COMSOL 6.4 - Weak Contribution

) under > in a model component to add a weak expression integrated on a selection to the overall system of equations.

The window contains the following sections:

Select the of the selection over which the weak expression is to be integrated. The default level is the level.

If the component where the weak contribution is added contains attached extra dimensions, optionally select a valid attached dimension from the list and specify a selection in the attached extra dimension. This will also filter the base selection, which will be applicable only where the extra dimension has been attached.

When the is set to , you can extend the selection to include all boundaries between individual mesh elements inside a domain selection. Note that the selection is specified on the domain level, but the resulting selection is still a boundary selection.

Enter a valid on the feature selection.

The default is , which uses a pattern of integration points in the interior of mesh elements. Choose instead to use a different pattern including points at mesh element nodes. These predefined patterns are constructed so that a polynomial of at most the specified will be integrated exactly. If you have added custom Integration Rule nodes under , these are also available in the setting.

For the and quadrature methods, choose a suggested or which will expose the expression field. The suggested even orders from 0 to 8 are available in all dimensions. The default is which is appropriate for a second-order equation using quadratic shape functions. An order entered as a user-defined parameter expression must evaluate to an integer, but may be odd. The maximum order depends on the space dimension. It is 30 in 2D and 14 in 3D.

Choose a frame from the list to set the volume element in the weak form integral. The default is .