Heat Flux, Interface (Heat Transfer in Shells Interface)
This node adds a heat flux q0 on the exterior interfaces of a shell and, for the case of a layered shell, at the interfaces between its layers.
Boundary Selection
Select the boundaries on which to apply the heat flux.
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 flux 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:
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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, 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 details about the interfaces identification.
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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.
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For a general description of layer and interface selections, see Layer and Interface Selection Tools.
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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.
See Layered Material, Layered Material Link, Layered Material Stack, Layered Material Link (Subnode), and Single-Layer Materials in the COMSOL Multiphysics Reference Manual.
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 Heat Flux section are defined in the material or spatial frame:
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The Solid option specifies that the heat fluxes q0 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.
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The default option for the Heat Flux node is Nonsolid, which defines q0 in the spatial frame. No frame conversion is needed.
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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.
This option has no effect when the component does not contain a moving frame because the material and spatial frames are identical in such cases. With a Deformed Geometry or a Moving Mesh interface, the heat transfer features automatically account for deformation effects of the material and spatial frames on heat transfer properties. In particular the effects of volume changes on the density are considered. See Handling Frames in Heat Transfer and Material and Spatial Frames for details.
Heat Flux
These settings are the same as for the Heat Flux node.
In 2D the heat flux contribution is multiplied by dz to account for the out-of-plane thickness.
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Theory for Heat Transfer in Thin Structures
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The Heat Transfer Coefficients
Location in User Interface
Context Menus
Heat Transfer in Shells>Interfaces>Heat Flux, Interface
Heat Transfer in Films>Interfaces>Heat Flux, Interface
Heat Transfer in Fractures>Interfaces>Heat Flux, Interface
Ribbon
Physics Tab with Heat Transfer in Shells selected in the model tree:
Boundaries>Heat Flux, Interface