LIGGGHTS® - User Forum

I am trying to simulate such a dynamic process: two particle impact and bond together, and a new particle comes and hits these two to break the bond or to bond with one of them to form a cluster. The free-to-go particle can again impact with other particles and form a bond (or bounce off).

Work Location: Idaho Falls, Idaho, United States.

Duration: about three months (with financial support for roundtrip and temporary living in Idaho Falls); starting from May 2018.

Idaho National Laboratory (INL) is seeking graduate student internship applicants for DEM simulations for engineering-type applications & research.

Preferred Qualifications:

* Familiarity with LIGGGHTS as a user is a significant plus.

* Research experience in the discrete element method (DEM).

Hi,
In the new version of LIGGGHTS 3.8 there seems to be an issue with writing files with .gz extension, which was working fine in previous versions. Taking the periodicChannel tutorial in CFDEM as example, in the file DEM/in.liggghts_init, adding gz to dump file name:
post/dump.liggghts_init.gz

and running parDEMrun.sh gives the following error:
ERROR on proc 0: Cannot open gzipped file (../dump.cpp:460)

If I run the same case in previous (LIGGGHTS 3.6) it works fine. Would you please let me know where the error is stemming from.
Thanks

Has anyone else had issues where dump image blows up using the bonds package?

Hello,

I am trying to simulate the angle of repose test. On every case, particles roll over the lower surface : no cone is forming.
I use this parameter to modify my results without success :
- Coefficient of restitution particle–particle
- Static friction coefficient particle–particle
- Rolling friction coefficient particle–particle
- Coefficient of restitution particle–wall
-Static friction coefficient particle–wall
- Rolling friction coefficient particle–wall

Do I have to use cohesionEnergyDensity ?
Any help?

Is Liggghts allow the Brownian motion of particles?. I want to use this in my attractive particle. Please let me know about this, any alternative idea would be appreciated. Thanks

Hello,

How to use this command please:
element_exclusion_list write

Problem is: 12 elements have high aspect ratio....
Mesh contains highly skewed element....
9 mesh elements have a really unreasonably high aspect ratio....

Hi all. I am currently adapting an old script of mine, replacing spherical particles being released down a ramp with multisphere particles. This has worked for the most part, but when I try to delete some particles from the simulation when the slide mass has settled and is ready to be released from the shutter, more and more particles keep disappearing between timesteps and some particles become fixed in place. The delete_atoms command successfully deletes the particles outside the region I'm interested in (and any spheres connected to those particles in their respective multisphere).

Hi everyone,

I am trying to implement my own heat transfer model but it request a neigh list including non-contacting particles. I managed to do that by using cohesion model together with contact model, which built pair_gran list including non-contacting particles.
however, is it possible to modify some codes to directly use the neigh list before building pair_gran list? I have looked at the pair_gran_base.h, but not understanding clearly. could someone give some hints?
Thanks
Weijing

Hi everyone,

I'm using the following compute for accessing particle-wall contact information:

compute fc all wall/gran/local pos vel id force contactPoint

and the following dump command for writing that information to an output file:

dump walldmp4 all local 1000 post1000/fc*.dump c_fc[1] c_fc[2] c_fc[3] c_fc[4] c_fc[5] c_fc[6] c_fc[7] c_fc[8] c_fc[9] c_fc[10] c_fc[11] c_fc[12] c_fc[13] c_fc[14] c_fc[15] c_fc[16] c_fc[17] c_fc[18] c_fc[19] c_fc[20] c_fc[21]