COMSOL 6.4 - Free Shape Boundary

The feature (

) can be added from the model tree under using the context menu. The selection of the feature has to be adjacent to a . The feature includes the following settings:

Continuity

When the is , the normal vector will be fixed at edges (points in 2D) between the feature and the feature. The option allows only fixing the normal at some of the relevant edges.

Similarly, when the is , no kinks will be introduced on edges (points in 2D) between different features, assuming that the boundaries are initially joined continuously.

Preserve Continuity of Normals over Symmetry Boundaries

This section only appears when is (see previous section).

Coordinate System

Select the among the features in the component. This section is only visible when the is .

Control Variable Settings

Choose between the types

•

, which enforces the maximum displacement strictly

•

, which confines the displacement to a box with side length equal to twice the maximum displacement.

•

, which confines the displacement to a box with custom dimensions.

The default value for the field is 5% of the geometry bounding box.


	A large value can give rise to error messages such as that in Figure 3-1.

Filtering

Pick a , , or filter radius Rmin, corresponding to 1, 1.5, and 2 times the dmax. Alternatively, you can set a filter radius and enter a custom value in the associated test field (default: 10% of the geometry bounding box). A small value can give rise to error messages such as that in Figure 3-1.

Figure 3-1: This error message is a sign that the dmax parameter is too large or the Rmin variable is too small.

Control Variable Initial Value

You can set an initial value d0 for the control variable field that is different from zero, but oftentimes it is better to modify the initial geometry directly instead.