Body Couplings
Body couplings model the different types of connection between 6-DOF bodies or between a 6-DOF body and the environment. For each body coupling, an extra force is generated on each of the associated bodies.
You add body couplings according to the connections in the real scenario. An example is shown below:

Body couplings and 6-DOF bodies can be visualized through a DFBI displayer. An example of two boats connected through a catenary (towing line) is shown below:

For more details, refer to Setting up DFBI Post-Processing.
Simcenter STAR-CCM+ provides the following types of body couplings: