The Heat Transfer in Fractures Interface
The Heat Transfer in Fractures (htlsh) interface (), found in the Thin Structures physics area under the Heat Transfer branch (), is used to model heat transfer by conduction, convection, and radiation in layered materials represented by boundaries. The interface is active on all boundaries where a layered material is defined, with a Porous Medium model active by default. All functionalities for including other boundary contributions, such as surface-to-ambient radiation, are also available.
Layered Material Link, together with a Layered Material node
Layered Material Stack, together with one or several Layered Material nodes
Material, with the Layer thickness property specified
See Layered Material, Layered Material Link, Layered Material Stack, Layered Material Link (Subnode), and Single Layer Materials in the COMSOL Multiphysics Reference Manual for details on the definition of layered materials.
Although the layered material is represented as a boundary in the model, the through-thickness variation of the temperature is accounted for. It means that the temperature equation, corresponding to the convection-diffusion equation with thermodynamic properties averaging models to account for both solid matrix and fluid properties, is solved also in the layered material’s thickness direction. This equation is valid when the temperatures into the porous matrix and the fluid are in equilibrium, and may contain additional contributions such as heat sources.
In addition, a single boundary may represent several layers with different thermal properties varying through the thickness of the layered material. This uses the Extra Dimension tool which defines the equations on the product space between the boundary and the additional dimension for the thickness of the layered material. See Modeling Layered Materials for details.
For thermally thin boundaries, it is possible to bypass the use of the product space, by selecting Nonlayered shell in the Shell type list, and setting a user defined value for the Thickness Lth directly in the interface. A lumped formulation assuming that heat transfer mainly follows the tangential direction of the boundary is then available.
See Theoretical Background of the Different Formulations for a description of the different formulations.
The physics interface is available for 2D components, 3D components, and for axisymmetric components with cylindrical coordinates in 2D.
When this version of the physics interface is added, these default nodes are also added to the Model Builder: Porous Medium, Thermal Insulation (an edge condition), and Initial Values. Then, from the Physics toolbar, add additional nodes that implement, for example, boundary interface or edge conditions, and heat sources. You can also right-click Heat Transfer in Fractures to select physics features from the context menu.
Boundary Selection
See Boundary Selection for a description this section, common to all versions of the Heat Transfer in Shells interface.
Shell Properties
See Shell Properties for a description this section, common to all versions of the Heat Transfer in Shells interface.
Physical Model
See Physical Model for a description of the Reference temperature setting under the Physical Model section.
Consistent Stabilization
This section is available by clicking the Show More Options button () and selecting Stabilization in the Show More Options dialog box. See Consistent Stabilization for more details.
Inconsistent Stabilization
This section is available by clicking the Show More Options button () and selecting Stabilization in the Show More Options dialog box. See Inconsistent Stabilization for more details.
Discretization
See Discretization for more details.
Temperature
By default, the shape functions used for the temperature are Linear. This setting affects also the discretization of the temperature field in the thickness direction.
Dependent Variables
See Dependent Variables for details.
See Settings for the Heat Transfer in Shells Interface for a description of the other settings.