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Re: [Question #703104]: Changing the periodic cell for cylindrical samples

 

Question #703104 on Yade changed:
https://answers.launchpad.net/yade/+question/703104

Jan Stránský posted a new comment:
> Here, I still need periodic boundaries to allow for the exit/entry unless there is a method to avoid YADE periodic boundaries at all (no boundaries where particles themselves provide the stability or facet boundaries with occasional contact activation/deactivation--- just brainstorming).
> As you mentioned earlier, boundaries are the issue and I am trying to figure out when the rotation (position, velocity, force) should take place or even if I need to generate new particles exactly at my desired location with the velocities and forces of the exiting particles to provide a smooth granular flow. 

In the existing implementation, I like the approach that the particle can have arbitrary position, but is treated as if it would be "wrapped" inside the periodic cell (and its periodic images being around).
This way, you do not need to delete/create particles, just take into account that in reality the particle is outside, virtually meaning that it would be "on the other side".

> In the latter, I remove the particles which fully exit the boundary
which causes a temporary stop of the run (why is that?).

I have no idea :-)
Maybe some internal computation / processing due to deleted particles, in consequence deleted interactions ...
Impossible to say just from such description..

> Also, is there a way to disable the particle (and image) generation in
the opposite boundary? I do not need two of the four periodic
boundaries.

No (not in current implementation).
You can workaround it by enlarging the periodic cell, practically not using the periodicity in one direction, but from computation point of view, the simulation is still fully periodic.

Resume: forget existing periodic boundary conditions (periodic contact detection) for your use case, it is not usable.
You can get inspiration (e.g. the no delete/create approach), but you cannot directly use the code.

Cheers
Jan

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