LIGGGHTS® - User Forum

Hi All

Hi!

I was wondering if there is a way to create composite objects in LIGGGHTS made out of other objects. For example, building a tetrahedron out of 4 spherical atoms.

If this is not possible, are there other ways to create objects with more complex geometry that can move and interact like atoms? I would like to create these objects but still have the "smoothed" spring-like model for interaction between each other.

Stefan

Hi All

I am trying to run the LIGGGHTS granular pair style with an "old" LAMMPS pair style. To do this I am using the "hybrid/overlay" command to include the effects of both pair styles. My input script runs fine with the plain granular system, but as soon as I use the hybrid/overlay command I get a segmentation error as given below (the first line shows the last line that was reached in my input script):

fix wall all wall/gran/hertz/history 1 0 mesh/gran 4 bottom top inner outer
[dwain-dunn:03288] *** Process received signal ***
[dwain-dunn:03288] Signal: Segmentation fault (11)

Hi,
I'm creating atoms region by lattice command inside a .stl container.
This works ok but I have a "problem" when I create the .vtk: the particles are as scaled respect to my container.
In detail:
- I created a cubic box region of b = 0.3 m edge length.
- My .stl container is in the middle of box with l = b/3 m edge length.
- I defined the lattice region inside this container (you can see the file in the .txt attached file).

Hi,

We're using LIGGGHTS to study a problem in materials handling for the minerals processing industry. Particles enter into a rectangular containment vessel from several defined feedport regions near its roof - this is to simulate material flowing into the vessel through feedports from storage hoppers above (for various reasons we don't want to model the particles inside the hoppers themselves). The idea is that the vessel slowly fills up with particles until they physically block the feedports, at which point the feed rate into the vessel slows down or stops ("choke-fed" condition).

Hello Christoph, I would like to include a flag that changes its state when a particle touchs for first time the wall. This is like the:
touch = firsttouch[i];

in the pair_gran_hooke_history.cpp compute function. I want to see when the contact is lost in order to make some variable assignments. So in: void FixWallGran::post_force(int vflag), I can modify the code and make something like:

if (wallstyle != MESHGRAN_FWG){
rsq = dx*dx + dy*dy + dz*dz;
if (rsq > radius[i]*radius[i])
{
if (touch[i]){
touch[i]=0;

I encounter difficulties in running a 2D simulation. A rigid rod consisting of 200 atoms is attached to a spring. The rod should only move in the xy-plane. Therefor I put 'dimension 2d' in the input file, then setup a simulation box with a small z-dimension with periodic BCs in z and fix enforce 2d. The atoms are treated as a rigid rod via the fix rigid command with force components in x and y direction and torque around the x-axis. NVE integration should be done with fix rigid.

Although I apply a strong spring force, the rod doesn't move at all?

Dear Sir/Madam

I am a beginner to LIGGGHTS. I have installed ICC, OpenMpi, FFTW, PARAVIEW and LIGGGHTS in my Ubuntu 10.04 Lucid platform.
Please guide me to get started with LIGGGHTS. How should I proceed. At some beginners tutorial should be provided.

Please help.

Rahul Kumar Soni
Indian School of Mines
India
http://sites.google.com/site/ismrahulsoni

Hi, Christoph, i have a question about the difference of pair_style in LIGGGHTS and LAMMPS. As LIGGGHTS manula discribed, the stiffness and damping coefficients in LAMMPS are now derived from the material propeties (e.g. Young's modulus, poisson ratio).

Hi,
Is it possible dump forces on stl?
I'd like to save a dump file to then create with pizza a surface vtk file with force field (like a patch).

Thanks for any reply

Andrea