Named Selections
Introduction
This section details how to create named selections to reuse throughout the model component when assigning material properties, boundary conditions, and other model settings.
You can create selection nodes under the Component node’s Definitions node to represent various parts of the geometry and simplify the process of assigning materials, model equations, boundary conditions, and other model properties. These user-defined selections can be reused during modeling and named using descriptive titles — for example, Tube, Wall, or Fluid. Changes to the selection (for example, by adding or removing a boundary) updates all nodes in the Component that use that particular selection. You can also use a named selection to create a certain parts of the geometry that you want to hide from the view (see Hide for Physics).
Use the buttons listed in Table 6-2 to create, copy, and paste selections. When there is the possibility of overlapping geometric entities, it is recommended that you use The Selection List Window to ensure the correct part of the geometry is selected.
There are different types of selections: Explicit selections, selections by enclosing part of the geometry by a bounding Ball, Box, or Cylinder, Boolean selections (Union, Intersection, Difference, and Complement), and selections of Adjacent geometric entities. To add selection nodes, Click Selections () on the Definitions toolbar or right-click a Definitions node and choose from the Selections options as listed in Table 6-6.
You can also click Selections () on the Geometry toolbar or right-click a Geometry node and choose from Selections options listed in Table 6-7 for defining selections based on the geometry objects in the geometry sequence. See Creating Named Selections in the Geometry Sequence. These selections can be used in the geometry sequence as well as when setting up the physics.
For meshes that define their own geometric model, on the Mesh toolbar, click Selections () or right-click a Mesh node and choose from Selections options listed in Table 6-8 for defining selections based on the geometry objects in the geometry sequence. See Creating Named Selections in the Mesh Sequence. These selections can be used in the meshing sequence as well as when setting up the physics.
The selections can be highlighted using a color scheme to make it easier to see the geometric entities that are included in a named selection. See Selection Colors.
Open an Example Model with Defined Selections
Figure 6-17 uses a COMSOL Multiphysics Application Library example, which includes several user-defined selections.
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Navigate to the COMSOL Multiphysics>Geometry_Tutorials\steam_reformer_geometry model file. Double-click to open it.
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Expand the Geometry 1 node under Component 1. Several nodes display in the Model Builder. Click the nodes shown in Figure 6-17 to examine how they are set up and to see which entities they select. Open the documentation for the tutorial for a detailed description of how to set up the selections.
Open the The Selection List Window to quickly see the available selections for each entity level.
For Selections with explicit selections, in the selection Settings windows, click the Zoom to Selection () button to zoom in on the selected geometric entities.
Figure 6-17: An example of an Intersection Selection. The selection nodes can be renamed by the user. The Selection List lists all available named selections for the selected geometric entity level.
The Types of Named Selections