This node adds several conditions for temperature exchange at the interfaces of an isothermal domain. It can be applied on interior and exterior boundaries of the computational domain, except on the boundaries found inside a single isothermal domain.
In addition to the default Isothermal domain Interface node always present when an
Isothermal domain feature is added, you can add more
Isothermal domain Interface nodes if needed.
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.
If this node is selected from the Pairs menu, choose the pair to apply this condition to. A pair must be created first. See
Identity and Contact Pairs in the
COMSOL Multiphysics Reference Manual for more details.
The available Interface type options are
Thermal insulation (default),
Continuity,
Ventilation,
Convective heat flux,
Nucleate boiling heat flux, and
Thermal contact. Depending on the
Interface type selected from the list, further settings are required.
The available Flow direction options are
Positive normal direction (default),
Negative normal direction, and
Both sides. For each option, either the
Mass flux or the
Mass flow rate should be specified:
The External temperature found under the section of the same name must be set when the isothermal domain interface is also an exterior boundary.
When the Heat transfer coefficient h option is selected, the default option is to enter a
User defined value for the
Heat transfer coefficient h.
In addition, the following options are also available to control the type of convective heat flux to model: External natural convection,
Internal natural convection,
External forced convection, or
Internal forced convection. A complete description of these options can be found in
Heat Flux,
Convective Heat Flux.
The External temperature found under the section of the same name must be set when the isothermal domain interface is also an exterior boundary. For internal boundaries, the external temperature is defined as the temperature of the adjacent domain.
The heat flux q0 is computed with the Rohsenow’s correlation, that evaluates the heat flux due to nucleate boiling on a surface immersed in a liquid pool. See
Nucleate Pool Boiling Correlation for details about the correlation. This option is intended to be used on an exterior boundary and considers the
Isothermal Domain to be the solid. It has no effect on interior boundaries. Select materials from the
Fluid and
Surface lists. When a predefined material (
Water,
Benzene,
n-Pentane, or
Ethanol) is used for the fluid, no additional parameters are required, because the liquid and vapor properties are predefined (at saturation temperature) and the Rohsenow’s correlation parameters
Csf and
s are available for different surface materials. Else, see
Nucleate Boiling Heat Flux (
Heat Flux feature) for details about the settings.
Either specify the Surface thermal resistance,
Rt,s (SI unit: K·m
2/W), or set the
Thermal resistance,
Rt (SI unit: K/W) and evaluate
Rt,s from it:
where A (SI unit: m
2) is the surface area of the boundary.
The External temperature found under the section of the same name must be set when the isothermal domain interface is also an exterior boundary.
This section is not available if the Interface type is set to
Thermal Insulation or
Continuity. Else, the
External temperature,
Text should be specified. It is used to calculate the heat exchange with the exterior by the
Ventilation,
Convective heat flux, and
Thermal contact options on isothermal domain interfaces that are also exterior boundaries. The value is ignored on interior boundaries.
For User defined, enter a value or expression for the
Temperature Text. Else, select an
Ambient temperature defined in an
Ambient Properties node under
Definitions.
Select Opaque (default) or
Transparent to set the interface’s opacity type.
The Constraint settings can be set to
Pointwise constraints (default) or
Weak constraints. Select
Weak constraints to replace the standard constraints with a weak implementation.