after the interesting conversation during the latest preCICE community hour, I’d like to share my configuration and to see if there is something that could be improved.
As a short recap, I am working on an MBDyn adapter and I’m using it to couple beam elements in a FSI coupling. Up to now I have managed to replicate the Turek Hron benchmark results for the FSI2 benchmark (some results are in this post: preCICE adapter for MBDyn solver for beam elements).
- FSI2 converges quite slowly (mainly at the beginning many iterations are needed)
- At the beginning I need to apply a ramp to the loads applied to the structure. It looks to me that the slope of the ramp is crucial for convergence (if too steep the simulation diverges), much more than the type of ramp (linear or 0.5\cdot(1-\cos))
- I am using serial-implicit coupling with solid as first participant. this configuration works much better than other kinds of coupling
- IQN-ILS seems the best acceleration
- filter type QR1 outperforms QR2, as the residuals keep reducing over iterations
- I am using the same Fluid configuration as the OpenFOAM-CalculiX tutorial
I’d like to share my configuration file precice-config.xml (3.8 KB) . My goal would be to improve convergence time and to make the FSI3 benchmark converge.