LIGGGHTS® - User Forum

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.

Hi,
Can anyone who has used the cohesive model provide some references to realistic values of the cohesive energy density (J/m^3) parameter for some common materials like say wet glass beads or wet sand ?? I know that the value can vary quite a bit based on the amount of wetting and other parameters but it would help to atleast know some ballpark figures.

Thanks,
Tapan

Hello Liggghts Users,

I am new to liggghts and lammps too. I am trying to make changes in the example files (LIGGGHTS) by assigning external electric field using Fix. But I am unable to set charges to the particles using SET command.

The error says : Set command with no atoms existing.

Can somebody explain what I am doing wrong ? or how to assign charges in example file "in.conveyor". (*Sorry for such a stupid question*)

Thanks,

Best Regards,

abhishek

Hi,
Is there a repository from where I can download the previous version of LIGGGHTS (2.0.6) ? I installed version 2.0.7 and I am getting some peculiar results that I was not getting earlier. However before I blame it on the new version I wanted to rerun my code with the older version (2.0.6) to make sure.

Thanks,
Tapan

Hi everybody,

I am trying to install:

• fftw-2.1.5.tar.gz
• openmpi-1.4.5.tar.gz
• liggghts-2.0.6 from git clone from LIGGGHTS-PUBLIC.git

The results are following:

• The installation of FFTW went smoothly.
• The installation of OPENMPI went smoothly too. A simple “hello_world” test gave results as expected, as well as the “mpirun” command.
• The compilation of Liggghts went through without any major problem, except maybe the three lines at first:

Hello Liggghts Users,

I like to use DEM method for charged particles such that they can interact with external electromagnetic field. So I have following questions :

1) Is it possible to define external force field for example Electrostatic force as an analytical expression ?

2) Is it possible to use external field a numerical solution as calculated from other FEM package i.e. field values over a grid of points and use the interpolated field etc. ?

Sincerely,

Abhishek