LIGGGHTS® - User Forum

Hello all,

I am running a shear test simulation and I would like to see some force chains. I use the command
" compute fc all pair/gran/local id pos force"
but because of that my simulation results change.

Hello

I m working on a research project and i want to dump f_surfaceLiquidContent[0] but it seems like it s giving me wrong values, im attaching my script and the results with you, so can someone please gives a help

Hi all,

i have a cylindrical shear cell geometry. In order to lower the computational cost i want to use periodic boundaries. I know that i can not unfortunately use "pie slices" (sorry if thats not the correct term) only boxes. The geometry has the be able to rotate also to simulate shearing.
Is there a way to simulate half of the shear cell with a cartesic periodic boundary approach? How can set this up? Are there any other possibilities to reduce computational time i can think of?

Thanks a lot this forums helps tremendously.
Kind regards

I want to ask about using different contact models for superquadric particles. I can see only the following contact models are available in the "style_contact_model.whitelist" file for superquadric particles:

GRAN_MODEL(HOOKE, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_OFF, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HOOKE, TANGENTIAL_NO_HISTORY, COHESION_OFF, ROLLING_OFF, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HOOKE, TANGENTIAL_NO_HISTORY, COHESION_OFF, ROLLING_CDT, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HOOKE, TANGENTIAL_NO_HISTORY, COHESION_SJKR, ROLLING_OFF, SURFACE_SUPERQUADRIC)

I read in restrictions for atom_style command document (https://www.cfdem.com/media/DEM/docu/atom_style.html?highlight=superquad...) that superquadric style is not available yet for public version?

Is that true or the document is not updated?

Hello everyone, I am doing a simulation of wear in a mining truck hopper ... this study consists of 3 cases with 4 different sizes of spheres, (case 1: 180, 220, 280, 340; case 2: 340, 400, 440, 500; case 3: 500, 540, 600, 660 [mm]).
In case 3 I receive the error in the title, I understand that I should increase the value of the "neigh_modidy" command but I don't understand what value I should choose. It would be very helpful if you could advise me which value to choose.
Finally I say goodbye to everyone. Greetings to all.
attached input script

Hello everyone,

i used normal spheres until recently and the simulations went fine.
Now i have to study the effect of different particle shapes in my Simulation so i set up my Simulation for multispheres. Now when i run my simulation the Particles after quite some time in the run are doing crazy things like suddenly "exploding" and worst of all clipping through the container where they are supposed to get shuffled around.

So basically the stuff you see when the time step is too large to catch the particle interaction correctly.

I want to servo the wall with a target confining pressure in LIGGGHTS. But, there are only "target force" that can be choosn in LIGGGHTS. So, we need to obtain the area of the wall and update the area timely. It confuses me a lot.

In addition, can we define functions, use "if" statement and "for" statement like python and other high level programming languages?

I look forward to your answers very much, if you have the relevant code, I would not be very grateful.

Thank you!

Wang Xiukai

Hi all,

i am running simulations on a redhat cluster and found that the number of particles that are added during a run is depending on the number of CPU's i use for that.
So for example if i use 8 Cores i get the number 44K particles that are added but if use 16 cores with the exact sam in-file i only get 32K particles also i get an error about the timestep being suddenly too large which i haven't encountered running on my local machine with 8 cores.

Is this a known problem? How can this be fixed?
Thanks for your suggestions!

Im trying to insert particles in a stream from a ternary number based distribution and the resultant distribution does not resemble the desired one.