_p_side
    value2 = avg_p_side_output
  []
[]

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

  hide = 'max_Vx_side max_Vx_side_output max_p_side max_p_side_output min_Vx_side min_Vx_side_output min_p_side min_p_side_output avg_Vx_side avg_Vx_side_output avg_p_side avg_p_side_output max_T_side max_T_side_output min_T_side min_T_side_output avg_T_side avg_T_side_output'
[]

(test/tests/nek_standalone/channel/nek.i)

[Mesh]
  type = NekRSMesh
  volume = true
[]

[Problem]
  type = NekRSStandaloneProblem
  casename = 'channel'
  output = 'pressure velocity'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [max_Vx]
    type = NekVolumeExtremeValue
    field = velocity_x
    value_type = max
  []
  [max_Vx_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = max
  []
  [max_Vx_diff]
    type = DifferencePostprocessor
    value1 = max_Vx
    value2 = max_Vx_output
  []

  [min_Vx]
    type = NekVolumeExtremeValue
    field = velocity_x
    value_type = min
  []
  [min_Vx_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = min
  []
  [min_Vx_diff]
    type = DifferencePostprocessor
    value1 = min_Vx
    value2 = min_Vx_output
  []

  [max_Vy]
    type = NekVolumeExtremeValue
    field = velocity_y
    value_type = max
  []
  [max_Vy_output]
    type = NodalExtremeValue
    variable = vel_y
    value_type = max
  []
  [max_Vy_diff]
    type = DifferencePostprocessor
    value1 = max_Vy
    value2 = max_Vy_output
  []

  [min_Vy]
    type = NekVolumeExtremeValue
    field = velocity_y
    value_type = min
  []
  [min_Vy_output]
    type = NodalExtremeValue
    variable = vel_y
    value_type = min
  []

  [max_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = max
  []
  [max_p_output]
    type = NodalExtremeValue
    variable = P
    value_type = max
  []
  [max_p_diff]
    type = DifferencePostprocessor
    value1 = max_p
    value2 = max_p_output
  []

  [min_p]
    type = NekVolumeExtremeValue
    field = pressure
    value_type = min
  []
  [min_p_output]
    type = NodalExtremeValue
    variable = P
    value_type = min
  []
  [min_p_diff]
    type = DifferencePostprocessor
    value1 = min_p
    value2 = min_p_output
  []

  [area]
    type = NekSideIntegral
    field = unity
    boundary = '1'
  []
  [area_output]
    type = AreaPostprocessor
    boundary = '1'
  []
  [area_diff]
    type = DifferencePostprocessor
    value1 = area
    value2 = area_output
  []

  [volume]
    type = NekVolumeIntegral
    field = unity
  []
  [volume_output]
    type = VolumePostprocessor
  []
  [volume_diff]
    type = DifferencePostprocessor
    value1 = volume
    value2 = volume_output
  []

  [max_Vx_side]
    type = NekSideExtremeValue
    field = velocity_x
    value_type = max
    boundary = '1'
  []
  [max_Vx_side_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = max
    boundary = '1'
  []
  [max_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = max_Vx_side
    value2 = max_Vx_side_output
  []

  [max_Vy_side]
    type = NekSideExtremeValue
    field = velocity_y
    value_type = max
    boundary = '1'
  []
  [max_Vy_side_output]
    type = NodalExtremeValue
    variable = vel_y
    value_type = max
    boundary = '1'
  []
  [max_Vy_side_diff]
    type = DifferencePostprocessor
    value1 = max_Vy_side
    value2 = max_Vy_side_output
  []

  [min_Vx_side]
    type = NekSideExtremeValue
    field = velocity_x
    value_type = min
    boundary = '1'
  []
  [min_Vx_side_output]
    type = NodalExtremeValue
    variable = vel_x
    value_type = min
    boundary = '1'
  []
  [min_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = min_Vx_side
    value2 = min_Vx_side_output
  []

  [min_Vy_side]
    type = NekSideExtremeValue
    field = velocity_y
    value_type = min
    boundary = '1'
  []
  [min_Vy_side_output]
    type = NodalExtremeValue
    variable = vel_y
    value_type = min
    boundary = '1'
  []
  [min_Vy_side_diff]
    type = DifferencePostprocessor
    value1 = min_Vy_side
    value2 = min_Vy_side_output
  []

  [max_p_side]
    type = NekSideExtremeValue
    field = pressure
    value_type = max
    boundary = '1'
  []
  [max_p_side_output]
    type = NodalExtremeValue
    variable = P
    value_type = max
    boundary = '1'
  []
  [min_p_side_diff]
    type = DifferencePostprocessor
    value1 = min_p_side
    value2 = min_p_side_output
  []

  [min_p_side]
    type = NekSideExtremeValue
    field = pressure
    value_type = min
    boundary = '1'
  []
  [min_p_side_output]
    type = NodalExtremeValue
    variable = P
    value_type = min
    boundary = '1'
  []
  [max_p_side_diff]
    type = DifferencePostprocessor
    value1 = max_p_side
    value2 = max_p_side_output
  []

  [avg_p]
    type = NekVolumeAverage
    field = pressure
  []
  [avg_p_output]
    type = ElementAverageValue
    variable = P
  []
  [avg_p_diff]
    type = DifferencePostprocessor
    value1 = avg_p
    value2 = avg_p_output
  []

  [avg_Vx]
    type = NekVolumeAverage
    field = velocity_x
  []
  [avg_Vx_output]
    type = ElementAverageValue
    variable = vel_x
  []
  [avg_Vx_diff]
    type = DifferencePostprocessor
    value1 = avg_Vx
    value2 = avg_Vx_output
  []

  [avg_Vy]
    type = NekVolumeAverage
    field = velocity_y
  []
  [avg_Vy_output]
    type = ElementAverageValue
    variable = vel_y
  []
  [avg_Vy_diff]
    type = DifferencePostprocessor
    value1 = avg_Vy
    value2 = avg_Vy_output
  []

  [avg_Vx_side]
    type = NekSideAverage
    field = velocity_x
    boundary = '1'
  []
  [avg_Vx_side_output]
    type = SideAverageValue
    variable = vel_x
    boundary = '1'
  []
  [avg_Vx_side_diff]
    type = DifferencePostprocessor
    value1 = avg_Vx_side
    value2 = avg_Vx_side_output
  []

  [avg_Vy_side]
    type = NekSideAverage
    field = velocity_y
    boundary = '1'
  []
  [avg_Vy_side_output]
    type = SideAverageValue
    variable = vel_y
    boundary = '1'
  []
  [avg_Vy_side_diff]
    type = DifferencePostprocessor
    value1 = avg_Vy_side
    value2 = avg_Vy_side_output
  []

  [avg_p_side]
    type = NekSideAverage
    field = pressure
    boundary = '1'
  []
  [avg_p_side_output]
    type = SideAverageValue
    variable = P
    boundary = '1'
  []
  [avg_p_side_diff]
    type = DifferencePostprocessor
    value1 = avg_p_side
    value2 = avg_p_side_output
  []
[]

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

  hide = 'max_Vx_output min_Vx_output max_Vy_output min_Vy_output max_p_output min_p_output area_output volume_output max_Vx_side max_Vx_side_output max_Vy_side max_Vy_side_output max_p_side max_p_side_output min_Vx_side min_Vx_side_output min_Vy_side min_Vy_side_output min_p_side min_p_side_output avg_p avg_p_output avg_Vx avg_Vx_output avg_Vy avg_Vy_output avg_Vx_side avg_Vx_side_output avg_Vy_side avg_Vy_side_output avg_p_side avg_p_side_output max_Vx max_Vy max_p min_Vx min_Vy min_p area'
[]

(test/tests/postprocessors/nek_side_extrema/nek.i)

[Problem]
  type = NekRSProblem
  casename = 'pyramid'
[]

[Mesh]
  type = NekRSMesh
  boundary = '1 2 3 4 5 6 7 8'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Outputs]
  [out]
    type = CSV
    hide = 'flux_integral'
    execute_on = 'final'
  []
[]

[Postprocessors]
  [max_temp_side1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = max
  []
  [max_temp_side2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '2'
    value_type = max
  []
  [max_temp_side3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = max
  []
  [max_temp_side4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = max
  []
  [max_temp_side5]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = max
  []
  [max_temp_side6]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = max
  []
  [max_temp_side7]
    type = NekSideExtremeValue
    field = temperature
    boundary = '7'
    value_type = max
  []
  [max_temp_side8]
    type = NekSideExtremeValue
    field = temperature
    boundary = '8'
    value_type = max
  []
  [min_temp_side1]
    type = NekSideExtremeValue
    field = temperature
    boundary = '1'
    value_type = min
  []
  [min_temp_side2]
    type = NekSideExtremeValue
    field = temperature
    boundary = '2'
    value_type = min
  []
  [min_temp_side3]
    type = NekSideExtremeValue
    field = temperature
    boundary = '3'
    value_type = min
  []
  [min_temp_side4]
    type = NekSideExtremeValue
    field = temperature
    boundary = '4'
    value_type = min
  []
  [min_temp_side5]
    type = NekSideExtremeValue
    field = temperature
    boundary = '5'
    value_type = min
  []
  [min_temp_side6]
    type = NekSideExtremeValue
    field = temperature
    boundary = '6'
    value_type = min
  []
  [min_temp_side7]
    type = NekSideExtremeValue
    field = temperature
    boundary = '7'
    value_type = min
  []
  [min_temp_side8]
    type = NekSideExtremeValue
    field = temperature
    boundary = '8'
    value_type = min
  []

  [max_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
  []
  [max_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
  []
  [max_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
  []
  [max_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
  []
  [max_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
  []
  [max_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
  []
  [max_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
  []
  [max_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
  []
  [min_pressure_side1]
    type = NekSideExtremeValue
    field = pressure
    boundary = '1'
    value_type = min
  []
  [min_pressure_side2]
    type = NekSideExtremeValue
    field = pressure
    boundary = '2'
    value_type = min
  []
  [min_pressure_side3]
    type = NekSideExtremeValue
    field = pressure
    boundary = '3'
    value_type = min
  []
  [min_pressure_side4]
    type = NekSideExtremeValue
    field = pressure
    boundary = '4'
    value_type = min
  []
  [min_pressure_side5]
    type = NekSideExtremeValue
    field = pressure
    boundary = '5'
    value_type = min
  []
  [min_pressure_side6]
    type = NekSideExtremeValue
    field = pressure
    boundary = '6'
    value_type = min
  []
  [min_pressure_side7]
    type = NekSideExtremeValue
    field = pressure
    boundary = '7'
    value_type = min
  []
  [min_pressure_side8]
    type = NekSideExtremeValue
    field = pressure
    boundary = '8'
    value_type = min
  []

  [max_velocity_side1]
    type = NekSideExtremeValue
    field = velocity
    boundary = '1'
    value_type = max
  []
  [max_velocity_side2]
    type = NekSideExtremeValue
    field = velocity
    boundary = '2'
    value_type = max
  []
  [max_velocity_side3]
    type = NekSideExtremeValue
    field = velocity
    boundary = '3'
    value_type = max
  []
  [max_velocity_side4]
    type = NekSideExtremeValue
    field = velocity
    boundary = '4'
    value_type = max
  []
  [max_velocity_side5]
    type = NekSideExtremeValue
    field = velocity
    boundary = '5'
    value_type = max
  []
  [max_velocity_side6]
    type = NekSideExtremeValue
    field = velocity
    boundary = '6'
    value_type = max
  []
  [max_velocity_side7]
    type = NekSideExtremeValue
    field = velocity
    boundary = '7'
    value_type = max
  []
  [max_velocity_side8]
    type = NekSideExtremeValue
    field = velocity
    boundary = '8'
    value_type = max
  []
  [min_velocity_side1]
    type = NekSideExtremeValue
    field = velocity
    boundary = '1'
    value_type = min
  []
  [min_velocity_side2]
    type = NekSideExtremeValue
    field = velocity
    boundary = '2'
    value_type = min
  []
  [min_velocity_side3]
    type = NekSideExtremeValue
    field = velocity
    boundary = '3'
    value_type = min
  []
  [min_velocity_side4]
    type = NekSideExtremeValue
    field = velocity
    boundary = '4'
    value_type = min
  []
  [min_velocity_side5]
    type = NekSideExtremeValue
    field = velocity
    boundary = '5'
    value_type = min
  []
  [min_velocity_side6]
    type = NekSideExtremeValue
    field = velocity
    boundary = '6'
    value_type = min
  []
  [min_velocity_side7]
    type = NekSideExtremeValue
    field = velocity
    boundary = '7'
    value_type = min
  []
  [min_velocity_side8]
    type = NekSideExtremeValue
    field = velocity
    boundary = '8'
    value_type = min
  []

  [max_x_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '1'
    value_type = max
  []
  [max_x_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '2'
    value_type = max
  []
  [max_x_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '3'
    value_type = max
  []
  [max_x_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '4'
    value_type = max
  []
  [max_x_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '5'
    value_type = max
  []
  [max_x_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '6'
    value_type = max
  []
  [max_x_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '7'
    value_type = max
  []
  [max_x_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '8'
    value_type = max
  []
  [min_x_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '1'
    value_type = min
  []
  [min_x_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '2'
    value_type = min
  []
  [min_x_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '3'
    value_type = min
  []
  [min_x_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '4'
    value_type = min
  []
  [min_x_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '5'
    value_type = min
  []
  [min_x_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '6'
    value_type = min
  []
  [min_x_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '7'
    value_type = min
  []
  [min_x_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_x
    boundary = '8'
    value_type = min
  []
  [max_y_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '1'
    value_type = max
  []
  [max_y_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '2'
    value_type = max
  []
  [max_y_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '3'
    value_type = max
  []
  [max_y_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '4'
    value_type = max
  []
  [max_y_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '5'
    value_type = max
  []
  [max_y_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '6'
    value_type = max
  []
  [max_y_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '7'
    value_type = max
  []
  [max_y_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '8'
    value_type = max
  []
  [min_y_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '1'
    value_type = min
  []
  [min_y_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '2'
    value_type = min
  []
  [min_y_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '3'
    value_type = min
  []
  [min_y_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '4'
    value_type = min
  []
  [min_y_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '5'
    value_type = min
  []
  [min_y_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '6'
    value_type = min
  []
  [min_y_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '7'
    value_type = min
  []
  [min_y_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_y
    boundary = '8'
    value_type = min
  []
  [max_z_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '1'
    value_type = max
  []
  [max_z_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '2'
    value_type = max
  []
  [max_z_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '3'
    value_type = max
  []
  [max_z_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '4'
    value_type = max
  []
  [max_z_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '5'
    value_type = max
  []
  [max_z_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '6'
    value_type = max
  []
  [max_z_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '7'
    value_type = max
  []
  [max_z_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '8'
    value_type = max
  []
  [min_z_velocity_side1]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '1'
    value_type = min
  []
  [min_z_velocity_side2]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '2'
    value_type = min
  []
  [min_z_velocity_side3]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '3'
    value_type = min
  []
  [min_z_velocity_side4]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '4'
    value_type = min
  []
  [min_z_velocity_side5]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '5'
    value_type = min
  []
  [min_z_velocity_side6]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '6'
    value_type = min
  []
  [min_z_velocity_side7]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '7'
    value_type = min
  []
  [min_z_velocity_side8]
    type = NekSideExtremeValue
    field = velocity_z
    boundary = '8'
    value_type = min
  []
[]

(test/tests/cht/sfr_pincell/nek.i)

[Problem]
  type = NekRSProblem
  casename = 'sfr_pin'
  synchronization_interval = parent_app

  # we only technically need one scratch space slot for this problem,
  # so we can skip allocating extra
  n_usrwrk_slots = 1
[]

[Mesh]
  type = NekRSMesh
  boundary = '1'
[]

[Executioner]
  type = Transient

  [TimeStepper]
    type = NekTimeStepper
  []
[]

[Postprocessors]
  [nek_flux]
    type = NekHeatFluxIntegral
    boundary = '1'
  []
  [average_inlet_T]
    type = NekSideAverage
    field = temperature
    boundary = '3'
    execute_on = initial
  []
  [average_outlet_T]
    type = NekSideAverage
    field = temperature
    boundary = '4'
  []
  [dT]
    type = DifferencePostprocessor
    value1 = average_outlet_T
    value2 = average_inlet_T
  []
  [inlet_mdot]
    type = NekMassFluxWeightedSideIntegral
    field = unity
    boundary = '3'
    execute_on = initial
  []

  # postprocessors for comparing against non-dimensional version in ../nondimensional
  # --> uncomment in order to get the reference values that the nondimensional boundary coupling
  #     was verified against
  #
  # # side integral
  # [area_1]
  #   type = NekSideIntegral
  #   field = unity
  #   boundary = '1'
  # []
  # [pressure_1]
  #   type = NekSideIntegral
  #   field = pressure
  #   boundary = '1'
  # []
  # [temperature_1]
  #   type = NekSideIntegral
  #   field = temperature
  #   boundary = '1'
  # []

  # # side average
  # [avg_area_1]
  #   type = NekSideAverage
  #   field = unity
  #   boundary = '1'
  # []
  # [avg_pressure_1]
  #   type = NekSideAverage
  #   field = pressure
  #   boundary = '1'
  # []
  # [avg_temperature_1]
  #   type = NekSideAverage
  #   field = temperature
  #   boundary = '1'
  # []

  # # volume integral
  # [volume]
  #   type = NekVolumeIntegral
  #   field = unity
  # []
  # [pressure_vol]
  #   type = NekVolumeIntegral
  #   field = pressure
  # []
  # [temperature_vol]
  #   type = NekVolumeIntegral
  #   field = temperature
  # []

  # # volume average
  # [avg_volume]
  #   type = NekVolumeAverage
  #   field = unity
  # []
  # [avg_pressure_vol]
  #   type = NekVolumeAverage
  #   field = pressure
  # []
  # [avg_temperature_vol]
  #   type = NekVolumeAverage
  #   field = temperature
  # []

  # # heat flux integral
  # [nek_flux]
  #   type = NekHeatFluxIntegral
  #   boundary = '1'
  # []

  # # mass flux weighted integral
  # [inlet_mdot]
  #   type = NekMassFluxWeightedSideIntegral
  #   field = unity
  #   boundary = '3'
  #   execute_on = initial
  # []
  # [outlet_T]
  #   type = NekMassFluxWeightedSideIntegral
  #   field = temperature
  #   boundary = '4'
  # []
  # [inlet_P]
  #   type = NekMassFluxWeightedSideIntegral
  #   field = pressure
  #   boundary = '4'
  # []

  # # mass flux weighted integral
  # [inlet_mdot_avg]
  #   type = NekMassFluxWeightedSideAverage
  #   field = unity
  #   boundary = '3'
  #   execute_on = initial
  # []
  # [outlet_T_avg]
  #   type = NekMassFluxWeightedSideAverage
  #   field = temperature
  #   boundary = '4'
  # []
  # [inlet_P_avg]
  #   type = NekMassFluxWeightedSideAverage
  #   field = pressure
  #   boundary = '4'
  # []

  # # extreme value postprocessors - VOLUME
  # [max_T]
  #   type = NekVolumeExtremeValue
  #   field = temperature
  #   value_type = max
  # []
  # [min_T]
  #   type = NekVolumeExtremeValue
  #   field = temperature
  #   value_type = min
  # []
  # [max_p]
  #   type = NekVolumeExtremeValue
  #   field = pressure
  #   value_type = max
  # []
  # [min_p]
  #   type = NekVolumeExtremeValue
  #   field = pressure
  #   value_type = min
  # []
  # [max_1]
  #   type = NekVolumeExtremeValue
  #   field = unity
  #   value_type = max
  # []
  # [min_1]
  #   type = NekVolumeExtremeValue
  #   field = unity
  #   value_type = min
  # []

  # # extreme value postprocessors - SIDE
  # [max_T_out]
  #   type = NekSideExtremeValue
  #   field = temperature
  #   boundary = '4'
  #   value_type = max
  # []
  # [min_T_out]
  #   type = NekSideExtremeValue
  #   field = temperature
  #   boundary = '4'
  #   value_type = min
  # []
  # [max_p_in]
  #   type = NekSideExtremeValue
  #   field = pressure
  #   boundary = '3'
  #   value_type = max
  # []
  # [min_p_in]
  #   type = NekSideExtremeValue
  #   field = pressure
  #   boundary = '3'
  #   value_type = min
  # []
  # [max_1_in]
  #   type = NekSideExtremeValue
  #   field = unity
  #   boundary = '3'
  #   value_type = max
  # []
  # [min_1_in]
  #   type = NekSideExtremeValue
  #   field = unity
  #   boundary = '3'
  #   value_type = min
  # []
[]

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

  [screen]
    type = Console
    hide = 'average_inlet_T average_outlet_T transfer_in'
  []
[]

Description
Example Input Syntax
Input Parameters
Input Files