To add a Generic Feature node ():

For information about the Dependencies window’s information about dependencies, see Dependencies.

The Settings window for a Generic Feature has the following sections:

The text entered in the Description field is the text COMSOL displays for the feature in the Model Builder. Click the Rename node using this text button () to update the node in the Physics Builder.

The Type is a unique string that identifies a feature and it must be unique among all features supported by a physics interface. The Default name and tag field is used to generate the tag of newly created instances in the Model Builder.

From the Allowed space dimensions list, define what space dimension this particular feature can be used with. Same as parent (the default) means that the feature supports the same space dimensions as the parent instance, which can either be a physics interface or another feature. Select Customized to control the space dimensions manually.

Special restrictions on study types can also be controlled for this feature. If you try to solve a problem for a feature that does not support the current study type, it does not add any contributions to the model. Choose Customized from the Allowed study types list to control the supported study types manually. The option Same as parent (the default) means that the feature supports the same study types as the parent.

The Supported geometric entity levels list specifies the level of the selection that the feature uses when adding all its contributions like variables, equations, and constraints. The choices in this list have a slightly different meaning compared to the top level you choose in the Top geometric entity level list of the physics interface settings (see Physics and Multiphysics Interfaces). The choices Same as top level (Domain condition) and One level below top level (Boundary condition) are relative to the top level of the interface. If the top level of the interface is Domain, choosing One level below top level (Boundary Condition) means that the feature contains a boundary condition to the governing equations. These boundary conditions then live on faces in 3D and lines (edges) in 2D. On the other hand, if the top level is Boundary, choosing One level below top level (Boundary Condition) still means that the feature contain boundary conditions, but the conditions now live on lines (edges) in 3D and points in 2D. For such shell interfaces, the governing equations are defined on faces in 3D and lines (edges) in 2D. The boundary condition to a line, for example, is a point. The choices Same as parent level and One level below parent level make the feature’s selection settings contain entities of the same geometric entity level or one level below (boundaries, if the parent level is domains, for example), respectively. The choices Edge and Point always refer to the geometric entities edge and point no matter what the top level is. For more details on geometric entity levels, see Selection Terminology.

Finally, if your interface has Global as Top geometric entity level, the relative choices, Same as top level (Domain condition) and One level below top level (Boundary condition), refers to the geometry dimension the global interface belongs to. If you add it to a 3D geometry, the entity levels becomes domains and faces. A global interface can also live on a global model (no geometry), and in this case it does not make sense to use anything else than the Global option. It is therefore recommended that you restrict the space dimensions of features that use any of the other options.

It is possible to limit the types of entities where a feature can be active. For example, a boundary condition can be limited to only interior boundaries. All other selected boundaries then get marked as not applicable. For more complex situations, you can use conditions on domain types to decide if a specific boundary is applicable or not.

Select a form of Applicable entities from the list: From entity types (the default) or From sequence.

Select an Override rule: Built in (the default), Locally defined, or Imported from external resource.

The Override type list specifies if the feature is Exclusive or Contributing to other features. In the Model Builder, an exclusive feature (such as constraints and fixed values) replaces all previous feature instances for intersecting selections whereas a contributing feature (such as loads and sources) adds to other contributing features sharing the same selection. You also select to only Override features of the same type or to let the feature be Never overridden.

In the Input base vector system list, you choose what coordinate system all user inputs and material parameters are given in. This is related to the frame type and is the coordinate systems to use for spatial vectors and matrices.

The Base vector system list specify the coordinate system used by the equations and variables declared by this feature. If any of these lists has the selection Selected input coordinate system, the user gets an option to choose coordinate system in the Settings window of the feature instance in the Model Builder.

The Frame type list specifies if the equations assumes that they live on the material or spatial frame. The options are Material (the default), Spatial, and Selectable by user. The latter means that the frame type can be controlled when using the feature instance. The instance then gets a Material type list with the options Solid, Nonsolid, or From material. The feature uses the material frame for the solids, and the spatial frame for nonsolids (typically a fluid such as a liquid or a gas).

Select the Singleton feature check box if the physics interface only allows a single instance of the feature.

A feature instance in the Model Builder can have a section called Model Inputs, which shows up when you select the Include model inputs check box. A model input is an input argument to material parameters when they depend on a quantity (for example, if the density depends on temperature).

For features under a physics interface there is an Add as default feature check box. Select this check box if you want the feature to be a default feature. When you specify default features, specify the geometric entity level in the Default geometric entity level list. Newly created interfaces then add the feature on this level. The Default entity types specifies the entity types the default feature is added on.

In the Advanced preferences table, you can specify special options for the default feature. By default, default features have a selection over all domains (it cannot be changed), and you can neither remove or disable the feature. Select the check box columns — Unlock selection, Clear selection, Deactivable, and Removable — to alter this default behavior. The last column, Lists order weight, is a preference to control the order of the default features. The standard order is domain features first, then boundary features, and so on until the point features followed by the global features. The automatically added initial value features always show up last in the list. The program uses a integer when sorting the default features. The integer depends on the geometric entity dimension and the list order weight using the following formula:

Do small adjustments (<100) to control order within an entity dimension, and large adjustments to put a default feature first or last in the list. Initial value features has a default weight of −1000 to appear last.

Select the Hide feature from context menus check box to remove the possibility to add new features of this type. This can be useful when a feature must be kept for backward compatibility reasons, but a user cannot add them in new models. When selected, this option also enables hiding with respect to the option Advanced Physics Options in the Show More Options dialog box in the Physics Builder. This is the only option there that represent a category in the Category for hiding feature list, which has the options Always hidden and Advanced physics options. Select Always hidden (the default) to hide it permanently, or select Advanced physics options to make it possible for users to show it by selecting Advanced Physics Options in the Show More Options dialog box.

Specify parameters by filling in the columns Name, Description, and Default expression.