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FSI problem of improper constraint

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Old   March 18, 2013, 03:45
Default FSI problem of improper constraint
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Dr. Moloy Kumar Banerjee
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Dear all,
I am trying to simulate the FSI problem where, a fluid is flowing through a pipe of dia 2cm and length 8cm. My aim is to check the behavior of the wall material under the influence of fluid flow and vice-verse. For this simulation I select the Youngs modulus for the pipe material as 10Mpa, and poissons ratio as 0.3 and density of 1050 kg/m3. For the fluid model I have selected the density as 1050kg/m3 and the viscosity as 0.003 Pas.
For fluid domain BC, I used transient pressure at inlet and zero gauge pressure at outlet.
For the structural domain I select the front faces of the wall as stationary(as shown in figure) and the two surface that in contact with the fluid domain as fluid-solid-interaction BC.
My aim is to do the 2D analysis of the problem and hence I choose 2-3 element thickness of the entire geometry in the z-direction. Both the front and Back end of the fluid domain are given the symmetry BC.
Once I start the simulation using system coupling it shows the error " improper constraint in the structural system, which results in a very high displacement Uy=10^33 and finally it stops"

Is there any correction needed in the constraint definition. Please help me to rectify the problem..
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File Type: jpg fluid.JPG (48.1 KB, 7 views)
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Old   March 19, 2013, 07:13
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any help is highly appreciated
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Old   March 25, 2013, 14:23
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Given the low Youngs modulus it's likely unstable coupling. "Solution stabilization" in version 14.5 would address this. If you can download the Fluent FSI training material from the ANSYS Customer Portal there's a whole chapter on convergence that covers this.
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Old   April 4, 2013, 03:47
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Is there any download link for Fluent FSI training? I could not access the Ansys Portal.
Thank you.
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