# Issues with Calculix-preCICE-InterFoam simulation when running Flap case in parallel

**URL:** <https://precice.discourse.group/t/issues-with-calculix-precice-interfoam-simulation-when-running-flap-case-in-parallel/2720>\
**Category:** Official adapters and tutorials\
**Tags:** openfoam, calculix, fsi\
**Created:** [February 9, 2026, 12:19pm UTC](https://precice.discourse.group/t/issues-with-calculix-precice-interfoam-simulation-when-running-flap-case-in-parallel/2720 "2026-02-09T12:19:51Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Alejo321](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Alejo321](https://precice.discourse.group/u/Alejo321)\
**Post date:** [February 9, 2026, 12:19pm UTC](https://precice.discourse.group/t/issues-with-calculix-precice-interfoam-simulation-when-running-flap-case-in-parallel/2720/1 "2026-02-09T12:19:51Z")

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Dears,

I was trying to run the flap case with interFoam and Calculix in parallel but it crashes after a while (~ 0.54 sec). If I run the model with only one processor (/fluid-openfoam/./run & /solid-calculix/./run) it completes the simulation with no problem. Nonetheless, the issues come when I try to use ./run-parallel with 4 cores. The simulation starts and run for a while, and then, an error occurs (**[precice] ERROR: Receiving data from another participant (using sockets) failed with a system error: read: End of file [asio.misc:2]. This often means that the other participant exited with an error (look there)**). I use OFv2412, Calculix 2.20 and the latest release for preCICE (V3.3.1).

From what I can understand, the parallel simulation seems unstable, the “largest residual force” is (10^(2)) and so Calculix does not converge.

See pictures attached:

Do you have some guidelines that could help me?

Thank you for your time.

 ![image](https://global.discourse-cdn.com/free1/uploads/precice/original/2X/5/5ef0ec7d0c5aa6fa33db9c4f0246ab28b47a4de3.png)

 ![image](https://global.discourse-cdn.com/free1/uploads/precice/original/2X/f/f4fa905df30a3fc0c819ad1a3e4736beec206d35.png)

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<div class="post-metadata">

**Author:** ![Makis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/makis/32/25_2.png) [@Makis](https://precice.discourse.group/u/Makis)\
**Post date:** [February 9, 2026, 1:55pm UTC](https://precice.discourse.group/t/issues-with-calculix-precice-interfoam-simulation-when-running-flap-case-in-parallel/2720/2 "2026-02-09T13:55:53Z")

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Hi @Alejo321,

thank you for reporting this, I can reproduce it. I opened an issue to collect more details:

> <https://github.com/precice/tutorials/issues/710>
>
> When running the \[breaking dam 2D tutorial\](https://precice.org/tutorials-breaki…ng-dam-2d.html) in parallel:
> 
> \`\`\`
> \# fluid-openfoam
> ./run.sh -parallel 
> 
> \# solid-calculix
> ./run.sh
> \`\`\`
> 
> the CalculiX participant crashes at t=0.6s. Reported by a user in the \[forum\](https://precice.discourse.group/t/issues-with-calculix-precice-interfoam-simulation-when-running-flap-case-in-parallel/2720).
> 
> \- Tutorials state (last commit / release): 9894b79305894d4ed8d78ec8c159cad5ab5768b5 (but much earlier versions should be relevant as well)
> \- Versions of solvers and adapters used: OpenFOAM v2512, OpenFOAM adapter f7e2d, CalculiX v2.20, CalculiX adapter 11993
> \- preCICE version: v3.3.1
> \- Log files:
> - \[fluid-openfoam.log\](https://github.com/user-attachments/files/25184745/fluid-openfoam.log)
> - \[solid-calculix.log\](https://github.com/user-attachments/files/25184751/solid-calculix.log)
> - \[precice-Solid-convergence.log\](https://github.com/user-attachments/files/25184757/precice-Solid-convergence.log)
> - \[precice-Solid-iterations.log\](https://github.com/user-attachments/files/25184758/precice-Solid-iterations.log)
> 
> \<img width="1508" height="911" alt="Image" src="https://github.com/user-attachments/assets/215c2bba-05d6-498f-84c3-612d6d04e893" /\>
> 
> I have not yet compared with the serial case, I will add more results once available.