Thermal Contact, Interface (Heat Transfer in Shells Interface)
Use this node to specify thermal contact at the internal interfaces between the layers of a layered shell. The surfaces asperities of the interfaces and the fluid gap between these surfaces are represented by an equivalent thin layer, for which the thermal conductance should be specified. This node is available only when the Shell type is Layered shell in the Shells Properties section of the parent physics interface.
Boundary Selection
Select the boundaries on which to specify the thermal contact. 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.
Interface Selection
Set the interfaces for which the thermal contact should be prescribed. These can be only internal interfaces between layers.
The available options in the Apply to list are Interior interfaces and Selected interfaces. With the second option you can select any set of internal 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. See Interface Selections for more details on the interfaces identification.
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 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.
Model Input
This section contains fields and values that are inputs for expressions defining material properties. If such user-defined property groups are added, the model inputs appear here.
Temperature
This section is available when material properties are temperature-dependent. By default, the temperature of the parent interface is used and the section is not editable. To edit the Temperature field, click Make All Model Inputs Editable (). The available options are User defined (default), Common model input (the minput.T variable, set to 293.15 K by default) and all temperature variables from the physics interfaces included in the model. To edit the minput.T variable, click the Go to Source button (), and in the Default Model Inputs node under Global Definitions, set a value for the Temperature in the Expression for remaining selection section.
Thermal Contact
The available options to specify the resistive behavior of the gap are Gap resistance (default), Gap conductance, and Gap thermal conductivity and thickness. Depending on the selected option, enter values or expressions for the Gap resistance, Req, the Gap conductance, heq, the Gap thermal conductivity, keq, and the Gap thickness, ds.
Radiative Conductance
The radiative conductance should be considered at high temperatures, above 600°C. Choose the Radiative conductance: User defined (default) or Gray-diffuse parallel surfaces. For User defined enter a value for hr.
Radiative Conductance
This section is available when Gray-diffuse parallel surfaces is selected as the Radiative conductance under Thermal Contact.
By default the Surface emissivity, upside and the Surface emissivity, downside, εu and εd, are taken From material. For User defined enter another value or expression.
Theory for Thermal Contact
Location in User Interface
Context Menus
Heat Transfer in Shells>Interfaces>Thermal Contact, Interface
Heat Transfer in Films>Interfaces>Thermal Contact, Interface
Heat Transfer in Fractures>Interfaces>Thermal Contact, Interface
Ribbon
Physics tab with Heat Transfer in Shells selected in the model tree:
Boundaries>Thermal Contact, Interface