In a Work Plane node’s
Plane Geometry sequence you can add a
Cross Section node (
![](images/comsol_ref_geometry.14.062.1.png)
). By default, this computes the cross section of all 3D objects generated by preceding nodes in the geometry sequence. You can also select specific 3D objects to intersect with the work plane. You can also add a new 2D or 2D axisymmetric
Component and add the
Cross Section node there. In that case, you can select which
Work Plane to use. For example, if you have a 3D geometry that is symmetric about an axis, you can add a work plane that contains the axis. In the axisymmetric 2D Component, you then get the cross section and can use a 2D axisymmetric component, which is computationally efficient compared to a full 3D component. A
Cross Section node can also be useful to extract a planar surface for modeling a thin flat 3D structure using shell elements, for example. Another use for a cross section is to form a surface that you can extrude into a 3D solid from a closed curve that lie in a plane. Then also add a
Convert to Solid node below the
Cross Section node to make the closed curve into a 2D surface.
To add a cross section, right-click a Plane Geometry node under a
Work Plane node or a 2D
Geometry node and select
Cross Section (
![](images/comsol_ref_geometry.14.062.2.png)
). Then enter the properties of the cross section using the following sections:
If you add the Cross Section node to a 2D or 2D axisymmetric geometry, first select the work plane to use for the cross section from the
Work plane list.
From the Intersect list, choose
All objects (the default) to intersect all 3D geometry objects with the work plane, or choose
Selected objects to intersect only the geometry objects that you add to the
Objects to intersect list that appears. Click the
Active button to toggle between turning ON and OFF the
Objects to intersect selections.
You can change the settings for the Repair tolerance list if you experience problems with the cross section operation. Geometric entities that have a distance less than the repair tolerance are merged.
Select the Resulting objects selection check box to create predefined selections (for all levels — objects, domains, boundaries, edges, and points — that are applicable) in subsequent nodes in the geometry sequence. Use the
Show in 3D list (for
Cross Section nodes in a
Work Plane node’s
Plane Geometry) or the
Show in physics list (or
Cross Section nodes in 2D or 2D axisymmetric geometries) to choose for which geometric entity level the selection should be created. All applicable levels, as well as
All levels and
Off, are available. From the
Color list, choose a color for highlighting the resulting objects selection. See
Selection Colors.
Select the Selections from 3D check box to create selections in 2D based on the selections from the 3D geometry. Each selection that is produced by a 3D geometry feature preceding the work plane in the 3D geometry sequence and each 3D cumulative selection are intersected with the work plane to give a selection in 2D. These selections are available if the
Cross Section node under a Plane Geometry node in a work plane or under a 2D component’s
Geometry node. In the latter case, you can also select the
Show in physics check box to make the selections from 3D available in physics and materials settings, for example.