Urgent - Periodic boundary conditions in LIGGGHTS

Submitted by tuks123 on Tue, 11/24/2015 - 15:29

I am simulating particles rotated by an impeller in a cylindrical container (see sample image attached here). The impeller has two blades (180 degree apart) and is rotating at defined speed.

I am able to simulate complete model. But want to reduce time by simulating only sector of the cylinder, using periodic boundary conditions. Want to simulate a 90 degree sector with one of the two impeller blades inside this. Want to define P1 and P2 as periodic boundaries, as particles exiting P2 should re-enter P1. I know we can define cuboid/box faces as periodic but this is different. The periodic faces P1 and P2 are starting from same origin and are at 90 degree with each other.

Is it possible to do such periodic boundaries in LIGGGHTS?

Your help will be much appreciated.

Thanks and regards
Tuks

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aaigner's picture

aaigner | Tue, 11/24/2015 - 16:37

Hi Tuks,

If it is urgent, use the search function next time. This question was already asked . ;-)

Short answer ... no.

Long answer: It would be a very nice feature, but as you mentioned, the particles would not be mapped to the opposite boundary, but rather to the left or right neighbor (boundary). Thus all forces, velocities, ... must be rotated with the boundary and the whole communication between processors has to be changed.
Since the periodic boundary feature comes from LAMMPS and the whole communication infrastructure is implemented in the 'basement' of LAMMPS, this would require a mayor rewrite of many parts of the code. I am sorry, but that's not easy to implement.

Bests
Andreas

tuks123 | Thu, 11/26/2015 - 06:16

Hello Andreas,

Thanks for prompt great reply. This helps me in making decision. The post was urgent, as I needed to take decision on simulation timelines.

Hopefully, this feature comes in future.

Thanks and regards
Tuks