# A case of rigid motion combined with deformation (OpenFOAM-Calculix FSI)

Hi all,

I am making a case to analysis deformable plate with rigid motion. It is adapted from `/tutorials/FSI/cylinderFlap/OpenFOAM-CalculiX`. I change the boundary of Nfix1 in `./OpenFOAM-CalculiX/Solid/flap.inp` and add the rigid motion in it like this:

*BOUNDARY
Nfix1, 1, 1
Nfix1, 3, 6
*BOUNDARY,AMPLITUDE,FREQUENCY
Nfix1, 2, 2, 0.001, 0.1
*BOUNDARY
Nall, 3, 3, 0
Nall, 4, 4, 0
Nall, 5, 5, 0
Nsurface, 1, 0.0
Nsurface, 2, 0.0
Nsurface, 3, 0.0

/tutorials/FSI/cylinderFlap/OpenFOAM-CalculiX:

My case:

However, i can not run `./Allrun` appropriately(centos7.8, OpenFOAM5.x, CalculiX2.16). The case stop at 0.002s, so i have to shut it down by press “c” in command window. Here are my log files:
Fluid.log (1.1 MB)
Solid.log (92.3 KB)
precice-Calculix-convergence.log (1.4 KB)
precice-Calculix-iterations.log (126 Bytes)

This is my case file:
OpenFOAM-CalculiX.tar.gz.txt (20.3 KB) (remember delete the .txt)

How can i realize the stimulation of rigid motion combined with deformation? Is my idea of adaptation correct?

Thank you.

Your simulation stops because CalculiX diverges. Technically everything works. It’s a numerical problem.

To better understand your case, a few questions:

• What exactly do you mean by “rigid body motion” here?
• Where is the structure deformation fixed?
• Do you start from a converged fluid solution?
• What exactly do you mean by “rigid body motion” here?

‘Rigid body motion’ means that the left end of this plate is active sinusoidal oscillation, not fixed.

• Where is the structure deformation fixed?

The left end of this plate is fixed like this:
*BOUNDARY
Nfix1, 1, 1
Nfix1, 3, 6
*BOUNDARY,AMPLITUDE,FREQUENCY
Nfix1, 2, 2, 0.001, 0.1

Its y-translation is set to sinusoidal oscillation.