The movement of particles and their positions in Periodic cell

Asked by hjz on 2020-06-12

Hi everyone,
     I am using the periodic boundary in YADE to simulate a plane strain compression test. After the shear loading, I export the information of particles and find that the domain occupied by particles is not rectangular any more. As shown in Figure:
https://i.loli.net/2020/06/12/cELi7vZIMVbt81k.png
the sample is distorted into a wave-like block. It likes that the particles move out the periodic domain. So, I am wondering how the particles move and their positions are recorded in the periodic cell.
Best regards,
hjz

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hjz
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2020-06-15
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2020-06-15
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2020-06-12
Jan Stránský (honzik) said : #1

Hello,

particles are free to move arbitrarily, regardless dimension of the periodic cell.
Just for the contact detection phase (and Yade GUI display), the positions are **virtually** wrapped into the cell (+- one period).

If instead of true particle position you want the wrapped positions, use [1] and export O.cell.wrap(b.state.pos) instead of b.state.pos (or do it in the post-processing phase).
Both approaches (true and wrapped position) are reasonable and have their use cases.

cheers
Jan

[1] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Cell.wrap

hjz (1341132388-4) said : #2

Thanks, Jan