LIGGGHTS® - User Forum

Hi all,

Edit by Arno Mayrhofer: Please do not follow this outdated guide. Instead see the last post in this thread for details.

Hi

May someone assist me on how to extract shear force from a moving wall relative to a static mass of granular materials which are loaded with a normal force.

What options are available for relaxing a multisphere system? My favorite fix option is nve/limit, but this only works for regular spheres. And I'm running simulations in parallel, so inserting over 100,000 multisphere particles has been very difficult if I use the 'overlap_check yes' option. I'd also prefer to keep my domain as compact as possible, so I want to avoid inserting particles from a very tall height. If there is nothing freely available, does anyone have any recommended code modifications I can implement?

Hi all,

Hi all. I am currently doing a simulation that takes dump files of a 1.5 million particle granular slide every 2000 timesteps. Each ascii .vtk file takes up about 150 MB and the granular slide concludes in about 5000000 timesteps; i.e. the final file size of the dataset is roughly 375 GB. I am looking for ways to reduce this filesize while preserving the same data as each save interval corresponds to a frame in my laboratory recording video. Is there any way for LIGGGHTS to dump into a compressed folder for instance, and how much space would that save?

Dear All
I want to run heat transfer example to check the heat flux in the all directions. But I faced with below error:

ERROR: Dump custom fix does not compute per-atom vector (../dump_custom.cpp:1385)

My only change in the script is (in the heattransfer_2 example):
dump dmp1 all custom 800 post/dump*.heatGran id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius f_Temp[0] f_heatSource[0] f_directionalHeatFlux[0] f_directionalHeatFlux[1] f_directionalHeatFlux[2]

Dear LIGGGHTS user:

I met an error when using write_data for output as following information:

....
run 1000000

write_restart pour2.rst
write_data data.pour
ERROR: Unknown command: write_data data.pour
(/build/buildd/liggghts-2.3.8/src/input.cpp:214)
...

I am puzzled what is going wrong?

Hi everybody,
I could not find anything about this in the forum yet, so maybe I missed it. But I have experienced something weird lately.
When I run the same simulation on 1 or 2 CPU I get different results. And by different I mean slightly different in the trajectory and the forces.
You can check this with the tutorial movingMeshGran. It does not matter how often you run it on a single core, the result is always the same (checked with diff on the dump files, no difference). As soon as I start a parallel run they differ. And not only this, 2 CPU differ from 4 CPU usw..

Hi everyone,

I have a question about number of bins and bin size when using neighbor bin command.
I have read some post regarding to Too many neighbor bins, and it seems that LIGGGHTS limit the number of bins to 200. I tried to figure out how to estimate the number of bins.

number of bins = half size of simulation domain(in xyz direction)/bin size, is this correct?

the optimal bin size is 2*max radius or 4*max radius?
because I find tow posts discussing this setting.

Thanks
Weijing

A beginner here. Successfully cloned LIGGGHTS 3.6.
Successfully made and build VTK 7.1.1 using CMake and VS2010.
No issue in making LIGGGHTS 3.6 with CMake. However, building in VS2010 shows 157 errors!!

It would be so so great, if anyone has recently installed LIGGGHTS on any windows platform (preferably Win 7) using Visual Studio (preferably 2010) and can give some help.