[PhiSch]

Hello,

i am trying to simulate the blood flow through an aortic valve with a 2-way-fsi configuration (fluent / system coupling).

It should start with a pulsatile flow through a pipe, which widens due to the pressure on the wall caused by the blood flow. This works fine, until I get a 'negative volume error'.

The reason is, that the inner nodes of the outlet boundary are not moving with the rest of the deforming mesh since the pipe contracts based on the pressure related widening.

Undeformed:

Deformed:

Left undeformed, right deformed:


Only the interface nodes are deformed via the system coupling option. The outlet is declared as 'deforming --> faceted'.
Overall the options 'diffusion based smoothing' and 'remeshing' are activated.

How can I get the inner nodes move along with the interface nodes in one "plane"?
Do I have to wirte a UDF which takes the position of the edge nodes and transforms the inner nodes in a moving plane and declare the outlet as 'deforming --> plane'?

I've tried different parameters (diffusion, spring-based) within the dynamic mesh properties which took no effect.
The outlet still behaves like a stationary mesh.

Best regards
Philipp