Associative Geometry and Selections of Geometry Objects
Associative geometry is a concept for the automatic updating of applied physical properties, such as boundary conditions and equation coefficients, under geometric transformations. Thus, once you have defined the physical properties of a model and return to the Geometry branch to modify the geometric model, COMSOL Multiphysics updates the physical properties according to the geometry modifications. The associative geometry functionality uses geometry-mapping information between the groups of geometric entities (points, edges, boundaries, and domains) in the finalized geometry and the corresponding groups in the geometric model.
This geometry mapping is not always without ambiguities. COMSOL Multiphysics makes some heuristic decisions when mapping the physical properties between the finalized geometry (the object on which the physical properties are imposed) and the geometric model. In some cases, the resulting updated physical properties might not be the ones that are expected.
User-defined named selection nodes in the geometry sequence are useful to improve associativity compared to other selection nodes (see Creating Named Selections in the Geometry Sequence). You can refer to such selections defined in following geometry nodes (for example, as input objects). This applies both to selections of resulting entities in previous geometry nodes and selections created by selection nodes.