Surface-to-Ambient Radiation (Thin Layer, Thin Film, Fracture, and Heat Transfer in Shells Interface)

Use this subnode to add surface-to-ambient radiation to lines (geometrical edges in 3D or geometrical points in 2D and 2D axisymmetric) that represent thin boundaries of a thin layer, a thin film, or a fracture.

The net inward heat flux from surface-to-ambient radiation is

where ε is the surface emissivity, σ is the Stefan-Boltzmann constant (a predefined physical constant), and Tamb is the ambient temperature.

Edge Selection

Select the edges on which to add surface-to-ambient radiation. The check box makes the node applicable only if a layered material is defined on the edge. If a layered material ( with specified, , , or ) is available, its name is then displayed beside the edge index (for example, slmat1), otherwise the edge is marked as not applicable.

Note that when the is in the section of the parent interface or node, the check box is not editable.

In addition, in 2D, edges are modeled as points and this section is named , containing a check box.

Shell Properties

Different settings are available, depending on the settings in the Shell Properties section of the parent interface or node:

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When the is in the section of the parent interface, the same layered material is used in the node, but you can limit the contribution to individually selected layers by clearing the check box. For a given or , you get access to a list of check boxes for the selection of the individual layers.

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When the is in the section of the parent interface or node, the is taken (or ) in the node. You can change to and override the parent node setting with a specific value or expression for Lth.

You can visualize the selected layered materials and layers in each layered material by clicking the and buttons.


	The desired selection for the node may correspond to boundaries with different layered materials. See Layered Material, Layered Material Link, Layered Material Stack, Layered Material Link (Subnode), and Single-Layer Materials in the COMSOL Multiphysics Reference Manual.

Model Input

This section contains fields and values that are inputs for expressions defining material properties. If such user-defined property groups are added, the model inputs appear here.

Temperature

This section is available when material properties are temperature-dependent. By default, the temperature of the parent interface is used and the section is not editable. To edit the field, click (

). The available options are (default), (the minput.T variable, set to 293.15 K by default) and all temperature variables from the physics interfaces included in the model. To edit the minput.T variable, click the button (

), and in the node under , set a value for the in the section.

Surface-to-Ambient Radiation

Ambient Temperature

For , enter an Tamb. The default value is approximately room temperature, 293.15 K (20ºC). Else, select an defined in an node under .

Surface Emissivity

The default ε (a dimensionless number between 0 and 1) is taken . For , it should be specified. An emissivity of 0 means that the surface emits no radiation at all while an emissivity of 1 means that it is a perfect blackbody.

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Thin Layer (Heat Transfer Interface) and Solid (Heat Transfer in Shells Interface)

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Thin Film (Heat Transfer Interface) and Fluid (Heat Transfer in Shells Interface)

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Fracture (Heat Transfer Interface) and Porous Medium (Heat Transfer in Shells Interface)

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Theory for Heat Transfer in Thin Structures

Location in User Interface

Context Menus

Ribbon

Physics Tab with , , or selected in the model tree:

Physics Tab with selected: