Generate open (low-density) packing

Submitted by tapsab on Wed, 09/19/2012 - 17:38

Hi,
I want to run a simulation of compaction of an open (low-density) packing. To save time I am confining my simulation to 2D by using a thin periodic slice. Any ideas on how to generate an open packing (say with a packing fraction of ~ 0.4) in this situation that is mechanically stable under gravitational load? If I just generate particles using insert/pack and let the particles settle under gravity they tend to crystallize and I obtain a rather dense packing.

Any suggestions would be appreciated,
Thanks,
Tapan

Forums:

cstoltz | Wed, 09/19/2012 - 21:37

I would guess that if you add sufficient cohesion, you would be able to create a reasonably open packing, at least when viewed macroscopically. Microscopically, I'm not so sure. Would have to play a bit with the CED to try to tune to a desired volume fraction.

Regards,
Chris

tapsab | Wed, 09/19/2012 - 22:51

Chris,
Thanks for the tip. That's the first thing i tried too, playing around with cohesion, unfortunately I needed to make the particles very sticky (large CED) to get an open packing and that amount of cohesion plays a big role in the subsequent compaction response which is undesirable. My simulation is of a material like milk powder or talcum powder which when poured into a container gives a really low-density, "fluffy" packing. It might be that a 2D packing inherently leads to a dense state so I will have to just bite the bullet and go with a 3D packing with an appropriate particle size distribution and cohesion to get the open packing.

Best,
Tapan