LIGGGHTS® - User Forum

Hi everyone,

i am working on a liggghts simulation of a plastic extruder for my master thesis.
On my adventure with DEM i noticed that the soft particle approach wants to have only small overlaps between particles (< 0.5%d).
In my real life case the particles are getting deformed in their way through the extruder. Wich leads to some questions:

1)How does a Youngs Modulus exceeding the limit of 5e6 Pa change my simulation. (in older versions i had to add "hard-particels: yes")

Hi,

I need a clarification. I am simulation triaxial tests on soil. I am using Servo walls on the sides and top to give a constant confinement and move my bottom mesh with a velocity.

To print the volume, I calculate the position of the walls.

Hello all, I am new in LIGGGHTS, and I need help)
Can I have an example of a simulation where multisphere particles breakdown due to mutual abrasion?

In my project I'm going to simulate abrasion breakdown of particles in fluidizied bed reactor, and I have no idea how to do it.

Thanks, Rustam.

Hi,
I wanted to know that in the following command line:
fix pressdown topwall aveforce 0.0 -1.0 0.0

-1.0 is applied in the -ve y direction to each atoms of the group topwall or to all the atoms together?

Sincerely,
Sounik

Hello experts!

I have some problems with the convergence of the contact point of two touching superquadrics. The contact between two superquadrics remains undiscovered if the blockiness value exceeds a certain treshold. For the attached example the superquadrics with blockiness value n_1 = n_2 = 5 touch each other but if the blockiness is n_1 = n_2 = 10 there is a complete overlap without contact recognition. So far I have not been successful in solving the problem by using a smaller timestep or an alternative neighbor bin size value.

Good Day,

If I have some in.script.sh with a variable

variable a universe 2.0 4.0 6.0 8.0 10.0


Using the code


shell mkdir post_$a
next a
clear
jump in.script.sh


The jobs run one after the other (series). What can I do if I want the jobs to run simultaneously (parallel)?

Thank you.

I am thankful for Christian's contribution for visualizing the superquadric particles on previous posts.

The issue has been well solved. And the youtube link for the video could be found as

https://www.youtube.com/watch?v=T-qAggZhfzo

However, I find it is hard to visualize the superquadric particles with different size distribution. Any suggestions are appreciated.

Kind regards,
lumb

Hi All,

In my CFDEM case I have to insert thousands of particles for that I am using "include" command and I am writing small python script to generate coordinates of particles. With only LIGGGHTS script it works properly but with CFDEM case it does not work. Error is "can not open the script" on include command.

Hello all,

Why in LIGGGHTS the cohesion density energy is in J/m3. When Johnson-Kendall-Roberts theory say that is the surface energy, and that is in J/m2?. What is the relation betwen both of that definitions?. Because in the literature the definition of the cohesion energy density is other than the adhesion, and that is related with chemestry, it seems here is a mistake in definitions. So, the process to calibrate this values with experimental data is confuse.

Please say to me what paper could I can read for understand the approach did for LIGGGHTS with this terms

Thanks