LIGGGHTS® - User Forum

Hi Liggghts Forum,

I have a compressed box of particles. The top layer of the particles needs to be moved horizontally in one direction(+y), while the bottom layer in the opposite direction(-y).

I created two groups (edge & edge1) for the particles in the top and the bottom layer respectively. My command for moving the particles are:

fix edge all move linear 0.0 0.08 0.0 units box
fix edge1 all move linear 0.0 -0.08 0.0 units box

Hello,

I am currently running simulations on 2 computers and have found a clash in the output of the same the dump command.

The dump command i'm using is "dump dumpstress all mesh/gran/VTK 1000 dump/dump*.vtk stress cad1"
However, the vtk dump files are formatted differently for each computer I use (and this is affecting my post processing work).

When I want to build my LIGGGHTS to be a shared library, I always got this problem. And I have install MPICH as the tutorials, but the problem is still exist. I am a new learner of liggghts, I will very appreciate if you can help me

I am trying to setup a simple one particle simulation with periodic boundary conditions (PBC) in LIGGGHTS and LAMMPS. I am finding that the atoms are lost in LIGGGHTS-PUBLIC (v3.8.0 ), whereas the same simulation except for a minor change in the communicate command seems to work fine in LAMMPS (17 Nov 2016). Please let me know if I have to include additional commands when I try to set up PBC in LIGGGHTS. I have attached the minimal examples for your reference.

Hi,

When I was using the si unit system, the simulation can run without error. However, when I want to change to cgs unit system and convert the density constant from 2500 to 2.5, there is an error saying "Mesh elements have been lost / left the domain". When I set the density constant to 2500 the error is fixed.

So, I am wondering what is the unit for density constant in cgs system?

Here is my input script.
# Moving mesh example

atom_style granular
atom_modify map array
boundary f f f
newton off

Hi,

I was wondering if someone can clarify for me how the stress between a particle and the wall is calculated? I am outputting the normal stress after setting the mesh to track the stress, and I ultimately want to use the stress to calculate the total force on the mesh. I specify the mesh as follows:

fix m1 all mesh/surface/stress file meshes/filename type 1 stress on

And then I dump the resulting force using this command:

dump dumpstress1 all mesh/gran/VTK 100 post/filename*.vtk output face area stress m1

Hi,

I am new to the LIGGGHTS and I just want to simulate the powder spreading process. I have the STL file of a roller, and a surface to store the powder. But when I was doing the simulation, the particles always pass through the wall I imported from an STL file. Can anyone help me with this?

Thanks,
Mill

The input file:
# Moving mesh example

atom_style granular
atom_modify map array
boundary f f f
newton off

communicate single vel yes
units cgs

Hello everyone

I have been trying to use multisphere/break command to break the particles when it attains certain kinetic energy during its fall under the influence of gravity. I am unsuccessful in doing that.

source code : fix_multisphere_break.cpp

what does this two lines indicate in the source code

if (triggerName_ && update->ntimestep % modify->fix[triggerIdx_]->peratom_freq)
error->all(FLERR,"Fix used in fix multisphere/break not computed at compatible time");

code :

Dear LIGGGHTS users,

I am wondering whether LIGGGHTS can capture particle contact at periodic boundary. Using periodic boundary condition enables particles to move continuously from one to other sides of particulate domain. If particles position very close to the boundary line, a part of their volume is out of the domain and should contact with other particles positioning at opposite side. Are these contacts considered in the current LIGGGHTS ?

Thank,

Regards,

Nathan,

what atom style should be used to have cubic particles for segregation.Will superquadrics atom style work by specifying blockiness of 300?