The Constraint boundary condition specifies an expression
R which is constrained to be equal to zero on the selection,
R = 0. By default, this is a bidirectional constraint, meaning that all variables in
R are affected by reaction terms. You can also add
Constraint nodes for edges in 3D components and for points in 2D and 3D components by right-clicking the main PDE interface node and choosing
Constraint from the
Edges and
Points submenus.
Enter a value or expression for the value of R in the constraint
R = 0. For example, to constrain
u to
2, enter
2-u in the field for
R. The default value,
0, does not add any constraint.
To display this section, click the Show More Options button (
) and select
Advanced Physics Options in the
Show More Options dialog box.
Normally these settings do not need to be changed. This section contains settings for specifying the type of constraint and whether to use a pointwise or weak constraint. See
Constraint Settings for more information.