Heat Source (Heat Transfer in Shells Interface)

This node models a linear heat source (or sink). It adds a heat source q = Qb or q = Pb ⁄ A. A positive q is heating and a negative q is cooling.

Edge Selection

Select the edges on which to apply the heat source. 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 interface, 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 interface:

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When the is in the section of the parent interface, the same layered material is used in the node, 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 interface 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 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 default option for the node is , 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.

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The option defines Qb 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.

Boundary Heat Source

Select an option from the list:

For (default), enter the boundary heat source Qb. A positive Qb is heating and a negative Qb is cooling.

For enter the heat rate Pb. In this case Qb = Pb ⁄ A, where A is the total area of the selected edges (where A is the product of the layer’s thickness ds by the total length of the selected edges).


	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.


	You can specify the source to be a harmonic perturbation in a frequency domain analysis. To mark the source as being a harmonic perturbation, right-click the node and choose Harmonic Perturbation. Note that this updates the node’s icon. See Theory for Harmonic Heat Transfer for more details.

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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

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Physics tab with selected: