Heat Flux (Thin Layer, Thin Film, Fracture)

Use thissubnode to add heat flux across boundaries of a thin layer, a thin film or a fracture. A positive heat flux adds heat to the layer.

Edge Selection

Select the edges on which to apply the heat flux. 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 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 node:

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When the is in the section of the parent node, the same layered material is used in the node. This option is not editable, 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, the is taken 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.

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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.

Material Type

Select an option in the list to specify if the inputs of the section are defined in the material or spatial frame:

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The option specifies that the heat flux 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 subnode is , which defines q0 in the spatial frame. No frame conversion is needed.

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The option uses the option selected in the list of the 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 take into account 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

Click the (default), , or (3D components only) button.

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If is selected, it adds q0 to the total flux across the selected edges. Enter a value for q0 to represent a heat flux that enters the layer. For example, any electric heater is well represented by this condition and its geometry can be omitted.

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If is selected, it adds q0 in the form q0 = h ⋅ (Text − T). Enter the h and the Text. This latter value depends on the geometry and the ambient flow conditions. For , enter a value or expression. Else, select an defined in an node under .

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3D Components: If is selected, it adds q0 in the form q0 = P0 ⁄ A where A is equal to the area of the edge selection. Enter the heat rate P0.

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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

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Handling Frames in Heat Transfer

Location in User Interface

Context Menus

Ribbon

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