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.

Layer Selection

Select the applicable layers (the default setting is ) defining the required material properties for the node.

If no layered materials have been included yet, there is a shorthand available for creating a , a , or a (the plus, next to the list).

When a layered material stack or link is selected from the list, unselect the check boxes corresponding to layers where the node should not be applied in the table.

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 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.

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 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

Click the (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 ⁄ L where L is equal to the length 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: