External BC

[Nicolas Bernard]

Hello everyone,

I'm currently working on "tube collapse" using svFSI, and I have a question regarding the possibility of setting external boundary conditions such as an external pressure that induces the collapse of the cylinder. I've noticed that it's possible to apply boundary conditions to the walls of the cylinder, but I'm wondering if these conditions are solely associated with the fluid.

Any insights or guidance on this matter would be greatly appreciated.

Thank you!

[David Parker]

Hello,

Maybe you can use a Neumann BC, try it and and see.

Cheers,
Dave

[Nicolas Bernard]

Hi David,

I've been attempting to recreate an exterior pressure using a Neumann-type boundary condition as you said, but it doesn't seem to be functioning as expected. No matter what I try, the displacement consistently occurs outwardly. I even experimented with changing the sign of the condition, but it doesn't seem to have any effect.
As a potential workaround, I thought about employing two coaxial cylinders, where the inner cylinder would be influenced by the deformation of the exterior one. However, I keep receiving an error message stating "there are too many regions in here." during mesh generation. This has left me wondering about the maximum number of surfaces a model can have. Understanding this limit could help me determine if the issue lies with my approach or if it's related to the exported file.

Thank you for your time.

[David Parker]

Hello,

SV mesh generation will not work with coaxial cylinders, does not understand interior/exterior faces I think.

Have a look at the examples in https://github.com/SimVascular/svFSI-Tests and the description of the commands in https://github.com/SimVascular/svFSI/bl ... master.inp.

Cheers,
Dave