LIGGGHTS® - User Forum

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?

Hey guys,

Is it possible to do a fix command in a defined region (within the simulationbox) or is there a way to do a fix-command in a loop or in an if-condition? I tried different ways but it does not work.

Thank you!

Dear community,

I created new contact model and want to verify with analytical/numerical solutions. Does anybody know how to create particles (2 or 3) with predetermined position (known center and radius)?

Best , regards Furkhat

Hi,
I am interested to know method/s to calculate coordination number for superquadrics. The following commands are existing and are meant for spheres:
(compute contact/atom
compute contact/atom/gran
compute coord/atom)

Thanks,
Sounik

Hi,

I am very new to this filed and I am planning to simulate the powder spreading process.
I have a question about what the insertion region mean? Why we need to set that?

Thanks,
Mill