A feature can have one Auxiliary Settings node () that contains a collection of various settings for its parent feature that you usually do not need to change.

Auxiliary Settings nodes can be added to the parent Features nodes under the Building Blocks branch, or to the features added under a Physics Interface or Multiphysics Interface. Right-click the Auxiliary Settings node to add Geometric Nonlinearity, Physics Symbol, and Usage Condition subnodes.

The Settings window has the following sections:

Enter a valid image file name in the Icon field to use a different icon for the feature. If this field is empty, the feature uses a default icon, which is different depending on the feature’s entity level.

This section provides possibility to include model inputs to a built-in property group in the Model Builder. Click the Select Quantity button () to open the Physical Quantity dialog box, from which you can choose a physical quantity to add as a model input. Use the other buttons under the table to arrange and edit the table of model inputs if required.

Select the Always visible check box to make the model inputs ignore the materials so that they always appear in the Settings window of the feature instance.

Select the Auto matched check box to specify that the model input can be automatically matched by the feature input framework.

Select the Use common model input by default check box to specify that the model input use the Common model input option by default for its list selection. Otherwise, the User defined option will be used.

Under GUI options, make the following settings to control the visibility of the Model Input section:

From the Category for hiding section list, choose None, Advanced physics options (the default), Equation-based contributions, or Stabilization.

The Section is initially collapsed check box is selected by default. Clear it to show the Model Input section initially in an expanded state.

This section contains settings that affect the entities on which the physics feature is applicable. The setting in the Take selection from list controls the maximum selection from which the feature can take its selection. That is the selection that is further restricted by the Applicable entities setting of the physics feature. The default option, Parent, means that the selection should be taken from the physics or in the case of a subfeature from the parent feature. Physics means that the selection should be taken from the physics even in the case of a subfeature. The last option, Geometry, indicates that the feature should take its selection from the entire geometry.

The other settings are the Not applicable on infinite element domain, Not applicable on absorbing layer domain and Not applicable on perfectly matched layer domain check box. Select any of these check boxes to make sure that the physics feature cannot be applied on a domain of the particular type.

When any of the base vector systems choices of the parent physics feature are Selected input coordinate system, this section has settings that control the input coordinate system. First, there is a Coordinate section list with the options Add coordinate system section (the default) and Use parent’s coordinate systems section. The latter choice disables all other settings and uses the Coordinate System Selection section from the parent if there is any. The Add coordinate system section option adds a Coordinate System Selection section to the physics feature. It also enables a couple of other settings that control this section. Select the Only allow orthonormal systems check box to only allow the user to choose between orthonormal systems when selecting the input coordinate system of the feature. Select the Only user-defined systems check box to only allow the user to choose between user-defined systems when selecting the input coordinate system of the feature. In the Filtering of systems list, choose between the options Allow boundary systems, No boundary systems, and Only boundary systems. Note that the filtering only affects features that live on the boundary geometric entity level.

This section has the settings Enable load groups and Enable constraint groups which can be selected to make the physics feature compatible with the Load cases functionality of COMSOL Multiphysics. When load- or constraint groups are enabled for a feature it gets extra menu-items so that the user can select under which group it is active. To make the physics feature useful under load grouping the variables that should be affected by the grouping need to have the Include in load groups setting selected in the Variable declaration node. Constraints are by default affected by the constraint grouping. If a particular constraint should not be affected by the grouping, then select the Exclude from constraint grouping setting in the Constraint node.

Select the Perturbation method from the list that has the following options:

You can choose Last in list (the default), First in list, or After features of type (regular expression) in the Position in list for new features list. For After features of type (regular expression) you can add a regular expression to set to position it after some specific feature types (such as Boundary* for all types that begin with Boundary).