XANSYS Message: 93037 [Go back to message list]
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Subject: Re: Ansys FSI nightmare
Author: Y Y Tan
Date: 2008-04-26 05:27:35Hi guys,
Just an update of what's going on. I have tried reducing the timestep of my
problem and the good news is everything went smoothly throughout the solution
process. However, the bad news is that the solution could not converge within
the maximum stagger iterations set which is 20 iterations. Anyway I will try
increasing the iterations and see if it works out okay but I kinda doubt that
because throughout the solution, the tube seems to be moving all over the
place. At the start say the first five stagger iterations, the tube buckles
exactly the way it should, then for the next five stagger iterations, the tube
buckels on the other axis, then for the next five iterations, the tube does not
buckle at all and finally the in the last five iterations, the tube buckles
back to the undesired axis. My guess would be it would just repeat itself. Do
you guys think that I might need to make any changes to my fluid timescale
control which is currently at auto timescale with a conservative length scale
option. Also, I did not set up any initialisation for my flow field, do you
think this matters?
Okay, so I looked at the results from my unconverged solution. I notice
something very weird, my fluid interface does not follow the solid interface,
although they move in the same direction but the solid interface moves much
more and goes through the fluid interface. Is there something wrong here or its
just because my solution hasn't converged? Does it happen because I set the
displacement received from the structural side to have an under-relaxation
factor of 0.1? *my FSI node interpolation from both sides match 100%*
Thank you guys, its morning now and I guess I would need some sleep. I hope to
hear from you guys. Goodnight.
Regards,
Tan Yi Yong
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