# CoupledConvectiveHeatFluxBC

Convective heat transfer boundary condition with temperature and heat transfer coefficent given by auxiliary variables.

This boundary condition computes convective heat flux , where is convective heat transfer coefficient, is the temperature solved for, and is far field temperature. Both and are spatially varying variables.

A typical use case for this boundary condition are coupled multi-apps exchanging heat flux.

It is possible to use vector coupling to compute the heat flux for multi-phase fluids. In this case, users need to supply alpha parameter, which represents the volume fraction for each phase. Similarly, multiple components have to be supplied for htc and T_infinity. The number of components for alpha, Hw and T_infinity must match. The heat flux is then computed as .

[./right]
type = CoupledConvectiveHeatFluxBC
variable = u
boundary = right
alpha = 'alpha_liquid alpha_vapor'
htc = 'Hw_liquid Hw_vapor'
T_infinity = 'T_infinity_liquid T_infinity_vapor'
[../]

(modules/heat_conduction/test/tests/heat_conduction/coupled_convective_heat_flux/coupled_convective_heat_flux_two_phase.i)

## Input Parameters

• variableThe name of the variable that this boundary condition applies to

C++ Type:NonlinearVariableName

Options:

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

Options:

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

• htcHeat transfer coefficient

C++ Type:std::vector

Options:

Description:Heat transfer coefficient

• T_infinityField holding far-field temperature

C++ Type:std::vector

Options:

Description:Field holding far-field temperature

### Required Parameters

• alpha1.0Volume fraction of components

Default:1.0

C++ Type:std::vector

Options:

Description:Volume fraction of components

### Optional Parameters

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

Options:

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

Options:

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

Options:

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

Options:

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

Options:

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

Options:

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

Options:

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

• vector_tagsnontimeThe tag for the vectors this Kernel should fill

Default:nontime

C++ Type:MultiMooseEnum

Options:nontime time

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

Options:

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

Options:nontime system

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

Options:

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