LIGGGHTS® - User Forum

Dear all,

i want to evaluate the number of contacts of a group of particles with themselves. Basically i want to know if a group of particles stays "intact" all the time or gets "fractured" over time. For this i found the interesting compute "group/group" command. Unfortunatly when i use the command i get the error message:

"Pair style does not support compute group/group"

In the documentation it says there are no restrictions to this compute, so i'm curious what the reason can be. I'm using the pair_style gran model hertz ...

Hi Everyone,
I am a newbie using LIGGGHTS. My problem would be similar to a steady state flow of spherical particles through a hopper domain with conical bottom, so I took it as a start. I have been able to run a simulation where I inserted the particles, and let them fall under gravity (picture attached)
However, I have not been able to run it in a "Recirculation" mode where the particles leaving the domain would be reinserted from the top. Can any body help me out with a means to do that.

My issue is that I have ran three different codes keeping everything same but only these 3 commands different in each code

fix gravi all gravity 9.81 vector 0. 0.0 -1.0.
fix p all addforce 0 0 -9.81
fix p all setforce 0 0 -9.81

So, the code with gravity force command acts like the particle comes down very slowly but in their 2 commands i.e. (add-force and setforce) the particles leaves the box quiet early, My question is that in all three cases the particles should act similarly as the force is same in three cases? Is the issue seems to be in fix?

Hello,
I am just starting to look into simulation with liggghts for my studies.

Is there any way to output the distribution of CPU cores in space and is it possible to change the number of CPU cores after startup?
As an example I want 4 cores for filling and 16 for further steps like mixing.

thanks for your help

Phil

Does anyone install LIGGGHTS successfully on a mac with M1 (apple silicon)? I could not as VTK-8.2 could not be installed. Thanks.

Hello guys, apologies if the question is repeated here.
I have been trying to simulate two types of particles through inclined surface. I don't want to use `.stl` file to define surface for particles insertion points.

I want to use cylindrical region and insert particles from that region.

When I use the `insert.stl` then it works but when I remove insertion cad and use region with

`fix ins nve_group insert/rate/region seed 32452867 distributiontemplate pdd1 &`

It gives error.

I am using the units microns and
atom_style sphere n
neighbor 0.002 bin
neigh_modify delay 0

with the configuration of the data file below
5 atoms
0 bonds
1 atom types
0 bond types

-0.1 0.1 xlo xhi
-0.1 0.1 ylo yhi
0 0.1 zlo zhi

Atoms # full atom id atom type diameter density xyz(for sphere)

I am trying to fill the spherical particles inside the cubic bed. I have created the geometry using the blender. But no matter how refined the mesh I am creating liggghts is showing mesh error like curvature aspect ratio etc. I see tutorial examples of liggghts, it seems mesh should not be a big issue, but why I am getting this error? Another question is in my mind that whether the blender is good software for creating geometry for DEM purposes?
Which software is more suitable for stl or obj file
Thanks in advance

Hello Community