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FSI Module for blood vessel simulation

Posted Feb 27, 2014, 10:39 a.m. EST Studies & Solvers Version 4.4 3 Replies

Alexandra Diem
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Hi,

I'm trying to implement a very basic 2D axisymmetric model of a blood vessel (straight tube) using the FSI module as I'm interested in getting a wall deformation profile. The problem is that my model always fails with the following error:

"Failed to find consistent initial values.
Segregated group 2

Attempt to evaluate real square root of negative number."

I have tried finer meshes and get the same error message. My suspicion is that the BC are not correct. For example I am unsure as to how I should define the Boundary Load on the FSI Boundary. At the inlet I would really only like to specify the pressure using the piecewise function that creates a pressure pulse.

Would someone with more experience with the FSI module be able to help me?

Thank you
Alexandra

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3 Replies Last Post Mar 12, 2015, 5:39 p.m. EDT
COMSOL Moderator

Hello Alexandra Diem

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Jonathan Erbelding
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Posted: 1 decade ago Apr 24, 2014, 12:21 p.m. EDT
Were you able to find a fix for this? I'm literally working on the same problem and get the same error every time lol.
Were you able to find a fix for this? I'm literally working on the same problem and get the same error every time lol.
Siwei Bai
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Posted: 10 years ago Mar 9, 2015, 6:42 a.m. EDT
Have you solved your problem? I am working on a similar model and facing similar situation atm :(
I also had similar errors at the beginning but then I changed the initial conditions and I now have a different error msg....
Have you solved your problem? I am working on a similar model and facing similar situation atm :( I also had similar errors at the beginning but then I changed the initial conditions and I now have a different error msg....
Nagi Elabbasi Facebook Reality Labs
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Posted: 10 years ago Mar 12, 2015, 5:39 p.m. EDT
You need a boundary condition at the bottom of the fluid domain. If for example you assign the bottom boundary to the “Open Boundary 1” node the model works for a little then fails to converge, so there is something else wrong. Also there is nothing fixing the blood vessel displacement in the vertical direction.

Nagi Elabbasi
Veryst Engineering
You need a boundary condition at the bottom of the fluid domain. If for example you assign the bottom boundary to the “Open Boundary 1” node the model works for a little then fails to converge, so there is something else wrong. Also there is nothing fixing the blood vessel displacement in the vertical direction. Nagi Elabbasi Veryst Engineering

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