LIGGGHTS® - User Forum

I am a little bit new LIGGGHTS and am trying to create a simulation of multisphere rigid bodies rotating in a cyllinder. However, after researching I am still very confused as to how the fix rigid command works.

How does one combine particles into a group to be 'fixed rigidly'?

Any help in this matter would be greatly appreciated!

Thanks!
Quincy

Hi All,

Fix rigid/small behaves very differently than fix rigid in v3.0.1. It seems like rigid bodies created by fix rigid/small can exert forces on neighbor particles, but the rigid bodies themselves do not move at all. For some reason, it looks like bodies created by fix rigid/small are not being time integrated. In the source code, the integration schemes look the same... Anyone have the same experience?

FYI, my comm cutoff is large enough, I have tried several comm cutoffs with no change in results.

Thanks,
Zamir

EDIT: Attached a test case

Hi

i like to use a lognormal distribution but the ERROR message says this is currently deactivated
is there a chance to activate this distribution?

thanks

cheers
Jürgen

Hi,

I am a new user of LIGGGHTS and I need it only for generating a 3D packing geometry. The 3D packing consist of a cube with five different particle sizes. I am dealing with two issues.

Hi all,

According to the doc pages for dumping the forces on the walls the command "fix mesh/gran/stressanalysis" should be used.

My problem is that I have imported the walls by "fix mesh/surface" and changing it to "mesh/gran" didn't work (got the error: invalid fix style)

It seems to me that "fix mesh/gran/stressanalysis" works only if you have used the "mesh/gran". So I was wondering what do you suggest for dumping the forces on the walls without changing the importating command?

Thanks in advance,
Danial

Hi all,

I use "pair_style none" to turn off the particle interaction.

But it reports the following error.

Dear community,
I'm modelling powder flow and would like to account for cohesion and adhesion. The LIGGGHTS cohesion modules require
a cohesion energy density defined for each pair of materials. Where do I get this parameter from ? I couldn't find it in literature
Is there a way to get an estimate for the cohesive energy density ? Is there any link between this parameter and Force curve obtained from AFM measurements ?

Best regards,
David

Hi
have two problems. The first one is the ERROR message: Invalid atom style (atom.cpp:343) by using

atom_style hybrid granular molecular

this message occurs despite that I installed the molecule package.
(I use the LIGGGHTS-PUBLIC Version 2.3.8)

My second probleme appears by using the create_atoms command.

create_atoms 1 single -1 0 2 units box
set atom 1 type 1 diameter ${Durchmesser}
fix gravi all gravity 9.81 vector 0.0 0.0 -1

Dear all,

I have a question related to LIGGGHTS. I want to save the simulation run in a specific time (make an initial condition for the final simulation) and start new runs based on this saved simulation. For example, suppose that I have inserted particles and the insertion step is completed, the results are saved and I want to start new runs from this point. How can I accomplish this?

Best regards,
Shahab Golshan

Hello everyone

I do not understand how to decompose a problem correctly in parallel.

for example .... ¿what does this decomposition "# processors 2 2 3"?

thanks.