Use a Circle () node to add a circle to a geometry, as shown in Figure 7-25.

To add a Circle () node, choose one of the following:

When you have added a node or finished drawing the circle in the Graphics window, you can use the following section to define it or fine-tune it.

From the Type list, select Solid (default) or Curve to specify if the circle is a solid object (disk) or a curve object.

From the Defined by list, select Size and position (default) to specify the radius and position for the circle. Select Bounding disk (approximate) to create a disk that approximately bounds a selection of objects or entities. A bounding disk is useful to replace a complicated imported object with a circle, or to create a fluid domain around objects.

From the Center list, select Centroid (default) to let the position be determined by a centroid measurement of the input entities, or select Manual to manually specify the position.

This section is shown if Defined by is set to Size and position. Define the circle’s radius in the Radius field. Enter a sector angle (in degree) for a circle sector in the Sector angle field. The default value is 360 degrees for a full circle.

This section is shown if Defined by is set to Bounding disk (approximate). From the Geometric entity level list, choose the level of the entities to bound: Object (default), Domain, or Boundary, or Point. From the Selection list, choose Manual (default) to select the geometry objects or entities that you want to bound in the Graphics window. If the geometry sequence includes user-defined selections above the Circle node, you can choose one of the selections from the Selection list. Click the Activate Selection button to toggle between turning ON and OFF the Input objects selections. Alternatively, choose All objects to select all objects or choose All nonconstruction objects to automatically select all objects that have not been marked as Construction Geometry.

For the setting Geometric entity level: Object, select the checkbox Keep input objects (selected by default) to keep the objects that are bounded. Clear the checkbox to delete the selected objects.

This section is shown if Defined by is set to Bounding disk (approximate). Fill in the Margin edit field to enlarge the bounding disk (or shrink it if the value is negative).

From the Base list, choose Center (default) if the circle is centered about the position, or choose Corner if a surrounding box has a corner at the position. For Position type set to Coordinates (default), enter the position using the x and y fields. For Vertex, select a point in the Graphics window. Click the Activate Selection button to toggle between turning ON and OFF the Position selections.

Specify the counterclockwise rotational angle about the position in the Rotation field. The default angle is 0 degrees.

Layers can be used to create sandwich primitives by adding several concentric circles, as shown in Figure 7-26. This is especially useful when specifying artificial domains in the physics, such as Infinite Element Domains and Perfectly Matched Layers. You specify the thicknesses of layers in the Layers table, and optionally a name for each layer. The outermost layer comes first. Each layer must have a minimal thickness (depending on the size of the geometry).

Select the Create Parameters checkbox to automatically create parameters for the coordinates and size of the circle to be used in further geometry creation, mesh size settings, or physics set up. The created parameters can be seen in the variable tree that appears when pressing Ctrl+Space in an edit field in another feature. If the 2D geometry is set up using constraints and dimensions, use Measuring Dimensions and Dimension Parameters instead.

Select the Resulting objects selection checkbox to create predefined selections (for all levels — objects, domains, boundaries, and points — that are applicable) in subsequent nodes in the geometry sequence. To also make all or one of the types of resulting entities (domains, boundaries, edges, and points) that the circle consists of available as selections in all applicable selection lists (in physics and materials settings, for example), choose an option from the Show in physics (Show in instances if in a geometry part; Show in 3D in a plane geometry under a work plane in a 3D component) list: All levels, Domain selection, Boundary selection, or Point selection. The default is Domain selection, which is suitable for use with materials and physics defined in domains. For use with a boundary condition, for example, choose Boundary selection. These selections do not appear as separate selection nodes in the model tree. Select Off to not make any selection available outside of the geometry sequence. From the Color list, choose a color for highlighting the resulting objects selection. See Selection Colors.

When the Layers table is nonempty, select the Create layer selections checkbox to create predefined domain selections for each specified layer and for the core domain. To also make the domains available as selections in all applicable selection lists (in physics and materials settings, for example), select the Show in physics (Show in instances if in a geometry part or Show in 3D if in a Plane Geometry) checkbox (ON by default).

If you want to make the resulting entities contribute to a cumulative selection, select a cumulative selection from the Contribute to list (the default, None, gives no contribution), or click the New button to create a new cumulative selection (see Cumulative Selections).

Select the Construction geometry checkbox to make the resulting objects available only in the feature’s geometry sequence. For more information, see Construction Geometry.