# 7.14.2.3. Heat Flux Boundary Condition

Scope

  Aria Region, Equation System, Explicit Equation System, Root Finder Equation System

Summary

  This command block specifies that a known heat flux is to be applied normal to the given surface.

Description

  The flux can vary in arbitrary way, e.g. it may be a specified constant, a function of temperature, time etc. You may only specify one kind of flux e.g it is not legal to specify a constant value and a time dependent function. If you want to add two such fluxes on a single surface, then either write a user subroutine or use two different command blocks. If a function name is given then the function must be defined in a function definition command block.

    begin Heat Flux Boundary Condition Name

       Add Surface SurfaceList...

       Element Subroutine {=} Name

       Equation {=} EquationName

       Field Scaling {=} Scale_factor

       Flux {=} Value

       Flux Fortran Subroutine {=} Name

       Flux Node Variable {=} Name [ Multiplier {=} Value  ]

       Flux Scale Factor {=} Value

       Flux Temperature Function {=} Namep

       Flux Time Function {=} Name

       Flux Vector Node Variable {=} Name [ Multiplier {=} Value  ]

       Ignore Flux Coverage

       Influx Vector Node Variable {=} Name [ Multiplier {=} Value  ]

       Integer Data Values...

       Integrated Flux Output VariableName

       Integrated Power Output VariableName

       Real Data Values...

       Scaling Time Function {=} Function

       Scaling With Global Variable {=} name

       Use Data Block Name

       Use Toggle Block ToggleName [ {on} ElementBlockList...  ]

    end Heat Flux Boundary Condition Name

## 7.14.2.3.1. Line Commands

###### Add Surface

Syntax

  Add Surface SurfaceList…

Summary

  Adds surfaces, by name, to a boundary condition’s extent.

Description

  This line command is used to add surfaces to the extent of a boundary condition. In Exodus II, surfaces are specified as side sets, that have a global integer identifier. For example, side set 12 would be added by this line command using the surface name surface_12. Note that in SIERRA, each element of an array of strings must be separated by whitespace.

Parameter | Value | Default
--- | --- | ---
SurfaceList | string… | –

###### Element Subroutine

Syntax

  Element Subroutine {=} Name

Summary

  Specifies that the named user-defined subroutine be used. At most one subroutine name may be specified for a given quantity. This subroutine must conform to the “element signature” argument list type.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Name | string | –

###### Equation

Syntax

  Equation {=} EquationName

Summary

  This command can be used to apply the Heat Flux conditions for an equation other than the ENERGY equation.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
EquationName | string | –

###### Field Scaling

Syntax

  Field Scaling {=} Scale_factor

Summary

  This command is only relevant when the FLUX NODE VARIABLE, FLUX VECTOR NODE VARIABLE or INFLUX VECTOR NODE VARIABLE command line option is present. The command enables scaling of the Field by a single value for the surfaces defined within the scope of the current Heat Flux command block. For vector Fields all components will be scaled by the provided value.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Scale_factor | real | –

###### Flux

Syntax

  Flux {=} Value

Summary

  This line command specifies a constant value of heat flux.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Value | real | –

###### Flux Fortran Subroutine

Syntax

  Flux Fortran Subroutine {=} Name

Summary

  Specify the name of a FORTRAN user subroutine that will be used to calculate the flux boundary condition.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Name | string | –

###### Flux Node Variable

Syntax

  Flux Node Variable {=} Name [ Multiplier {=} Value ]

Summary

  Specify the name of the node variable to use for the flux that is associated with this boundary condition. Here the node variable is assumed to be the product of the surface unit normal vector with the nodal heat flux. Optionally, the value can be scaled by product of Multiplier value and FIELD SCALING.

Description

  The indicated node variable must be a legal Aria variable. In most cases this variable is defined by the user in the user variable definition command block. The node variable is interpolated to the quadrature points during the evaluation of flux term contributions. If need be, both the sign and magnitude of the node variable can be modified by using the FIELD SCALING command line. Typically, the node variable would be calculated in another SIERRA region, e.g., Fuego, and transferred to Aria.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Name | string | –

###### Flux Scale Factor

Syntax

  Flux Scale Factor {=} Value

Summary

  Specifies the magnitude by which the distribution factors will be multiplied in order to determine the boundary condition. If this line command is used, sideset distribution factors must be defined in the input mesh for all surfaces which are associated with this boundary condition.

Description

  The flux on each face is computed by interpolating the distribution factors to the Gauss points and then multiplying the result by the given magnitude. Distribution factors do not currently work with h–adaptivity, since their values are not currently interpolated to the new nodes.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Value | real | –

###### Flux Temperature Function

Syntax

  Flux Temperature Function {=} Namep

Summary

  Specifies the name of a temperature dependent heat flux function that is used to calculate the normal flux.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Namep | string | –

###### Flux Time Function

Syntax

  Flux Time Function {=} Name

Summary

  Specifies the name of a time dependent heat flux function that is used to calculate the normal flux.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Name | string | –

###### Flux Vector Node Variable

Syntax

  Flux Vector Node Variable {=} Name [ Multiplier {=} Value ]

Summary

  Specify the name of the vector node variable to use for the flux that is associated with this boundary condition. Here the flux contribution for a surface will be evaluated by forming a dot product of the unit normal vector with the vector node variable, without regard to the sign of the dot product. Optionally, the vector values can be scaled by product of Multiplier value and FIELD SCALING.

Description

  The indicated node variable must be a legal Aria vector variable. In most cases this variable is defined by the user in the user variable definition command block. The node variable is interpolated to the quadrature points during the evaluation of flux term contributions. If need be, both the sign and magnitude of the node variable can be modified by using the FIELD SCALING command line. Typically, the vector node variable would be calculated in another SIERRA region, e.g., Fuego, and transferred to Aria.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Name | string | –

###### Ignore Flux Coverage

Syntax

  Ignore Flux Coverage

Summary

  This command causes the code to ignore the flux coverage Field when contact is present. Thus the flux will be applied even if the BC is being set on a contact surface.

###### Influx Vector Node Variable

Syntax

  Influx Vector Node Variable {=} Name [ Multiplier {=} Value ]

Summary

  Specify the name of the node variable to use for the flux that is associated with this boundary condition. Here the applied flux will be formed by the dot product of the surface unit normal vector with the nodal variable which produce an influx contribution. Optionally, the value can be scaled by product of Multiplier value and FIELD SCALING.

Description

  The indicated node variable must be a legal Aria variable. In most cases this variable is defined by the user in the User Variable definition command block. The node variable is interpolated to the quadrature points during the evaluation of flux term contributions. If need be, both the sign and magnitude of the node variable can be modified by using the FIELD SCALING command line. Typically, the node variable would be calculated in another SIERRA region, e.g., Fuego, and transferred to Aria.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Name | string | –

###### Integer Data

Syntax

  Integer Data Values…

Summary

  List of integer data values to be used by the FORTRAN user subroutine. Copies of these values are provided to the subroutine hence changes to these values within the subroutine are not saved.

Parameter | Value | Default
--- | --- | ---
Values | integer… | –

###### Integrated Flux Output

Syntax

  Integrated Flux Output VariableName

Summary

  Calculate the average flux associated with this flux boundary condition.

Description

  This line command specifies that, as a postprocess, the normal flux associated with this boundary condition be integrated over the surface to obtain the total power. This power is then divided by the total area of the surface to obtain the average flux on the surface, and stored in a global variable named “VariableName”. This global variable may then be output to history files, or accessed in user subroutines, etc.

Parameter | Value | Default
--- | --- | ---
VariableName | string | –

###### Integrated Power Output

Syntax

  Integrated Power Output VariableName

Summary

  Calculate the total power associated with this flux boundary condition.

Description

  This line command specifies that, as a postprocess, the normal flux associated with this boundary condition be integrated over the surface to obtain the total power which is then stored into a global variable named “VariableName”. This global variable may then be output to history files, or accessed in user subroutines, etc.

Parameter | Value | Default
--- | --- | ---
VariableName | string | –

###### Real Data

Syntax

  Real Data Values…

Summary

  List of real data values to be used by the FORTRAN user subroutine. Copies of these values are provided to the subroutine hence changes to these values within the subroutine are not saved.

Parameter | Value | Default
--- | --- | ---
Values | real… | –

###### Scaling Time Function

Syntax

  Scaling Time Function {=} Function

Summary

  This command is only relevant when the FLUX NODE VARIABLE, FLUX VECTOR NODE VARIABLE or INFLUX VECTOR NODE VARIABLE command line option is present. This command enables time function scaling of the field variable for the surfaces defined within the scope of the current Heat Flux command block.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Function | string | –

###### Scaling With Global Variable

Syntax

  Scaling With Global Variable {=} name

Summary

  This command is only relevant when the FLUX NODE VARIABLE, FLUX VECTOR NODE VARIABLE or INFLUX VECTOR NODE VARIABLE command line option is present. The command enables scaling of the Field by a global variable for the surfaces defined within the Heat Flux command block. For vector Fields all components will be scaled by the named scalar global variable. The scalar global variable itself must be defined at the Region scope as type Real with length 1.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
name | string | –

###### Use Data Block

Syntax

  Use Data Block Name

Summary

  Reference to predefined data to be used by the user subroutine. These values may be changed by the user subroutine.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Use Toggle Block

Syntax

  Use Toggle Block ToggleName [ {on} ElementBlockList… ]

Summary

  Specification for toggling entities in the computational model based on Toggle Block parameters. When used at the region level, the list of element blocks to be toggled must be provided. Otherwise a listing of entities is not needed as the Toggle Block will be associated with the command line or the enclosing command block.

Parameter | Value | Default
--- | --- | ---
ToggleName | string | –