When coming into the Meshing/Mechanical application, by default, connections are found between parts that have faces in proximity of each other. This automatic detection of connections or interfaces can be disabled if it is not desired. The Auto Detect Contact On Attach can be changed by selecting from the Ansys Workbench main menu, and then selecting either the Mechanical or Meshing category as appropriate. The option is enabled by default in both applications.
These contact regions can be used for mesh sizing, and/or are used to define the behavior on how the contact/interface is treated when running the simulation.
For structural solvers see the description of connections in the Ansys Mechanical help.
For CFD solvers, contact regions are used differently by the Ansys CFX and Ansys Fluent solvers:
Contact regions are used in Ansys CFX as General Grid Interface (GGI) definitions. For details, refer to the documentation available under the Help menu within CFX.
Contact regions are used in Ansys Fluent as mesh interfaces. See Special Cases for details.