Ansys Employee
Thanks for the clarification.
When running System Coupling and it stops running, the first thing to do is examine the output files for each solver to look for clues to what happened. For Fluent, look at the transcript .trn file. For Mechanical, look at the .out file. For CFX, look at the .out file. Also, look at the System Coupling log file, .scl. You can also try re-running the case and stopping it just before the timestep when it crashes, then examine the mesh in Fluent or CFD-Post to get more clues.
FSI simulations with very soft materials (like an elastic tube) or membranes are prone to numerical instabilities. In 2020R1 we have introduced a stabilization method in System Coupling called the Quasi-Newton Stabilization Algorithm. Note that this has to be used with the new System Coupling GUI or Command Line Interface that is run outside of Workbench. More information here:
The following tutorial, specifically this section:, shows how to set up a System Coupling case in Workbench and then export it to the new System Coupling GUI outside of Workbench. The new System Coupling GUI gives you access to more advanced features like Quasi-Newton Stabilization. This tutorial is for CFX and Mechanical, but the same export process, and System Coupling GUI setup process is valid for Fluent and Mechanical cases.