LIGGGHTS® - User Forum

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

I have gone through the move/mesh command, it gives the option for linear, wiggle, riggle, viblin and vibrot type of mesh motions. However, I want to achieve the elliptical type motion of the body. It is for the simulation of industrial screens. So, it is like there is an inclined meshed screen. The screen should move in the elliptical path without rotation or changing the angle (as shown in the attached figure).

How is it possible to achieve in LIGGGHTS? Someone, please help.

Hi everyone
I am doing triaxial test simulation, and I am unable to control the strain rate of the servo wall.
Can anybody help me in this. I want to attain the strain rate of 1.25 mm/min.