Regarding data mapping for parallel coupling

precice-config_parallel.xml (2.6 KB)
precice-config_serial.xml (1.9 KB)


I’m doing FSI simulations for perpendicular flap case using an in-house fluid solver and FEniCS for structure. I did computations with Serial explicit and implicit methods but the results always diverge after 0.6 sec. Then I increased the Young’s modulus, increased solid density, decreased fluid density etc. but the simulation diverges after about 1 sec.

In my case as I have ‘read-consistent’ and ‘write-consistent’ due to which there is restriction to use parallel computation. I followed the example in this link and modified my precice-config file accordingly.

But I get this below warning, and also get force and displacement = inf throughout.
“preCICE:WARNING: The coupling residual equals almost zero. There is maybe something wrong in your adapter. Maybe you always write the same data or you call advance without providing new data first or you do not use available read data. Or you just converge much further than actually necessary.”

If that’s okay can someone let me know any mistake that I’ve done on my precice-config_parallel.xml file?

Thanks and regards,

These restrictions mainly tell us which participant should be computing which mapping. The type of the mapping (consistent/conservative) depends on the fields you are coupling.

Since you are exchanging forces, the respective mapping (from Fluid-Mesh to Solid-Mesh) must be a conservative mapping.

This is how your config currently looks like:


Another issue I see with a first look is that the Fluid-Mesh is not exchanged, as Force is exchanged via the Solid-Mesh.


  1. Make the mapping from fluid to solid conservative
  2. exchange Force over the Fluid-Mesh
  3. If you get the same error, move one of the mappings to the other participant, and change its direction

Dear Makis,
Thank you very much for your suggestions.

Sorry, I wasn’t clear earlier. My colleague had initially tried to exchange force with a conservative mapping but it resulted in accuracy issues on the boundaries of the coupling interface (first points and last points). This is why we started to work with pressure (and thus consistent mapping). But then realized that parallel coupling has some restrictions as it is both ‘read and write consistent’. I had followed your 3rd suggestion in my precice-config_parallel.xml file which I sent earlier. And now I tried with your 2nd suggestion but I still have the same error as before.


It works for me now, although results still diverge. I followed this linked which helped:



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