A coupling problem between Openfoam and Calculix

Using preCICE
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Hello everyone, I am trying to use Openfoam and Calculix to calculate a three-dimensional flexible plate problem. I set the total duration of fluid solver, structural solver, and precision coupling to 5 seconds with a fixed time step of 0.0001 seconds. When I finally calculated to 4.9999s, the following issues occurred with the structural terminal:

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11920×1440 365 KB

As far as I know, this situation should occur when the solver’s solving time step is 0 or very close to 0. But I have been using fixed time steps all along, and I also calculated 4.9999s before. I don’t know what the problem is or what I set up to cause it. I need your help, thank you.

I am using Openfoam v2112 (Openfoam-adapter 1.3.0)、Calculix 2.20、precice-3.1.1.
The following are the controlDict files, and inp input files for Openfoam and Calculix.
controlDict.txt (1.6 KB)
precice-config.xml (2.5 KB)
new_flap_3d_1.inp (1.2 MB)

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preCICE takes control over the total duration of the coupled analysis, so you can set both OpenFOAM an Calculix to run longer than 5 seconds and preCICE will shut them down at the appropriate time any way. What you’re experiencing appears to be a bug in the Calculix adapter where preCICE is being fed a 0 time step because the adapter is wrongly thinking it’s already at 5.0 seconds and that’s when the simulation should end – so it tells preCICE that the Calculix time step should be 0.0 s. The work-around may be to set lines 21291 and 21292 in your new_flap_3d_1.inp file to:

*Dynamic, Direct
0.0001, 6

or at least greater than or equal to 5.0001.

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Thank you for your help. I understand now！

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