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 Restrict to layered edges check box makes the node applicable only if a layered material is defined on the edge. If a layered material (Material with Layer thickness specified, Single Layer Material, Layered Material Link, or Layered Material Stack) 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 Shell type is Nonlayered shell in the Shells Properties section of the parent interface or node, the Restrict to layered boundaries check box is not editable.
In addition, in 2D, edges are modeled as points and this section is named Point Selection, containing a Restrict to layered points check box.
Shell Properties
Different settings are available, depending on the settings in the Shell Properties section of the parent interface or node:
When the Shell type is Layered shell in the Shells Properties section of the parent interface, the same layered material is used in the Surface-to-Ambient Radiation node, but you can limit the contribution to individually selected layers by clearing the Use all layers check box. For a given Layered Material Link or Layered Material Stack, you get access to a list of check boxes for the selection of the individual layers.
When the Shell type is Nonlayered shell in the Shells Properties section of the parent interface or node, the Thickness is taken From physics interface (or From parent feature) in the Surface-to-ambient radiation node. You can change to User defined 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 Layer Cross Section Preview and Layer 3D Preview buttons.
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 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 Default 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 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.
Location in User Interface
Context Menus
Ribbon
Physics Tab with Thin Layer, Thin Film, or Fracture selected in the model tree:
Physics Tab with Heat Transfer in Shells selected: