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Sloshing Tank with FSI
Posted 18 feb 2013, 05:44 GMT-5 Version 4.3a 5 Replies
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I calculate the waves of a water tank and then damp with a structure the waves. At the beginning I start with a single excitation an then wait and just let the gravity do the job. My model is similar to the sloshing tank example but rebuild with the FSI. I added then a bar which is made of rubber with a damping loss factor.
Now the problem: When the young modulus is 10e9 the model works fine, but the bar moves only for um. When I reduce the young modulus to 1e9, the model didn't converge. Does anybody know how I can make this model more robust? I would like to see the bar swinging within the waves and set the damping factor an the size of the bar to optimally damp the waves.
My model is attached.
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I'm not by my WS so I cannot check your model, one thing I suspect is that you get harmonic coupling, by lowering the Younf modulus you get lower eigenfrequencies and the fluid structure might interact heavily, givening issues t the solver for the convergence.
One way to reduce the ringing is to turn OFF the include inertial terms, which drops the 2nd derivative of the time or frequency dependent euations, this helps the covergence, but any oscillatory property is also suppressed, so the model is less representative. But to start with and to improve the convergence, it's often usefull, once it runs OK you can try to turn it on again (perhaps by lowering the time steps, or using a intermediate or strict time stepping, better coupled to the highest oscillatory frequency observed
FSI s complex physics and is far from trivial, it requires some tests and runs, not to say careful validation to verify the results
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Good luck
Ivar
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In the fluid-structure-interface, when I enable the "advanced physics option", I can activate for walls "use weak constraints" but for the "prescribed mesh velocity" I can't choose this option. In the example sloshing tank which uses Moving Mesh (ALE) I CAN choose this option. I'm wondering because also FSI uses ALE.
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unfortunately, I cannot really answer that one, but there must be someone else out here knowing that in detail ;)
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Good luck
Ivar
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same problem occuring in my module also.
When I am dealing the sloshing_tank model ,rebuild with fsi , I cann't choose normal velocity at free surface and thats why free surface movement does not showing.
If you resolved it, then please post here.