svFSI convergence problem for HGO model

[marisa bazzi]

Hey all,

I have been trying to use the HGO model in my FSI simulations, however, I cant make it work. It runs for 1-2 cardiac cycles and then blows up. When I check the solution, it always blows up for the wall stress. I tried different things, with and without prestress, reducing the time step (the last one I used was 1e-5), using rigid wall results as initial input, I also played around with the HGO parameters to reduce the exponential profile of it. Nothing worked.

So the last thing I tried was to set the parameters that define the exponential behavior to be close to zero, therefore the model should be a neo-Hookean-like behavior (I've never had any problems with the neo-Hookean model). However, it is still didn't work. So I am wondering if it could be a bug in the HGO model, or there is something I am missing it doing wrong when using the HGO model?
Domain: 1 {
Equation: ustruct
Constitutive model: HGO {
a4: 1e-10
b4: 1e-10
a6: 1e-10
b6: 1e-10
kappa: 0
}

Density: 1
Elasticity modulus:4.43e7
Poisson ratio: 0.4
I included my input files and results in the folder https://drive.google.com/drive/folders/ ... sp=sharing.

Thanks so much
Marisa