LIGGGHTS® - User Forum

Hi, all

Could someone please tell me how to use the compute pair/gran/local and the dump local command to output pair forces in detail? I do not know how to use them. Actually, after dump the pair forces, it will be possible for me to extend the pizza.py to realize them in Paraview.

Could I add these two lines in the input file?
.....
compute 2 all pair/gran/local force
.....
dump dmpf all local 1000 dump.force c_2 #or c_2[1] c_2[2] c_2[3]
................

Hi, Christoph. I have a question about Rayleigh time:

Question 1:
in code:

rayleigh_time_i=M_PI*r[i]*sqrt(density[i]/shear_mod)/(0.1631*nu->values[type[i]-1]+0.8766)

in doc
dt_r =PI*r*sqrt(rho/Y)/(0.1631*n+0.8766),

but in doc Young Modulus instead of shear_mod, I want to known, which was right?

Question 2:

what are the Rayleigh time and Hertz time relationship with timestep of run, and how timestep should be determined.

Question 3:
Are there some references about this topic?

Thank you
xz

Hi every one,
I am a new user of LIGGGHTS. I have installed it and working on it for a couple of weeks. Now when I am running my input script, it is giving me the following error.
"error while loading shared libraries: libimf.so: cannot open shared object file: No such file or directory"
What this libimf.so shared object is? Why it is missing now while every thing was fine a few days before?
I have tried to recompile it but is giving errors
Thanks in advance.
Naved

Hi,
Why I can not dump correctly the stresses on moving mesh? How frequent should I dump? Can I dump like this frequency :
dump dump all mesh/gran/VTK 1 dump*.vtk stress cad2

Thanks in advance,
Ram

Hello everyone,

I have some troubles to use the command fix move linear.

The function fix move wiggle works fine: fix 3 top move wiggle 0.0 0.01.0 1.0 units box

However when I try with : fix 3 top move linear 0.0 0.0 1.0 or fix 3 top move linear 0.0 0.0 1.0 1.0 units box

The simulation does not work. Please, can you correct my error so as to I use this command ?

Regards
JF

Hi,
I want to change the density of already poured particles in the simulation box. Can I change it with fix adapt command or set command? Or, I should re-pour the particles (with new density) if it is not valid way of doing the simulation.
Thanks in advance,
Ram

Dear Liggghts developers,

is there a PDF documentation of LIGGGHTS available, that I missed somehow at this website.

The reason why I ask is, the finnie-wear.pdf looks like an extract of a larger documentation and I wanted to check the reference, which is given for the Finnie erosive wear model.

With kind regards,
Thomas Wagner.

Hi,
I want to dump force on particles with following commands but it prompts an error. The statements are:
.....
compute 2 all pair/gran/local force
.....
dump dmp3 myGroup local 1000 force,txt c_2[1] c_2[2] c_2[3]
................
When i run the simulation, the following error stops my simulation:

ERROR: Dump local compute does not calculate local array

Please anybody guide me, thanks in advance...
Best,
Ram

Hi!
How can i print the instantaneous time of my simulation in my dump file.Can anybody help?
Thanks
sajjad

Hi,
I am pouring small particles in simulation box containing one big particle, during pouring I get this message many times:
INFO: more than 255 touching neighbor atoms found, growing contact history.

After a few timesteps my system slows down and stops working. Can anybody tell me about the problem?
Thanks,
Ram