Thin Film (Heat Transfer interface) and Fluid (Heat Transfer in Shells interface)
This node behaves like Fluid but is applicable on boundaries.
Layer Selection
Select the applicable layers (the default setting is All layered materials) defining the required material properties for the node.
If no layered materials have been included yet, there is a shorthand available for creating a Single Layer Material, a Layered Material Link, or a Layered Material Stack (the plus, next to the Layered Material list).
When a layered material stack or link is selected from the Layered Material list, unselect the check boxes corresponding to layers where the node should not be applied in the Selection table.
You can visualize the selected layered materials and layers in each layered material by clicking the Layer cross section preview and Layer 3D preview buttons.
Note that this section is not editable when Fluid is the default node of the Heat Transfer in Shells interface.
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.
Model Input
This section has fields and values that are inputs to expressions that define material properties. If such user-defined property groups are added, the model inputs appear here.
Temperature
This section is available when temperature-dependent material properties are used. 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 Common Model Inputs node under Global Definitions, set a value for the Temperature in the Expression for remaining selection section.
Absolute Pressure
The absolute pressure is used in some predefined quantities that include the enthalpy (the energy flux, for example).
It is also used if the ideal gas law is applied. See Thermodynamics, Fluid.
The default Absolute pressure pA is User defined. When additional physics interfaces are added to the model, the absolute pressure variables defined by these physics interfaces can also be selected from the list. For example, if a Laminar Flow interface is added you can select Absolute pressure (spf) from the list. The Common model input option corresponds to the minput.pA variable, set to 1 [atm] by default. To edit it, click the Go to Source button (), and in the Common Model Inputs node under Global Definitions, set a value for the Pressure in the Expression for remaining selection section.
Velocity Field
The default Velocity field u is User defined. For User defined enter values or expressions for the components based on space dimensions. Or select an existing velocity field in the component (for example, Velocity field (spf) from a Laminar Flow interface). The Common model input option corresponds to the minput.u variable. To edit it, click the Go to Source button (), and in the Common Model Inputs node under Global Definitions, set values for the Velocity components in the Expression for remaining selection section.
Layer Model
The available options for Layer type are Thermally thin approximation and General. The former is a lumped model that accounts only for tangential temperature gradients (along the film), whereas the latter accounts also for the normal gradients of temperature (through the film’s thickness). The second model may be used for the modeling of bearings for example.
Within a layered material selection, a single Layer type should be used. If two layer types are needed for the same layered material, the original material should be duplicated so that one layered material is defined for each layer type. A Shell Continuity (Heat Transfer interface) and Continuity (Heat Transfer in Shells Interface) node may be added between the two layered materials.
The settings for the Model Input, Heat Conduction, Fluid, and Thermodynamics, Fluid sections are the same as for Fluid.
Location in User Interface
Context menus
Heat Transfer in Fluids>Thin Film
Heat Transfer in Films>Fluid
Ribbon
Physics Tab with interface as Heat Transfer in Fluids selected:
Boundaries>Thin Film
Physics Tab with interface as Heat Transfer in Films selected:
Boundaries>Fluid