LIGGGHTS® - User Forum

Hi everybody,

I am showing the force chains of a granular assembly obtained from LIGGGHTS using Paraview.
Problem1: Scaling is occurring in the reverse order, i.e. the weaker force chains are thicker and the strong force chains are thinner.
Problem2: Horizontal lines can be seen joining the lateral boundaries.

PS: I am using periodic boundaries at the lateral boundaries

Any suggestions will be very helpful.

Thanks,
Sounik

Hello,
I need to compute some parameter that relates the forces on particles to the force on contacts. I assumed that if particle i have n contacts, by adding up the forces at each contact I will recover the total force on the particle (without external forces). Unfortunately, that does not seem to be the case.

Hello!

Hi,

I would like to know if it is possible to define the initial position of a multisphere in LIGGGHTS (eg. placing a cube in the bottom of a tank) instead of inserting it at random places in a domain?
Also, in the "multisphere_stone_restitution" example, I did not understand how the atoms' positions were defined: in the "stone1.multisphere" file, the x, y, z coordinates are all positives, but when I output the results in Paraview, the x and y coordinates are negative. How are the atoms' positions actually defined?

Thank you for your time,
Andrea M.

Hello!

I am a new user to LIGGGHTS and I have been doing a research related to the centrifugal compaction of metal powder particles. I have set a simulation which is taking quite a long time on my laptop.
I have set the thermo command to show the status each 10000 steps (there are 8E7 steps in total). I have noticed that while in the beginning after 1 hour 1 million steps have been completed now the simulation is much slower and now in 1 hour there are about 300 000 steps completed.

How can I rotate a region I created by intersecting other regions? I know this can't be done directly , is there a way around it?

Many thanks

Hi, I'm trying to run a case on cfdem, the liggghts simulation runs with a reading a restart file written by another script and now that I run the case it gives me the error below, while there is no set command in the liggghts script.

Executing command: 'set region total property/atom 600.000000 '
set region total property/atom 600.000000
ERROR: Set command may not be used together with fix multisphere (../set.cpp:113)

Hi,

I want to have a massrate that vary in function of time. Is it possible with Liggghts 3.8?

Best regards

Michael Page

Hi, I'm trying to do a cfdem simulation, I try to read a restart file with a liggghts script that contains multi sphere data generated by another script. when compiling the second liggghts script I face an error, incompatibility of fix and set command in multi sphere script. after reading the multi sphere restriction I deleted the heat transfer commands (set command included) and now another error with fix gravity shows up. I read the fix and fix multi sphere command description but I don't know why I get this error? I'll be grateful if anyone has an idea. thanks in advance

Hi everyone
In some papers, the authors increasd the particle density a thousand times to increase the time step.
Can we do that in LIGGGHTS? Is there any paper refer to it?
Best regards