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Mesh motion - Rolational velocity components

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Old   January 30, 2006, 05:09
Default Mesh motion - Rolational velocity components
  #1
Manoj Kumar
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Hi

Do we have the option of imposing rolational velocity components to a deforming mesh? I can find just x,y and z components in 'Edit Boundary>Mesh Motion' panel.

Thanks

Manoj
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Old   January 30, 2006, 17:58
Default Re: Mesh motion - Rolational velocity components
  #2
Glenn Horrocks
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Hi,

Yes, you can do that but if the motion is only rotational it is easier to define it as a rotating frame of reference.

Glenn Horrocks
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Old   January 31, 2006, 07:43
Default Re: Mesh motion - Rolational velocity components
  #3
KBanks
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Hi Manoj,

If the mesh deformation itself is rotational, then you will either have to define that motion with an expression or use the Fortran Junction Box routine. After wasting many, many hours trying to get it to work "the easy way", I ended up only being able to achieve my aim using the Fortran method. It is difficult to say what will work for you without more detail of exactly what it is you are attempting to do.
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Old   January 31, 2006, 07:55
Default Re: Mesh motion - Rolational velocity components
  #4
Manoj Kumar
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Hi

I am working on a problem where a block floats in water contained in a tank. Due to sloshing force the block translates and rotates. How do I go about? I tried using a CEL function but there I could find just the option of translational motion.

I have been working on fluent and have recently shifted to CFX.

Thanks and regards

Manoj
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Old   January 31, 2006, 18:31
Default Re: Mesh motion - Rolational velocity components
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Glenn Horrocks
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Hi,

In that case the motion is best modelled as a deforming grid. Don't worry about modelling the rotations separately.

The CEL function is where you enter the function to describe the motion of every node on the moving boundary surface. It is called translation as each node only has translation degrees of freedom, a node cannot rotate. To define a general motion including rotation you give the nodes on a surface different translations.

KBanks is right in saying it is tricky to get these functions working, but I suggest you keep at it as in this case it will probably be much easier to define the motion as a CEL function describing the motion of the boundaries rather than a fortran function where you have to describe the motion of every node in the domain.

I have done many deforming mesh simulations and have done all of them in CEL.

Regards, Glenn Horrocks
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Old   February 6, 2006, 11:05
Default Re: Mesh motion - Rolational velocity components
  #6
KBanks
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Have you done rotations Glenn? It doesn't work as far as I (and a very well qualified ANSYS support engineer) found to our cost, at least for my application. Linear movements are a breeze on the other hand.
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Old   February 6, 2006, 18:13
Default Re: Mesh motion - Rolational velocity components
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Glenn Horrocks
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Hi,

Most of my stuff has been purely translation, and usually any rotations are fairly small. I have never tried doing translations with large rotations.

Glenn Horrocks
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