Problems while validating Turek and Hron (2006) FSI2 and FSI3 problems in solids4Foam
 

I have currently started working on FSI problems using your solids4Foam toolkit in foam-extend 4.0. While validating the Turek and Hron FSI problem from the tutorial, I am facing few problems as follows:

1. First of all, in the Turek and Hron paper, they have used "Saint Venant–Kirchhoff" material instead of "Neo-Hookean solid" material. Thus I have changed the material in simulation.

2. While validating FSI2, after every try with different materials (linear elastic, Saint Venant–Kirchhoff and Neo-Hookean solid), different FSI interface schemes (fixedRelaxation, Aitken and IQNILS) and different linear and non-linear solid models, the simulation is diverging between 7-8 sec with the following FOAM error.

--> FOAM Warning :
From function void neoHookeanElastic::correct(surfaceSymmTensorField& sigma)
in file materialModels/mechanicalModel/mechanicalLaws/mechanicalLaw/mechanicalLaw.C at line 549
Material linearity enforced for stability!

3. While validating FSI3 with Neo-Hookean solid, simulation is not diverging but results are not matching properly with Turek and Hron paper. WIth Saint Venant–Kirchhoff model, simulating is not converging even after 15sec. Amplitude or displacement (dx and dy) gradually reducing.

4. I have also tried with two different Meshes and reduced the under relaxation factors for D,DD, DEqn, DDEqn but facing the same problem.

Can anyone help me out with this problem ?