Hi,everyone.I meet some problems that I can not slove in FSI.As you can see in the log, it seems that everthing is OK.However, the P residuals can not drop . Corresponding to this, the exporting data of stress has many oscillations.Could someone help me slove it. Thanks a lot. 
Hi jialin, from the single configuration file we couldn’t easily tell what’s wrong there.
If you still have this problem, it would be helpful for the analysis when you provide more information about the results from other preCICE configurations(esp. with different acceleration parameters) that you might have tried and if they helped or not. For example, try with other acceleration method, different filter type in current method or freeze the pre-conditioner after some time steps etc.