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Deformed Mesh in DFBI

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Old   March 15, 2021, 12:48
Default Deformed Mesh in DFBI
Will Crawford-Jones
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I'm trying to model a sphere rolling over some other spheres in open channel flow (see attached image "Geometry_Scene_1_image_1.500000e-03.png"). I have set up a DFBI model- under [tools < motions] I have included DFBI Rotation and Translation (which enables 6 DOF movement of a body) and DFBI Morphing (which I understand is for the morphing of the mesh). I have set up a contact coupling such that the sphere does not 'move into' the lower spheres and cause an error.

Firstly, I ran the simulation and noticed that the cells did not seem to get refined and between the moving sphere and the left base sphere became stretched (see attached image "Geometry_Scene_1_image_2.000000e-03.png"- they progressively became more stretched than this). Anyway, I eventually encountered a negative cell volume error.

I then explored the Adaptive Mesh feature and set Adaptation Requests to various mesh metrics (cell quality, aspect ratio etc). However, the cells continue to stretched and I encounter a negative cell volume error even quicker than before.

My question is: how do I set up an adaptive mesh for my case of a translating and rotating sphere; as the sphere moves away from the bottom left sphere I would need new cells to be created rather than stretched. Also, I would need the cells downstream to be removed as they become compressed. At the moment, cells are stretching and I am getting negative cell volume errors as well.

Thanks a lot

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File Type: png Geometry_Scene_1_image_2.000000e-03.png (136.2 KB, 12 views)
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Old   March 18, 2021, 04:54
Will Crawford-Jones
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Anyone have any ideas with this please? Any help you can give would be great

Thank you!
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6 dof, dfbi morphing, open channel flow

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