MFX 2 way thermal FSI
 

Hello everybody,
I often have to apply very low under-relaxation factors (e.g. 0.1) for the Heat Flux being sent from CFX to Ansys in a MFX coupling and rather large factors for temperature and displacement (e.g. 0.75). What is the exact numerical or physical explanation for the instability that arises from higher under-relaxation factors with regard to the heat flux?
Best & Thx,
MK