LIGGGHTS® - User Forum

Dear all,

I want to use the values of per-atom vectors at each time step in "compute property/atom" and check them in an if loop afterwards. I have written this part of the script for this regard:

compute ff all property/atom update_on_run_end yes fx fy fz
variable fmag atom sqrt(c_ff[1]^2+c_ff[2]^2+c_ff[3]^2)

How can I access the vector fmag at each time step in the if loop?

Thanks in advance,
Nazanin

Hello everybody,

I have the strange behavior that my simulation suddenly stalls and does not proceed. There is no error message. With one case, this behavior appears always around the same timestep. When I slightly modify the case, for example move the mesh a little bit or set particle heat sources a little different, the case either finishes or stalls at a different timestep. The problem is that I don't know how to tackle the problem.

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