LIGGGHTS® - User Forum

Hi to all,

for gran/hooke there is only one friction coefficient necessary. But in reality are 2 friction states possible: Sliding (or dynamic) friction and static friction. Is there any difference in Liggghts, or is this always the same?

Thx
Orangensaft

Hi everybody,
I had started out with LIGGGHTS a while ago, and know a few basic commands. I would like to know if it is possible to add mass (or) density for that matter, to any of our imported geometries. eg I am importing a box (.stl geometry) and pouring particles inside it , but i also require the box to be of a particular mass. Is there a way to do it ? , or are there any other alternate solutions ? Kindly help.

thanks
anand

Dear all,

I want to dump movie with liggghts in my fedora system. How to change the makefile and make it with ffmpeg support? I've added "-DLAMMPS_FFMPEG" but it failed.
Thanks a lot!

Jian

Resolved....

Done!

I have created 3 .stl geometries using the " mesh/surface" command. Now I want to make to of these to make contact without penetrating one another.
for eg. I am trying to oscillate one geometry , which will hit the other one and this will eventually set the particles in oscillation. Can anybody please suggest how do I go about doing this. I have attached a snapshot of my simulation with 3 different geometries ( 3 different colors). Here, the red one needs to hit the green one.

Hello everyone,
I have done a simulation with a large amount of particles flow down a flume to a horizontal container at the bottom which already has particles in it, I want to know the displacement of the particles at the bottom. By enquiring the Manual, I found the "compute 1 all displace/atom", this command do the job of computing the displace of atom in specified group, but I don't know how to dump out the computed results. Can someone give me help? Any suggestion will be appreciate. Thanks!

Best Regards!
Qiao

Hello,

I'm trying to fill a cylinder with cohesive particles, using Hertz and a certain particle size distribution. However, the particles bounce around and/or then just seem to dissapear. I'm not sure whether they go through the wall or if they bounce out of the domain. Initially, I had no problems, but now I do. Changes I've made include switching from Hooke to Hertz, switching from legacy/pour to insert/stream (to allow a PSD), and adding cohesion, but I'm not sure what causes the problem.

Any help would be appreciated. I've added my code below.

hi all,

dt_h = 2.87*(m_eff^2/(r_eff*Y_eff^2*v_max))^0.2

I understand the concept/calculation of effective mass,radius and young modulus for particle-particle.
Eg: 1/m_eff = 1/m1+1/m2; (m1, m2 are masses of two particles).

How is liggghts code calculating for particle-wall? What can the mass of wall be? Is it going to be infinity?

Please help.
Thank you.

Hello,
I'm simulating an continuous mixer, which mixes molecules and spheric particles.
The molecules are created continuously and inserted in to the mixer. The molecules are stored in group grpm.
The granular particle are generated classically with the fix insert.... command.

Hi

Does anyone have any experience with the "lubrication force" between particles? Is the "lubricate" pair_style in LAMMPS/LIGGGHTS the same as what many papers use as the lubrication force? It looks like a totally different formula in the code.

e.g.: Zhang, W., Noda, R., and Horio, M. “Evaluation of Lubrication force on colliding particles for DEM simulation of fluidised beds”. Powder Technology, 158, pp 92-101, 2005.

Thanks
Evan