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Old   October 12, 2007, 17:42
Default dynamic mesh bondary layer cells
  #1
geri
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Dear experts,

I am trying to analize the rigid body moving capabilities in fluent in case of bridge deck section flutter assassement. I applie a boundary layer mesh and I want this region move with the rigid body and not to deform or change. Can it be achieved???

Thanks
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Old   October 13, 2007, 21:41
Default Re: dynamic mesh bondary layer cells
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Giles
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Make the spring constant in the DM smoothing settings 0, so the movement is spread as globally as possible. In addition if possible make the UDF move the deforming surface 10% of what you need it to move, then perform 10 mesh updates with it, so each step is small. This worked for me, hope it works for you.
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Old   October 14, 2007, 07:26
Default Re: dynamic mesh bondary layer cells
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geri
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Dear Giles!

Thanks for Your answer, the zero value of the spring factor solves the problem, the boundary cells move beautifully with the rigid body. I just don't understand what You mean the 10%!!! (My UDF is the simples as it can be, it defines a prescribed motion of a body).

Many thanks,

Geri
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Old   October 16, 2007, 07:16
Default Re: dynamic mesh bondary layer cells
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Amr
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Hi, If you have already a simple UDF (compiled ofcourse), then you can assign the UDF to both the body as well as the boundary layer. This would give the exact prescribed motion to the cernters of gravity of both.

To do so, you may want to have a look on the 6DOF UDF made on the fluent users website (need to have an access) and make use of the "calls" and "Num_Calls" variables. This is just for calling the function twice before writing the new locations on centers of gravity, thus enabling motion for both of your Blayer and the body itself.

If you find this difficult, you can still live with the low spring constant afterall.

Amr
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Old   October 16, 2007, 09:47
Default Re: dynamic mesh bondary layer cells
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Geri
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Dear Amr,

This solution seems to be the best, i will try it.

Many thanks
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