GapFluxModelRadiation

Gap flux model for heat conduction across a gap due to radiation, based on the diffusion approximation. Uses a coupled temperature variable.

Description

GapFluxModelRadiation computes a radiative heat flux across a gap following the diffusion approximation of radiation physics. This user object must be used in combination with ModularGapConductanceConstraint.

The heat flux across the gap is given by the classical expression (1) where is the Stephan-Boltzmann constant, is an emissivity function, is the surface temperature, is the farfield temperature, and is the radiant gap conductance. This expression can be rearranged to solve for : which reduces to (2)

If the coordinate system type is Cartesian, the emissivity is computed using an infinite parallel plate approximation given by (3) where and are the near surface and farfield emissivity values, respectively. The primary and secondary surface emissivity values can be assigned arbitrarily to and . For an axisymmetric coordinate system, the emissivity is computed using the same formula as that given in FVInfiniteCylinderRadiativeBC:

Here the subscript should correspond to whichever surface (secondary or primary) has the smaller radius, and the subscript should correspond to whichever surface has the larger radius.

Example Input File Syntax

[radiation]
  type = GapFluxModelRadiation
  temperature = temp
  boundary = 100
  primary_emissivity = 1.0
  secondary_emissivity = 1.0
  use_displaced_mesh = true
[]
(moose/modules/heat_conduction/test/tests/gap_heat_transfer_mortar/modular_gap_heat_transfer_mortar_displaced_radiation.i)

GapFluxModelRadiation must be used in conjunction with the modular gap conductance constraint as shown below:

[ced]
  type = ModularGapConductanceConstraint
  variable = lm
  secondary_variable = temp
  use_displaced_mesh = true
  primary_boundary = 100
  primary_subdomain = 10000
  secondary_boundary = 101
  secondary_subdomain = 10001
  gap_flux_models = radiation
[]
(moose/modules/heat_conduction/test/tests/gap_heat_transfer_mortar/modular_gap_heat_transfer_mortar_displaced_radiation.i)

Input Parameters

  • boundaryThe list of boundary IDs from the mesh where this object applies

    C++ Type:std::vector<BoundaryName>

    Controllable:No

    Description:The list of boundary IDs from the mesh where this object applies

  • temperatureThe name of the temperature variable

    C++ Type:std::vector<VariableName>

    Controllable:No

    Description:The name of the temperature variable

Required Parameters

  • primary_emissivity1The emissivity of the primary surface

    Default:1

    C++ Type:double

    Controllable:No

    Description:The emissivity of the primary surface

  • 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.

  • secondary_emissivity1The emissivity of the secondary surface

    Default:1

    C++ Type:double

    Controllable:No

    Description:The emissivity of the secondary surface

  • stefan_boltzmann5.67037e-08Stefan-Boltzmann constant

    Default:5.67037e-08

    C++ Type:double

    Controllable:No

    Description:Stefan-Boltzmann constant

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

  • implicitTrueDetermines whether this object is calculated using an implicit or explicit form

    Default:True

    C++ Type:bool

    Controllable:No

    Description:Determines whether this object is calculated using an implicit or explicit form

  • use_displaced_meshTrueWhether 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:True

    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

References

No citations exist within this document.