COMSOL 6.2 - Geometry Operations

Geometry Operations

This section describes the available geometry operations (Work Plane Operations, Boolean and Partition Operations, Transform Operations, Conversion Operations, Other Geometry Operations, and Programming). The features in Table 7-5, Table 7-6, Table 7-7, Table 7-8, and Table 7-9,are also available as buttons on The Geometry Toolbar.


	See Virtual Geometry and Mesh Control Operations for examples of how to use virtual geometry operations to remove a short edge and to ignore and collapse edges to prepare the geometry for efficient meshing. You can use several of these operations to also control the mesh.

Work Plane Operations

The following table lists operations available with work planes in 3D geometries:

Table 7-5: Work plane related Operations for 3D models.
Icon	Name	Description
	Cross Section	Create a 2D cross section from an intersection between a 3D geometry and a work plane.
	Extrude	Extrude planar objects into 3D.
	Revolve	Revolve planar objects into 3D.
	Sweep	To sweep one or several faces along a spine curve.
	Work Plane	Create a work plane for drawing 2D objects that are embedded in 3D.

Boolean and Partition Operations

Use Boolean and Partition operations to create a composite geometry object by forming unions, set differences, and set intersections — and combinations of those operations — of existing geometry objects.

The following Boolean and Partitions operations are available in all space dimensions:

Table 7-6: Boolean and Partition Operations.
Icon	Name	Space Dimension	Description
	Compose	1D, 2D, 3D	Compose geometry objects by specifying Boolean operations using a set formula.
	Difference	1D, 2D, 3D	Select the objects to compose in the Graphics window and click the Difference button to take the selected object with the largest volume (area, length) and subtract the others.
	Intersection	1D, 2D, 3D	Select the objects to intersect in the Graphics window and click the Intersection button to create an intersection of the selected objects.
	Partition Domains	2D, 3D	Partition selected domains using lines or edges.
	Partition Edges	2D, 3D	Partition selected edges at specified locations.
	Partition Faces	3D	Partition selected faces at specified locations.
	Partition Objects	1D, 2D, 3D	Partition geometry objects using a work plane or other geometry objects (tool objects).
	Union	1D, 2D, 3D	Select the objects to unite in the Graphics window and click the Union button to create a union of the selected objects.

Transform Operations

You can use the transforms to create rectangular and linear arrays of identical geometry objects and to move, rotate, mirror, scale, and make rigid transformations geometry objects. Mirroring, moving, rotating, and scaling are affine transformations applied to geometry objects. All transforms are available in all space dimensions, except Rotate, which is not applicable for 1D geometries, and Rigid Transform, which is only applicable in 3D.

Table 7-7: Geometry Transform Operations.
Icon	Name	Space Dimension	Description
	Array	1D, 2D, 3D	Create an array of geometry objects.
	Copy	1D, 2D, 3D	Copy geometry objects.
	Mirror	1D, 2D, 3D	Mirror geometry objects in a plane (3D), a line (2D), or a point (1D).
	Move	1D, 2D, 3D	Move geometry objects.
	Rigid Transform	3D	Perform a rigid transformation of geometry objects.
	Rotate	2D, 3D	Rotate geometry objects about a centerpoint.
	Scale	1D, 2D, 3D	Scale geometry objects about a centerpoint.

Conversion Operations

The geometry conversion operations make it possible to, for example, convert a 3D solid to a surface (boundary) object for modeling a shell or other thin structure. You can perform the following geometry object conversions:

For 2D models:

•

Convert a solid object into a curve or point object.

•

Convert a curve object defining at least one closed domain into a solid object.

•

Convert a curve object into a point object.

For 3D models:

•

Convert a solid object into a surface, curve, or point object.

•

Convert a surface object defining at least one closed domain into a solid object.

•

Convert a surface object into a curve or point object.

•

Convert a curve object into a point object.

Table 7-8: Geometry Conversion Operations.
Icon	Name	Space Dimension	Description
	Convert to Curve	2D, 3D	Select the objects to convert in the Graphics window and click to unite them and convert them to a curve object.
	Convert to Point	1D, 2D, 3D	Select the objects to convert in the Graphics window and click to unite them and convert them to a point object.
	Convert to Solid	1D, 2D, 3D	Select the objects to convert in the Graphics window and click to unite them and convert them to a solid object.
	Convert to Surface	3D	Select the objects to convert in the Graphics window and click to unite them and convert them to a surface object.
	Convert to COMSOL	3D	Available with the CAD Import Module. Select the objects to convert in the Graphics window, and then click to convert them to a COMSOL kernel representation. See the CAD Import Module User’s Guide.
	Midsurface	3D	Convert a solid object to a surface object. Midsurface is available with the Design Module, see the Design Module User’s Guide.
	Split	1D, 2D, 3D	Split one or several objects into their entities.
	Thicken	2D	Convert 2D curve objects to solid objects by giving them a thickness in the normal direction. Thicken in 3D is available with the Design Module, see the Design Module User’s Guide.

Other Geometry Operations

For 2D geometry objects, you can use geometry operations such as fillets and tangents to construct the geometry. In all space dimensions you can delete geometry objects or geometric entities (domains, boundaries, edges, and points).

The following table provides an overview of available general geometry operations:

Table 7-9: Other Geometry Operations.
Icon	Name	Space Dimension	Description
	Chamfer	2D	Create chamfers at a set of corners of a 2D geometry object.
	Fillet	2D	Create fillets at a set of corners of a 2D geometry object.
	Extract	1D, 2D, 3D	Extract the selected entities into separate objects of corresponding entity level, or extract an object to delete all other objects.
	Offset	2D	Offset, in the normal direction, the edges of 2D curve objects
	Tangent	2D	Create a tangent from an edge to another edge or point in a 2D geometry.
	Delete Entities	1D, 2D, 3D	To delete geometric entities (domains, boundaries, edges, or points) from the objects they belong to, or to delete entire geometry objects, select the entities or objects and click the Delete button. If you delete objects corresponding to primitive features, these nodes are removed from the sequence. If you delete other objects or geometric entities, a Delete Entities node is added to the sequence. If instead you use the Delete Entities context menu item, a Delete Entities always displays.
	Edit Object	2D	To edit a 2D object using the Settings window, in the Model Builder, right-click the Geometry node and select Edit Object from the context menu. To edit a 2D object using the Graphics window, select the object and click the Edit Object button. See Editing 2D Geometry Objects.
	Import	1D, 2D, 3D	Import geometry objects from a file or from another geometry.
	Export	1D, 2D, 3D	Export geometry objects to file. See Exporting a Geometry.
	Insert Sequence	1D, 2D, 3D	Insert a geometry sequence from an MPH-file. See Inserting a Sequence.

Parts

You can use parts to simplify the geometry modeling with custom parts that can be reused and created as part instances in a geometry sequence:

Table 7-10: Parts.
Icon	Name	Description	see
	Part Libraries	Open the Part Libraries window.	Part Libraries
	Create Part	Create a global part of the same dimension as the current component.	Using Geometry Parts
	Load Part	Load parts from another MPH-file.	Using Geometry Parts
	Part Instance	Create a part instance in the current geometry or part.	Part Instance

Selections

You can add Named Selections in the Geometry sequence to simplify the geometry modeling and set up physics:

Table 7-11: Parts.
Icon	Name	Description	see
	Selections	Menu to add selections to the Geometry sequence.	Creating Named Selections in the Geometry Sequence
	Selection List	Opens the Selection List window.	The Selection List Window
	Colors	Menu to control the selection colors.	Selection Colors

Programming

You can use If, Else If, Else, and End If nodes to create If statements that enable or disable other features depending on values of logical conditions in terms of parameters. The Parameter Check node makes it possible to check the value of parameters (for example, to limit the value of an input parameter).

Table 7-12: Programming and Logical Operations.
Icon	Name	Description	See
	If	Begin an If statement.	If, Else If, Else, End If
	Else If	Continue an If statement.
	Else	Last alternative in an If statement.
	End If	End an If statement.
	Parameter Check	Check the value of parameters.

Evaluate

Use the following actions and operations to evaluate the geometric entities and objects:

Table 7-13: Parts.
Icon	Name	Description	see
	Measure	Measure the volume, area, perimeter, or other geometric properties of the selected geometric objects or entities. The result appears in the Messages window.	Measuring Geometry Objects and Entities
	Centroid Measurement	Create parameters that measure the centroid of selected vertices.	Centroid Measurement
	Distance Measurement	Create parameters that measure the distance between selected geometric entities.	Distance Measurement