LIGGGHTS® - User Forum

Hi,

I was wondering if we can convert the vtk files of granular particles to stl file or directly export the particle as stl (using dump). I only found that we can convert wall vtk to stl but would like to know if this is possible for particles as well.

Thank you.

Dear All,

I would like to compare the output of compute contact/atom for the contacts count of each particle/atom (to calculate the number of contacts for each atom in a group) and compute pair/gran/local for the number of pairwise interactions or particle-wall interactions in the system.

compute contact/atom
compute atomtrack all contact/atom
dump collide all custom 100 CSVs/dump*.doll.csv c_atomtrack

This question comes often. I wanted to answer it with a picture but pictures in replies are not allowed.

In short, use the calculator filter and calculate the magnitude of the force with its components.
THEN use the tube filter. You can scale the chains using the newly-calculated value

Hello everyone, I have made a small tutorial especially for Spanish speakers, any errors you find please let me know since I have been using liggghts for a short time.

Hola a todos, he realizado un pequeño tutorial en especial para las personas de habla hispana, cualquier error que encuentren porfavor haganmelo saber ya que llevo poco tiempo utilizando liggghts

Hi everyone!

Hi,

I am facing a problem about outputing the contact force of different particle groups. In my code, I first wrote:

1#: compute fc all pair/gran/local force id pos
2#: compute fcSparticle sparticle pair/gran/local force

where "sparticle" is a certain group name. However, the ERROR message shows: pair gran allows only one compute of type pair/local. I cannot figure out why one cannot use two compute pair/local?

After the above test, I deleted the 2# command and just use the 1# command. When I want to output the results, I used:

hello everyone,
I am a new user of LIGGGHTS. please suggest me some good tutorial where every topic is covered step by step, which is really good for beginners.
I will be really happy if anyone kindly tells me how to create layers of different particles in a hopper at once.
looking urgently for a reply.

best,
Tarun

Hello everyone, I would like to ask for your help in a script that I am working on

It consists of three particles of different sizes but of the same material and a different material geometry.

The problem is that I can not achieve cohesion or adhesion between the particles and the walls but if between the particles

atom_style sphere
atom_modify map array
boundary m m m
newton off

I'm having trouble implementing shrink wrap boundaries. I keep getting an "illegal simulation box" when I use s boundaries, but it works for m, p, and f boundaries. Does anybody have any idea what's going wrong? Here is my script:

atom_style hybrid granular dipole
boundary f f f
newton off
atom_modify sort 100 0.6

communicate single vel yes
units si
processors 1 4 1

region reg block -1.5 2 -.2 .2 0 2 units box
create_box 1 reg
neighbor 0.005 bin
neigh_modify delay 0

hard_particles no

Hello,

I am trying to make reflective walls similar to the fix wall/reflect command (which, for some reason, is no longer available in the current versions of LIGGGHTS). The reason for this is I have the simulation spheres passing directly through rapidly moving walls, rather than impacting them. In order to try to solve this, I have tried using higher Young's moduli (Y= 1e10 Pa), reducing the timestep (once to .0000000005 sec, which still caused wall penetration), none of which worked. My question is