LIGGGHTS® - User Forum

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

I'm running a simulation in which a bin is initially filled with equal masses of two different particle types (identical properties except radius), and then opened at the bottom to allow the particles to pour out. Can anyone help me figure out how to get the code to print out the number of each particle type remaining (or equivalently, the mass) using the thermo command?