Heat Source, Interface (Heat Transfer in Shells Interface)
This node models a heat source (or sink) on the exterior interfaces of a shell and, for the case of a layered shell, at the interfaces between its layers. It adds a heat source q = Qb or q = Pb ⁄ A. A positive q is heating and a negative q is cooling.
Boundary Selection
Select the boundaries on which to apply the heat source.
In addition, select the Restrict to layered boundaries check box to make the node applicable only if a layered material is defined on the boundary. 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 boundary index (for example, slmat1), otherwise the boundary is marked as not applicable.
Note that when the Shell type is Nonlayered shell in the Shells Properties section of the parent interface, the Restrict to layered boundaries check box is not editable.
Interface Selection
Set the interfaces for which the heat source contribution should be applied. These can be internal interfaces between layers or the top and bottom surfaces.
Different settings are available, depending on the settings in the Shell Properties section of the parent interface:
When the Shell type is Layered shell in the Shells Properties section of the parent interface, the available options in the Apply to list are Top interface, Bottom interface, Exterior interfaces, Interior interfaces, All interfaces, and Selected interfaces. With the last option you can select any set of interfaces for a given layered material, by clearing the check boxes corresponding to layer interfaces where the node should not be applied in the Selection table. The top and bottom interfaces refer respectively to the upside and downside of the boundary, defined from the orientation of the normal vector. See Interface Selections for more details on the interfaces identification.
When the Shell type is Nonlayered shell in the Shells Properties section of the parent interface, a single layer material is defined on the boundary, and the available options in the Apply to list are Top interface, Bottom interface, and All interfaces. This setting has no effect unless the temperature differs from one side of the boundary to the other.
You can visualize the selected interfaces by clicking the Layer Cross Section Preview and Layer 3D Preview buttons.
Upside and downside settings can be visualized by plotting the global normal vector (nx, ny, nz), that always points from downside to upside. Note that the normal vector (ht.nx, ht.ny, ht.nz) may be oriented differently.
See Tangent and Normal Variables in the COMSOL Multiphysics Reference Manual.
Material Type
Select an option in the Material type list to specify if the inputs of the Boundary Heat Source section are defined in the material or spatial frame:
The default option for the Heat Source node is Solid, which specifies that the heat source Qb is defined in the material frame. Because the heat transfer variables and equations are defined in the spatial frame, the inputs are internally converted to the spatial frame. See Conversion Between Material and Spatial Frames for details.
The Nonsolid option defines Qb in the spatial frame. No frame conversion is needed.
The From material option uses the option selected in the Material type list of the Material Properties section of the material applied on the domain on which the node is active.
Boundary Heat Source
Click the General source (default) or Heat rate button.
For General source, enter the boundary heat source Qb. A positive Qb is heating and a negative Qb is cooling.
For Heat rate enter the heat rate Pb. In this case Qb = Pb ⁄ A, where A is the total area of the selected layers interface.
In 2D components, the equation contains an additional factor, dz, to take into account the out-of-plane thickness. This is because the selected points correspond to edges in a 3D geometry.
Location in User Interface
Context Menus
Ribbon
Physics Tab with Heat Transfer in Shells selected in the model tree: