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CFX mesh deformation of fine elements

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Old   January 29, 2008, 17:31
Default CFX mesh deformation of fine elements
  #1
Ji Ke
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Hi, I am doing a CFD analysis on a scroll compressor for my thesis project.

here is a good animation of what I am trying to simulate:

http://cryo.kaist.ac.kr/images/scroll_cw.gif

I am using mesh deformation, but the problem is that I have very large features (10mm) and very small features (0.02mm) deforming at the same rate, and as you can see from the animation, I have a wall that is static (blue scroll) and a wall (red scroll) that is in motion.

So what happen is that after deformation, the mesh will end up being so stretched that CFX returns a negative volume error. If it does not, I don't think a solution with this kind of stretching is accurate.

Can someone give me some advice on how to solve this kind of problem?

Thank you in advance.

Ji
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Old   January 29, 2008, 19:18
Default Re: CFX mesh deformation of fine elements
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Glenn Horrocks
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Hi,

This form of motion will be very difficult to run in CFX. Your best bet is to do a good quality (preferably hexa) mesh and carefully adjust the mesh smoothing to avoid negative volume elements.

Glenn Horrocks
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Old   January 30, 2008, 04:38
Default Re: CFX mesh deformation of fine elements
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Andreas
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We did a lot of srew compressors and gear pumps, and the only chance in simulating so large displacements with changing gap sizes is to generate a lot of topological identical meshes for one revolution and let CFX read them in on runtime as is described in tutorial 20.
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