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Re: Periodic Boundary Conditions in DEM



This is very interesting. I've thought to that many times.
Did you look how the SAPcollider works? This is probably where part of 
the solution is.
I would implement periodic boundaries by creating/deleting "ghost" 
spheres each time an original sphere is flagged/unflagged. In this case, 
the collider will detect the contacts between opposite sides as contacts 
between an original sphere and a ghost one. The ghost spheres should be 
of a different class, so that engines like 
InteractionGeometryDispatcher, PhysicalActionApplier,... will handle 
them differently. Inside those classes, it will be possible to add the 
resultant force on the ghost to the resultant force on the original one, 
to impose that the movement of the ghost is the same as the movement of 
the original sphere, etc.

Perhaps the member data of ghost spheres should be made of a lot of 
references to member data of the original (resultant force, velocity,...).

This is how i would try to do it, not sure it's the best way however...

I would recommend waiting for the comments of Janeck :).


Chareyre Bruno
Maître de conférence

Institut National Polytechnique de Grenoble
Laboratoire 3S (Soils Solids Structures) - bureau I08
BP 53 - 38041, Grenoble cedex 9 - France     
Tél :

Kenneth Ball a écrit :

>Hi, I'm trying to implement a periodic boundary condition in the DEM
>module for a couette model I'm working on.
>Basically, I need YADE to flag any spheres whose bounding volume has
>crossed some threshold and have that sphere interact with both the spheres
>behind it and the spheres on the opposite side of the volume.  Then I need
>YADE to identify spheres whose positions have crossed the threshold, and
>move them back to the opposite side of the volume.
>Has anybody implemented something similar in the past?  I'm fairly new to
>the YADE software, so any advice would be very helpful.
>Kenneth Ball
>North Carolina State University
>Yade-users mailing list

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