lammps Granular package

Dear all,

I’m trying to simulate a granular system with lammps, but I have some problems plz help me, if it’s possible.

In my system I need to have Gaussian distribution for diameters of spherical granular particles between a and b, so I use read_data command. As I use this command in both of fixed diameter and Gaussian distribution, I get very different results from same script which uses create_atom command (fixed diameter)
1- Is there any command to set random diameter for spheres with Gaussian distribution?
2- Is there any bug with read_data command?

Suppose granular spheres are in a fluid, so they will feel Archimedes Force,
1- Is there any way to use this force?

Best regards,

You’re saying that a simulation with monodisperse particles

gives a different result than one with a Gaussian distribution of diameters.

Why wouldn’t that be the case?

You can use the set command to set the diameter of each particle

and use a variable that invokes the variable normal() function to
sample a Guassian distribution. I’'ve never done that, but I think

it should work. I suggest you do a immedate dump or write_data

command after using set to see if the diameters are what you expect.

There is a gravity fix that is often used with granular particles, see

its doc page. Whether that is similar to an Archimedes force, I don’t know.

If you want to couple granular particles to a fluid, look into he LIGGGHTS

package linked to here: