LIGGGHTS® - User Forum

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.

Hello.

I have some question about the mutual consistency of the damping coefficients for Hertz's contact model.
From doc for gran/hertz/history (I use liggghts-1.5.1) I got:

gamma_n / gamma_t = 1/2 * (Y/G)^(1/2)

From my own solution for Hertz and Mindlin equations I got:

c_n / c_t = (5/6)^(1/2) * 1/2 * (Y/G)^(1/2)

Comparing my solution with liggghts I see that,

gamma_n = c_n
gamma_t = (5/6)^(1/2) * c_t

Hi,

since version 3.0.1 was released and there are some changes (http://www.cfdem.com/node/42), I updated the basic setup tutorial for Ubuntu(>12.04)/Mint(>14) and maybe other distributions. There is jpg and png support for dump image and back again - mpi support. It's a basic install, without additional packages and tools. The syntax highlighting for gedit was updated to LIGGGHTS version 3.x.

My problem is that i want to rotate a solid body around his axis but this body is rotated by an angle of 40° an moved in my testing area. (as you can see in the picture).

Now the command to rotate a body is for example:
fix move all move/mesh mesh cad1 rotate origin 0. 0. 0. axis 0. 0. 1. period 0.05

So my problem is that i can't explain myself how to modify this command. I hope someone can help me.
Thanks