FSI with CalculiX and OpenFOAM: Preload and pre-deformation of solid

Dear all,

I am performing FSI simulations with OpenFOAM and CalculiX. In particular, I am trying to set up a case with a pre-deformed solid, which is subjected to a preload . My idea was:

  1. Dynamic CalculiX simulation to deform the solid
  2. Export deformed solid shape to .stl, create fluid mesh which fits the deformed interface
  3. Start the FSI simulation
    → CalculiX: Use initial (undeformed) geometry file, initialize with the deformation and tension results from step 1

In his master’s thesis [1], @KyleDavisSA used the restart-option in CalculiX. He stopped the FSI simulation, exported the deformed CalculiX mesh to .stl and built a new OpenFOAM mesh with the new geometry, using the solid deformation and the mapped flow field as initial conditions for the new simulation. This worked well and it is similar to what I want.

However, I feel like my approach might be fundamentally wrong. The way I understand it, CalculiX receives the force at the interface from OpenFOAM in the coupling step. This might be the source of the problem, maybe the internal tension state of the solid is “incompatible” with the pressure coming from the fluid?

This question is more on a theoretical level, but I can supply some files if anyone thinks it should work.
I’m using CalculiX 2.16, OpenFOAMv2012 and preCICE-2.2.1.

[1] K. Davis, “Numerical and experimental investigation of the hemodynamics of an artificial heart valve”, Stellenbosch University, 2018. Numerical and experimental investigation of the hemodynamics of an artificial heart valve.