Geometry Representation

The component of the COMSOL Multiphysics® software that is used to represent, build, and manage the interactions between geometric objects is the geometric kernel or geometric modeler. There are two kernels used by the software, the COMSOL kernel, and the CAD kernel (the Parasolid® kernel) that is included with the CAD Import Module, the Design Module, and LiveLink™ products interfacing CAD packages.

With a license for the CAD Import Module the software defaults to the CAD kernel for representing the geometry. You need to use the CAD kernel to apply the geometry features included with this module, for example the defeaturing and repair tools, as well as to import 3D geometries using various 3D CAD file formats.

The 3D operations and primitives listed in Table 2-1 do not support the CAD kernel — they always use the COMSOL kernel. However, an automatic conversion is performed for these objects before they are used as input to geometry features that require the CAD kernel, see Converting Objects to CAD Kernel Representation.

Table 2-1: 3D geometry features that do not support the Parasolid geometry kernel.
Feature Name	Feature Name
Bezier Polygon	Point
Eccentric Cone	Polygon
Extrude	Pyramid
Helix	Revolve
Hexahedron	Sweep
Interpolation Curve	Tetrahedron
Parametric Curve	Torus
Parametric Surface	Work Plane

Changing the Geometric Kernel

To switch between geometric kernels, you can click the node, then in its Settings window, from the list choose either the or .

When you change the setting, all nodes that support the CAD kernel are marked as edited with an asterisk (*) in the upper-right corner of the node’s icon. To rebuild the geometry using the new kernel, click the button (

). To avoid re-solving an already solved model, you can click the button (

) in the toolbar to map the solutions from the geometry represented by the CAD kernel to the new geometry represented by the COMSOL kernel.


	If you solve a model using the CAD kernel, it is not possible to view and postprocess the solution if you open it in a COMSOL Multiphysics session where a license for the CAD Import Module, Design Module, or one of the LiveLink for CAD products is not available, unless, before saving the model, you change the geometry representation to COMSOL kernel and update the solution. This is possible to do only for 3D geometry sequences that do not contain geometry features that require the CAD kernel.

When you create a new model, its default geometry representation is controlled by the preference setting .

When you open an existing model, you normally use the geometry representation used in the model. To always get the possibility to convert the geometry to the COMSOL kernel, change the preference setting to .