LIGGGHTS® - User Forum

Hi Christoph,

I have done such similar job by using commercial codes. There are 2 methods to generate a non-sphere particle: 1) cluster spheres together as a single particle, the bonds between spheres can be broken; 2) particle is formed by number of overlapping spheres as a rigid body, bonds can not be broken.

Since the feature 'multisphere' is not yet available in both 1.5.3 and the latest version, according to previous posts. So i was wondering, is it possible to bond spheres ( overlapping or non-overlapping) together using method 1 in Liggghts/Lammps.

Cheers,

Hi everyone!

I am aiming to get started using CFDEM and just finished setting up all components necessary for that. All in all I now have up and running:
- OpenFOAM-2.1.x incl. ThirdParty-2.1.x (built from source)
- LIGGGHTS 2.1.1
- CFDEMcoupling 2.4.4
- current version of lpp
I tested each part of the installation running the respective tutorial/example cases: OpenFOAM, LIGGGHTS and CFDEM seem to work as expected.

Dear all,

I'm trying to change the processor size after I save the result from a serial version of LIGGGHTS and want to run the parallel version to continue the results. I define the prossessor dimensions before the read_restart comand but it shows an warning and error message as:

WARNING: Restart file used different 3d processor grid
orthogonal box = (-0.00106955 -0.00106955 -6.95546e-05) to (0.00106955 0.00106955 0.00206955)
ERROR: Bad grid of processors

Dear LIGGGHTS Community,

I was just wondering if someone could explain me how to visualize or use the data calculated by the pair/gran/local function defined as :

compute forces all pair/gran/local id pos force
dump forcedump all local 400 post/dump.force c_forces[1] c_forces[2] ... c_forces[12]

I posted this a couple of weeks ago about my jobs stopping early. I'm trying to fill up a "2D" hopper with particles, remove the piece at the bottom, and let the particles drain out, but I would get some sort of error and my job would end early (and it seems like it always ends on timestep 77000 of X). The only response I received was to update to the latest version. I am now running LIGGGHTS 2.1, and I'm getting the exact same issues.

Hi there,

Im pretty much very new to all this and I have got all the files, programs and features up and ready. Is there any advice/tutorials/books I can look at for developing a DEM exercise to model a simple vibrating hopper with small to medium sized media (12-15mm Dia glass bead)?

If anyone can help, it would be much appreciated.

Many thanks

Gwyn

I looked in the manual, but I couldnt find reference to this;

+ Fixed a small glitch in the new "output" option of the dump mesh/VTK command. Thanks to Philippe Seil (JKU) and Christian Richter (OVGU) for noting this.

I would like to try out this new feature, but am not sure how to set it up. Maybe the chute_weat example could be updated with this new option?!?! Or someone could explain where I can find documentation on this.

Kirk

OK, thanks I found it.

I modified the dump mesk/vtk line in the chute_wear example to read;

Hi!
Does anybody know, how I can make particles exiting a domain in LIGGGHTS-PUBLIC? I have defined the walls of the system as the STL-surface, and as the particles pass certain xy-plane, I want them to exit from domain. In the older version of liggghts in defined z-boundary (i.e. the xy-plane from where I want the particles to exit) inside the stl-surface and defined it as 'f'. Now I'm getting an following error:
ERROR: Mesh elements have been lost (multi_node_mesh_parallel_I.h:508)
Any ideas how to fix this?

- Timo

Hi,
For the calculation of stress/atom it seems only the neighboring particles are accounted for but not the contact forces that occur between a particle and a wall. Is this by design or something that might have been overlooked.

Thanks,
Tapan

Hello,

I'm running into a problem where my code exits early without giving me any obvious error messages. I'm simply trying to pour particles into my hopper. I'm submitting jobs batch style to a shared computer network.

I have the fix/insert set to use massrate. If I set the mass rate too low, obviously all the particles won't be generated before I run out of timesteps. However, if I set the massrate too high, for some reason the job will stop in the middle of execution. In this case, it stops after the second attempt to insert particles - step 1001.