Spatially activated fiber stress

[kko27]

Problem

User specified spatial fiber stress was previously implemented for conduit simulations in svFSI https://github.com/zinanhu0810/svFSI. I am planning to implement this for svMultiphysics.

Solution

Translate code from the GET_FIB_STRESS subroutine found in MATMODELS.f in this svFSI fork https://github.com/zinanhu0810/svFSI.

Additional context

Issue was previously created, but closed due to inactivity:https://github.com/SimVascular/svMultiPhysics/issues/74

Code of Conduct

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[kko27]

I'm starting to think that maybe working on strong electromechanical coupling might be a better idea, but will follow up on this soon

[dseyler]

@kko27 I was thinking it might also be useful to be able to specify spatially varying directional stress distributions. See 497. @aabrown100-git suggested that creating an ActiveStress class encoding activation time, magnitude, and directional distribution might be the best way to do this. Curious if you've previously worked on anything similar or have settled on the strong coupling route?

[kko27]

@dseyler I am now working on a stronger coupling approach where the electrophysiology state variables are fed into an active-tension model which provides the active stress to the PK stress tensor. That being said, it probably still makes a lot of sense to have spatially distributed active stress features (in situations where we don't want to simulate the coupled electromechanics).