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Old   September 10, 2007, 11:56
Default Transient Model, Varying Mesh files...
  #1
Erich
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Hello,

Is the only way to change mesh files in a transient run through the use of a Junction Box Routine?

Thanks for your input.

Erich
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Old   September 10, 2007, 12:41
Default Re: Transient Model, Varying Mesh files...------We
  #2
CycLone
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Yes, but this can only be done if the mesh topology remains the same. If you want to run a transient where there is remeshing being done you will have to stop and restart the solver between meshes. This can usually be limited to a few key-meshes in a run, with mesh morphing handling the boundary motion in-between.

-CycLone
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Old   September 10, 2007, 14:44
Default Re: Transient Model, Varying Mesh files...------We
  #3
Erich
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Thanks CycLone,

To what level will the mesh morphing usually go? Is this morphing defined only by mesh motion?
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Old   September 10, 2007, 16:51
Default Re: Transient Model, Varying Mesh files...------We
  #4
JH
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CycLone means that you cannot change the initial mesh, just carefully move their nodes without degenerate the volumes that they conform. (for example: overlap two or more nodes)
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Old   September 10, 2007, 16:53
Default Re: Transient Model, Varying Mesh files...
  #5
CycLone
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The mesh morphing can be pushed pretty far, but it will depend on what it is your doing. Motion can be defined at a boundary or expressions can be provided for the volume motion. The solver "diffuses" the motion through the rest of the mesh by solve a mesh diffusion equation, as opposed to using a spring analogy.

In general it can't handle the complete collapse of a portion of the mesh (i.e. a valve closing), but you could get close. In some cases you can also modify the geometry slightly, such as adding a small "seat" for the valve mesh to collapse into, and add sliding interface along the side so only the moving portion needs to be compressed.

-CycLone
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Old   September 10, 2007, 23:03
Default Re: Transient Model, Varying Mesh files...------We
  #6
johnny
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One of the tutorials covers reading in different meshes through a junction box routine. I think # 20 or 21.
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Old   September 11, 2007, 09:19
Default Re: Transient Model, Varying Mesh files...------We
  #7
Erich
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Thanks for all of your contributions. I have gone through the tutorials. The problem we have will need the topology to change and the mesh deformation would be quite severe. I am leaning towards an approximation per CycLone to produce a 'design' cycle CFD model to look at the big picture.

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Old   September 11, 2007, 10:15
Default Re: Transient Model, Varying Mesh files...------We
  #8
johnny
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If the mesh cannot be mapped, then you cannot use a Junction Box routine. You will need to stop your run, and interpolate the results on to your new mesh.
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