Add a Continuity node to connect parts of an assembly using one or several Identity pairs. Both sides of the identity pair must be part of the physics interface in which you add the Continuity node.

Select a method to implement the continuity conditions: Classic constraints (default) or Nitsche. When classic constraints are selected, the continuity conditions are implemented as pointwise constraints on the destination side of the pair.

The Nitsche method implements the continuity condition in a weak sense by adding equations instead of constraints. If many other nodes that add constraints are present in the model, this has the advantage of not adding extra work for the constraint elimination algorithm of the solver. Moreover, the Nitsche method is often the more accurate method for connecting parts with nonconforming meshes at the shared boundary.

If Nitsche is selected, choose how to define the Stabilization factor — Automatic, Manual Tuning, or User defined. When Manual tuning is selected, enter a value for the Stabilization factor multiplier. This is a multiplier acting on the characteristic stiffness defined for all selected pairs. The stiffness is based on the material properties and the mesh element size on both sides of a pair. For User defined, enter an expression for the stabilization factor γ that will be used for all pairs.

Also, choose a Formulation — Symmetric, Skew-symmetric (default), or Nonsymmetric. This setting controls how the equations added to implement the continuity condition are written and can influence the robustness and performance of the solution. The default Skew-symmetric formulation is the most robust formulation, but is more expensive to use compared to the Nonsymmetric formulation. The Symmetric formulation has the advantage that it maintains the symmetry of the stiffness matrix, which can be important for large models.

It is also possible to select on which side to the pair to apply the continuity conditions by setting Apply on to either: Source and destination (default), Source, or Destination. It is generally recommended to apply the continuity conditions on the side with the finest mesh. However, the unbiased formulation obtained by the default Source and destination option is in the majority of cases equally accurate but can be more expensive.

Physics tab with Solid Mechanics or Multibody Dynamics selected: