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DFBI for very high rotation?

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Old   May 26, 2012, 22:19
Default DFBI for very high rotation?
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muhsin
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Hi All
I have some difficulties in simulating rolling motion of a small barge in wave flume...
-- I am using fine mesh near free surface and body but since DFBI rotation and translation treats whole volume mesh as rigid body, after some time the free surface moves to coarse mesh region and gets distorted and looks like the free surface submerges the body.
-- I am able to get comparable results for angles > 10 degrees. but for higher angles like 25 or 30 degrees I am facing the above problem.
-- Can anyone suggest what other DFBI models can be used to accommodate for larger DFBI rotation angles for better results.
boundary conditions are same as for Boat in head sea tutorial.

thank you
muhsin
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Old   May 27, 2012, 03:58
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DFBI morphing should be capable of doing it, but morphing usually needs a lot of power and resources. Of course, depending on the mesh size, but the same mesh size needs more resources than the rotation and translation model. And further, you have to make sure, cells don't get too distorted, otherwise you need to remesh, adding additional overhead.

When you're using 7.02, you can use overset meshes, that would be my first choice. But you will need a fine mesh in the whole overlapping area, due to compatibility in cell sizes when the boat rolls, so most likely your mesh will not be smaller due to use of overset meshes.
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Old   May 28, 2012, 14:12
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Ryan Coe
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Not sure if it's been published in a paper, but this looks like a similar study that might be useful

http://www.outreach.psu.edu/programs...erson-eric.pdf
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Old   May 29, 2012, 05:05
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Thank you Abdul and Ryan. im trying to use morphing it seems to be working.
also the residuals seem to much better than DFBI rot n trans. lets see for larger roll hw it behaves.
Ryan i will also have a look into the link sent.
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Old   March 7, 2014, 05:51
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Arun Krishnan.L.H
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Dear Munshin,

Can you please re-post the link? It is not working now. I am having a problem with DFBI+morphing.

Thanks
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Arun
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