A model component is a fundamental part of the model and contains a geometry with its associated physics interface, mesh, and variables and other definitions that are local to that component. The Component node defines the namespace for each part of a model that is defined in a model component. A model can have several Component nodes. For example, if you are setting up a system model using both a 2D simplification — represented in one 2D Component branch — and a full 3D description in another Component, these can both be added to the Model Builder to represent different aspects or parts of the model. You can couple variables between different components in a model using coupling operators.

The Component node icon also indicates the space dimension:.

You can create models with multiple geometries by adding one or more Component nodes to the Model Builder. Typically a component is added to the model in the Model Wizard when you select a space dimension.

To add a Component node or nodes:

To copy a component with all its subnodes, right-click the Component node and choose Copy (or, for Windows users, click Copy on the Quick Access Toolbar). You can then paste it in the same or a new COMSOL Desktop session by right-clicking the root node and choosing Paste Multiple Items (or, for Windows users, click Paste Multiple Items on the Quick Access Toolbar).

It is also possible to insert components from another COMSOL Multiphysics model. To do so, right-click the top node (root node) and choose Insert Components from Model. An Insert Components dialog box appears where you can browse or type the path and name of the COMSOL Multiphysics model file from which you want to insert components in the Model field. Select one or more of the components in the model from the Components list and then click OK to insert them into the current model.

Altogether, these aspects may cause an insert or paste operation to be incomplete to some degree. In some cases, the difference is reported in a message dialog box after the insertion process has finished. Click Cancel in this dialog box to revert the insertion process.

In a model with more than one component, you can switch the focus to another component by selecting from the list of components in the Home toolbar’s Model section. You can also switch to another component by clicking its Component node in the model tree (or any other node inside that component).

These default nodes are normally added under a Component node:

The Settings window has the following sections (also see Figure 3-3):

The label appears on the node as the default node name. The default label is Component 1, but you can change it in the Label field.

The name is a string used to define a namespace for the model component and identify variables defined in that component. The default component name is comp1, comp2, and so on, but you can change it in the Name field. See Settings and Properties Windows for Feature Nodes and Displaying Node Names, Tags, and Types in the Model Builder for more information.

The default setting in the Unit system list, Same as global system, is to use the global unit system, which you specify in the root node’s Settings window. If you want to use another unit system in a model, select it from this list.

Underneath, you can define the coordinates for the frames in a model if you do not want to keep the default names. All frames are always defined. See About Frames for more information about frames.

For Spatial frame coordinates, the default names are x, y, and z for 3D as well as planar 1D and 2D geometries. For axisymmetric geometries, the default names for the spatial frame coordinates are r, (phi), and z. If you use the geometry to represent something other than space, or if you for some other reason want to use other names for the spatial coordinates, you can change the names in the fields for the First, Second, and Third coordinate under Spatial frame coordinates.

For Material frame coordinates, the default names are X, Y, and Z for 3D as well as planar 1D and 2D geometries. For axisymmetric geometries, the default names for the material frame coordinates are R, (PHI), and Z. You can change the names in the fields for the First, Second, and Third coordinate under Material frame coordinates.

For Geometry frame coordinates, the default names are Xg, Yg, and Zg for 3D as well as planar 1D and 2D geometries. For axisymmetric geometries, the default names for the geometry frame coordinates are Rg, (PHIg), and Zg. You can change the names in the fields for the First, Second, and Third coordinate under Geometry frame coordinates.

For Mesh frame coordinates, the default names are Xm, Ym, and Zm for 3D as well as planar 1D and 2D geometries. For axisymmetric geometries, the default names for the mesh frame coordinates are Rm, (PHIm), and Zm. You can change the names in the fields for the First, Second, and Third coordinate under Mesh frame coordinates.

The setting in the Geometry shape order list determines the order of the curved mesh elements that determine the geometry shape. The default setting is Automatic, but it is also possible to select an order such as Linear, Quadratic, Cubic, Quartic, Quintic, Sextic, and Septic. The default setting allows for automatic reduction of the order in some cases.

By default, the software avoids inverted elements by an optimization of the element shapes. To deactivate that functionality, clear the Avoid inverted elements by curving interior domain elements check box. See Avoiding Inverted Mesh Elements for more information.