Random packing of granular spheres

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1

Dear LAMMPS users,

I am working on a granular system and using the fix pour command to settle the particles under gravity.

fix 3 all pour 4000 1 29494 vol 0.2 100 region fill diam one 5e-6 dens 2500 2500

The dimensions of the simulation box: xyz = (5e-5)(5e-5)(2.5e-3) = 6.25e-12

My issue is that the particle insertions were less than asked for, 1361 instead of 4000. From visualization, I can see that the particles are not so densely arranged initially. Manual calculations for an initial volume fraction of 0.2 for the specified dimensions would mean atleast 95000 particles could be inserted.

Is this dependent on the number of attempts or am I missing something here. Please guide me.

P.S : SI units used above.

Best regards,

Sandesh Kamath,
M.Sc.

Universität zu Köln
Institut für Geophysik und Meteorologie
Raum 3.110
Pohligstr. 3, 50969 Köln, Germany

Tel: +49 (0)221 470-3691

2

Dear LAMMPS users,

I am working on a granular system and using the *fix pour* command to
settle the particles under gravity.

*fix* 3 all pour *4000* 1 29494 *vol 0.2* 100
region fill diam one 5e-6 dens 2500 2500

The dimensions of the simulation box: x*y*z = (5e-5)*(5e-5)*(2.5e-3) =
6.25e-12

My issue is that the particle insertions were less than asked for, 1361
instead of 4000. From visualization, I can see that the particles are not
so densely arranged initially. Manual calculations for an initial volume
fraction of 0.2 for the specified dimensions would mean atleast 95000
particles could be inserted.

Is this dependent on the number of attempts or am I missing something
here. Please guide me.

​there is not enough information here to provide meaningful advice. most
likely there is some conceptual problem.

axel.​