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.
Layer Selection
Select the applicable layers (the default setting is All layered materials) defining the required material properties for the node.
If no layered materials have been included yet, there is a shorthand available for creating a Single Layer Material, a Layered Material Link, or a Layered Material Stack (the plus, next to the Layered Material list).
When a layered material stack or link is selected from the Layered Material list, unselect the check boxes corresponding to layers where the node should not be applied in the Selection table.
You can visualize the selected layered materials and layers in each layered material by clicking the Layer cross section preview and Layer 3D preview buttons.
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For a general description of layer and interface selections, see The Layer Selection and Interface Selection Sections.
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You can provide material parameters with a through-thickness variation by explicitly or implicitly using expressions containing the extra dimension coordinate as described in Using the Extra Dimension Coordinates.
The desired selection for the node may correspond to boundaries with different layered materials. The All layered materials option allows to gather these materials to make the desired selection applicable for the node on the union of the boundaries where the layered materials are defined.
See Layered Material, Layered Material Link, Layered Material Stack, Layered Material Link (Subnode), and Single Layer Material in the COMSOL Multiphysics Reference Manual.
Model Input
This section has fields and values that are inputs to expressions that define material properties. If such user-defined property groups are added, the model inputs appear here.
Temperature
This section is available when temperature-dependent material properties are used. By default the temperature of the parent interface is used and the section is not editable. To edit the Temperature field, click Make All Model Inputs Editable (). The available options are User defined (default), Common model input (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 Go to Source button (), and in the Common Model Inputs node under Global Definitions, set a value for the Temperature in the Expression for remaining selection section.
Surface-to-Ambient Radiation
Ambient temperature
For User defined, enter an Ambient temperature Tamb. The default value is approximately room temperature, 293.15 K (20ºC). Else, select an Ambient temperature defined in an Ambient Thermal Properties node under Definitions.
Surface emissivity
The default Surface emissivity ε (a dimensionless number between 0 and 1) is taken From material. For User defined, 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
 Heat Transfer in Solids>Thin Layer>Surface-to-Ambient Radiation
Heat Transfer in Solids>Thin Film>Surface-to-Ambient Radiation
Heat Transfer in Porous Media>Fracture>Surface-to-Ambient Radiation
 Heat Transfer in Shells>Surface-to-Ambient Radiation
Ribbon
Physics Tab with Thin Layer, Thin Film, or Fracture selected in the model tree:
Attributes>Surface-to-Ambient Radiation
Physics Tab with Heat Transfer in Shells selected:
Egdes>Surface-to-Ambient Radiation