Learning Forum

[biocfd]

Hey there,

currently I'm running a 1-way FSI simulation using Fluent and Structural in the Workbench. Displacements get transferred from Structural to Fluent.

My setup is basically a heart valve which is immersed into a cylindrical fluid domain (blood). I want to investigate the influence of the heart valve on the flow field.

[Rahul Kumar]

Hello,
You mentioned that there are a lot of orphan cells, did you try the boundary distance based method?

[biocfd]

Hey thanks for putting some thoughts into my problem. I tried both boundary distance and volume based methods already. The former turned out to give a slightly better overset interface. What I have also tried:

Different boundary types for the faces at the interface/overlap between the two component bodies
Different grid priorities, manual cut-controls and specific definition of overlapping boundaries
Modified donor search and modified hole cutting parameters

Especially specifying overlapping and non-overlapping boundaries improved the overset interface quite a lot, but didn't remove all the orphan cells. As you can see in the figures below, I'm still left with orphan cells all around the overlapping region (marked in red). Like this, the setup is pretty unstable and diverges after a few iterations.

[FranXAus]

Hi, Im doing a similar problem, did you manage to do this simulation successfully?

[biocfd]

Unfortunately not really.. From my understanding rn the problem is that the overlapping surfaces of the two component bodies have opposing surface normals. The support told me, that this is not allowed and this is what causes the orphans.

I tried to set up the problem without this "interface-like" boundary in between and I tried to use a collar mesh around this area, but both without much success. So for now I'm trying to just simulate with the orphans and hope that it's still converging properly.

What are your experiences with your case rn?