- variableThe name of the variable that this boundary condition applies to
C++ Type:NonlinearVariableName

Description:The name of the variable that this boundary condition applies to

- boundaryThe list of boundary IDs from the mesh where this boundary condition applies
C++ Type:std::vector

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

# GapHeatTransfer

Transfers heat across a gap between two surfaces dependant on the gap geometry specified.

## Description

GapHeatTransfer calculates the amount of heat transferred across unmeshed gaps between two different blocks.

The `quadrature`

option is generally recommended for most models. With this option, heat flux is computed and applied as an integrated boundary condition at the quadrature points on both faces. Use of the quadrature options generally gives smoother results, although there can be small differences in the heat flux on the two surfaces.

It is also important to use the appropriate `gap_geometry_type`

parameter (PLATE, CYLINDER, or SPHERE) for the model geometry.

## Example Input syntax

```
[ThermalContact]
[./left_to_right]
slave = leftright
quadrature = true
master = rightleft
variable = temp
type = GapHeatTransfer
[../]
[]
```

(modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/nonmatching.i)## Input Parameters

- gap_tempTemperature on the other side of the gap
C++ Type:std::vector

Description:Temperature on the other side of the gap

- gap_geometry_typeGap calculation type. Choices are: PLATE CYLINDER SPHERE
C++ Type:MooseEnum

Description:Gap calculation type. Choices are: PLATE CYLINDER SPHERE

- disp_zThe z displacement
C++ Type:std::vector

Description:The z displacement

- disp_yThe y displacement
C++ Type:std::vector

Description:The y displacement

- disp_xThe x displacement
C++ Type:std::vector

Description:The x displacement

- paired_boundaryThe boundary to be penetrated
C++ Type:BoundaryName

Description:The boundary to be penetrated

- warningsFalseWhether to output warning messages concerning nodes not being found
Default:False

C++ Type:bool

Description:Whether to output warning messages concerning nodes not being found

- appended_property_nameName appended to material properties to make them unique
C++ Type:std::string

Description:Name appended to material properties to make them unique

- max_gap1e+06A maximum gap size
Default:1e+06

C++ Type:double

Description:A maximum gap size

- quadratureFalseWhether or not to do Quadrature point based gap heat transfer. If this is true then gap_distance and gap_temp should NOT be provided (and will be ignored) however paired_boundary IS then required.
Default:False

C++ Type:bool

Description:Whether or not to do Quadrature point based gap heat transfer. If this is true then gap_distance and gap_temp should NOT be provided (and will be ignored) however paired_boundary IS then required.

- min_gap1e-06A minimum gap size
Default:1e-06

C++ Type:double

Description:A minimum gap size

- sphere_originOrigin for sphere geometry
C++ Type:libMesh::VectorValue

Description:Origin for sphere geometry

- gap_distanceDistance across the gap
C++ Type:std::vector

Description:Distance across the gap

- cylinder_axis_point_1Start point for line defining cylindrical axis
C++ Type:libMesh::VectorValue

Description:Start point for line defining cylindrical axis

- cylinder_axis_point_2End point for line defining cylindrical axis
C++ Type:libMesh::VectorValue

Description:End point for line defining cylindrical axis

- orderFIRSTThe finite element order
Default:FIRST

C++ Type:MooseEnum

Description:The finite element order

- displacementsThe displacements appropriate for the simulation geometry and coordinate system
C++ Type:std::vector

Description:The displacements appropriate for the simulation geometry and coordinate system

### Optional Parameters

- enableTrueSet the enabled status of the MooseObject.
Default:True

C++ Type:bool

Description:Set the enabled status of the MooseObject.

- save_inThe name of auxiliary variables to save this BC's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)
C++ Type:std::vector

Description:The name of auxiliary variables to save this BC's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

- use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False

C++ Type:bool

Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

- control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector

Description:Adds user-defined labels for accessing object parameters via control logic.

- seed0The seed for the master random number generator
Default:0

C++ Type:unsigned int

Description:The seed for the master random number generator

- diag_save_inThe name of auxiliary variables to save this BC's diagonal jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)
C++ Type:std::vector

Description:The name of auxiliary variables to save this BC's diagonal jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

- implicitTrueDetermines whether this object is calculated using an implicit or explicit form
Default:True

C++ Type:bool

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

### Advanced Parameters

- vector_tagsnontimeThe tag for the vectors this Kernel should fill
Default:nontime

C++ Type:MultiMooseEnum

Description:The tag for the vectors this Kernel should fill

- extra_vector_tagsThe extra tags for the vectors this Kernel should fill
C++ Type:std::vector

Description:The extra tags for the vectors this Kernel should fill

- matrix_tagssystemThe tag for the matrices this Kernel should fill
Default:system

C++ Type:MultiMooseEnum

Description:The tag for the matrices this Kernel should fill

- extra_matrix_tagsThe extra tags for the matrices this Kernel should fill
C++ Type:std::vector

Description:The extra tags for the matrices this Kernel should fill

### Tagging Parameters

## Input Files

- modules/heat_conduction/test/tests/heat_conduction/3d_quadrature_gap_heat_transfer/second.i
- modules/combined/test/tests/gap_heat_transfer_convex/gap_heat_transfer_convex_sm.i
- modules/combined/test/tests/generalized_plane_strain_tm_contact/generalized_plane_strain_tm_contact.i
- modules/combined/test/tests/gap_heat_transfer_htonly/cyl3D.i
- modules/heat_conduction/test/tests/recover/recover.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/nonmatching.i
- modules/heat_conduction/test/tests/meshed_gap_thermal_contact/meshed_gap_thermal_contact.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/second_order.i
- modules/heat_conduction/test/tests/meshed_gap_thermal_contact/meshed_annulus_thermal_contact.i
- modules/combined/test/tests/gap_heat_transfer_convex/gap_heat_transfer_convex.i
- modules/combined/test/tests/gap_heat_transfer_htonly/gap_heat_transfer_htonly_test.i
- modules/heat_conduction/test/tests/heat_conduction/3d_quadrature_gap_heat_transfer/moving.i
- modules/combined/test/tests/gap_heat_transfer_htonly/gap_heat_transfer_htonly_rspherical.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/perfectQ9.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/perfectQ8.i
- modules/combined/test/tests/gap_heat_transfer_htonly/gap_heat_transfer_htonly_zr_test.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/moving.i
- modules/combined/test/tests/gap_heat_transfer_htonly/sphere3D.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/gap_conductivity_property.i
- modules/combined/test/tests/gap_heat_transfer_htonly/gap_heat_transfer_htonly_it_plot_test.i
- modules/combined/test/tests/gap_heat_transfer_htonly/cyl2D.i
- modules/heat_conduction/test/tests/heat_conduction/2d_quadrature_gap_heat_transfer/perfect.i
- modules/combined/test/tests/gap_heat_transfer_htonly/gap_heat_transfer_htonly_rz_test.i
- modules/combined/test/tests/gap_heat_transfer_radiation/gap_heat_transfer_radiation_test.i
- modules/heat_conduction/test/tests/heat_conduction/3d_quadrature_gap_heat_transfer/nonmatching.i
- modules/combined/test/tests/gap_heat_transfer_htonly/sphere2DRZ.i