random dense packing with bidisperse particles in Yade

Hi Lei,

a workaround is to use the core of the function [1,2] (copy paste
approach), but change the sp.makeCloud command to create desired packing,
something like:
###########################
from yade import pack
sp = SpherePack()
r1,r2 = 1.0, 0.4
num1,num2 = 20,100
sp.makeCloud((0,0,0),(10,10,10),r1,num=num1)
sp.makeCloud((0,0,0),(10,10,10),r2,num=num2)
sp.toSimulation()
###########################

cheers
Jan

[1] https://github.com/yade/trunk/blob/master/py/pack/pack.py#L454
[2] https://github.com/yade/trunk/blob/master/py/pack/pack.py#L554

As a comment, what randomDensePack is limited to do, is to consider uniform particle size distribution around a mean radius value "rMean" (see "rRelFuzz" attribute of randomDensePack).
So, it's indeed not possible to use it for bidisperse packing, but it is not limited to monodisperse packings either.

As another comment, regarding Jan's suggestion #1, you may also use "psdCumm" and "psdSizes" attributes of makeCloud function to define a bidisperse packing calling only once makeCloud, instead of twice in #1
(do not know if one method is simpler than the other, though)

Jerome

Dear Jan and Jerome,

Thanks a lot for your suggestion. It seems if my goal is only to generate a loose bidisperse packing, then either way is fine. For example, something like

psdSizes, psdCumm = [0.05, 0.05, 0.07, 0.07], [0.0, 0.5, 0.5, 1.0]
sp=pack.SpherePack();
sp.makeCloud((0,0,0), (1,1,1), psdSizes=psdSizes, psdCumm=psdCumm, distributeMass=False)

can generate a loose packing for me. It is also possible to use Jan's suggestion to generate a loose packing. Then I may need to apply isotropic compression and rescaling to get a dense packing. Is it the right way to go?

Many thanks again,
Lei

Hi Lei,

> Is it the right way to go?

in my opinion it is :-)
cheers
Jan