fix insert achieved volume fraction depending on particle size?

Submitted by PaulWinkler on Wed, 08/07/2013 - 10:40


I am inserting particles via fix insert/pack in a region using volumefraction_region to specify the amount of particles inserted. I understand the volume fraction as percentage of volume, which is covered by particles. But if I compare the given volume fraction and the reached particles volume, there is a linear deviation. For large particles (diameter equal 1/10 of width/height/depth of volume) there is only 50% of the aimed volume fraction (0,1 – 0,5) reached. There is no Warning, all particles are inserted. For smaller particles (diameter 1/100 of w/h/d of volume) the deviation between volumefraction_region and the actual percentage of covered volume is getting smaller.

For example:

d=1/10 * x
given volume fraction: 0.5
reached volume coverage: 0.255
deviation: ~0.5

d=1/100 * x
given volume fraction: 0.5
reached volume coverage: 0.47
deviation: ~0.94

Has anybody an idea what could be the reason?


Edit: add values for deviation