Reply To: Problem in the coupling of fluent and transient structural

[Stephen Orlando]

I recommend going over this tutorial in the Ansys documentation that shows a 2-way FSI simulation with Fluent and Mechanical. Have you done this tutorial yet? https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v221/en/sysc_tut/sysc_tut_reedvalve_fluent.html
The following tutorial, specifically this section: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v221/en/sysc_tut/sysc_tut_oscplate_export_cfx_setup_export.html, 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. https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v221/en/sysc_tut/sysc_tut_oscplate_export_cfx.html
FSI simulations with very soft materials 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: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v221/en/sysc_ug/sysc_gen_scservice_dt_supplemental_iqnils.html
It is very important to build up the FSI simulation in stages as opposed to setting up the 2-way FSI right at the start. This document "Best Practices for Coupled Fluid-Structure Interaction (FSI)" describes this process and is available here: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v221/en/sysc_ug/sysc_bestpractices_fsi.html
Steve