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 the Isothermal domain check box is selected under Physical Model section, you can add more Isothermal domain Interface nodes if needed.

If this node is selected from the Pairs menu, choose the pair on which to apply this condition. A pair has to 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 (the default), Continuity, Ventilation, Convective 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 (the 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.

Either the Heat transfer coefficient h or the Thermal conductance hth 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.

Either the Thermal resistance, Rt or the Absolute thermal resistance, Rt, th 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.

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 compute 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 the Ambient Settings section of a Heat Transfer or Heat Transfer in Shells interface.

This section is only available when the Surface-to-surface radiation check box is selected under the Physical Model section on the parent physics interface.

Select Opaque (the default) or Transparent to set the interface’s opacity type.

This is needed when the interface contributes with any boundary condition from the Radiation menu. It picks the side where irradiation starts from.

If the Isothermal domain check box is selected under the Physical Model section:
Heat Transfer>Isothermal Domain Interface
Heat Transfer in Solids>Isothermal Domain Interface
Heat Transfer in Fluids>Isothermal Domain Interface
Heat Transfer in Porous Media>Isothermal Domain Interface
Bioheat Transfer>Isothermal Domain Interface
Heat Transfer with Surface-to-Surface Radiation>Isothermal Domain Interface
Heat Transfer with Radiation in Participating Media>Isothermal Domain Interface

Physics Tab with interface as Heat Transfer, Heat Transfer in Solids, Heat Transfer in Fluids, Heat Transfer in Porous Media, Heat Transfer in Building Materials, Bioheat Transfer, Heat Transfer with Surface-to-Surface Radiation or Heat Transfer with Radiation in Participating Media selected:
Boundaries>interface>Isothermal Domain Interface
Pairs>interface>Isothermal Domain Interface