LIGGGHTS® - User Forum

I am creating rigid bodies from groups of spheres using, for example,

fix 1 all rigid molecule

From doing some simple tests with two spheres setup as a diatomic molecule, it appears that LIGGGHTS will always output the total energy - translational + rotational - for ke. I want to separate this energy into rotational and translational pieces in the thermo output. LAMMPS seems to have had ways to do this with compute temp, but that does not appear to be a thing in LIGGGHTS. I tried using erotate, but that does not seem to correlate with what I need at all.

Hello
I am currently using LIGGGGHTS-flexible fibers version for granular bonds.
In my simulation I have 2 groups (web & blade), and I want to calculate the force that web exerts on the blade. For that I tried the following command:
compute force_inter blade group/group web

However, I am encountering the error saying that "Pair style does not support group/group".
In the contact style, I am using the following:
"pair_style gran model hertz tangential history "

Can someone please help me to resolve this

Thanks

I would like to count the overall number of collisions between different types of particles.

Suppose we have 3 types of particles

So what i need is the total number of collisions between each type, between type 1 and type 2 , between type 1 and type 3, and between type 2 and type 3, Is there a way to do this?

Do i have to make some changes in the source code of liggghts or use a predefined liggghts command .

Ps: i have 20 different type of particles.

Hi,

I'm looking to calculate the dissipated energy for colliding spheres. In the documentation, the computeDissipatedEnergy option for a granular model references a fix style to use later that throws up an error when I tried to use it - so I am unable to access these values. In a previous forum post I read it seems that this is a premium feature (I am only using the public version). My question is, is there a way in LIGGGHTS-public to efficiently track the energy dissipation?

Hello !

I've been using LIGGGHTS for around a year now mainly with spherical particles. I want to create a '2D' model using cylindrical particles, it would be a 3D plan symmetrical model. To do so I created superquadric particles with N1=8 and N2=2. But whenever I try to use the command 'write_data' to save state the program crashes. I get the following error :

Hi
I am currently using the 'LIGGGHTS flexible-fibers' version. As far as I can see there is option for elastic bonds. Is there a way to introduce elasto-plasticity in the bonds.

Thanks

Hi everyone,
I am a new user to LIGGGHTS and I am trying to simulate a packing including both non-cohesive and cohesive particles and the interaction between them. I already tried to simulate the in.cohesion example in LIGGGHTS/ Tutorial_public but when I tried to add a larger size particle (non-cohesive) together with the existing cohesive particles, I saw no cohesive behaviour between them. Is there anybody has any ideas on how to insert a packing of non-cohesive and cohesive particles? I really really appreciate any helps.

I have been able to use the granular model effectively to simulate monodisperse and binary mixtures of spherical particles. I especially like that I can use read_data to set the initial position/velocity/etc of each individual particle. I now would like to simulate mixtures of particles with more complex shapes - e.g. a mixture of cylindrical particles.

Hello all,

I am trying to simulate the isotropic compression of a spherical wall/bounding box along the negative 'r' direction in spherical coordinates. Can anyone direct me towards the approach to edit mesh_module_stress_servo.cpp(/h) and/or fix_deform.cpp(/h) so that these modules work in spherical coordinates? Thank you very much!

Hi
I am using servo wall to maintain constant force on wall. And I have some doubts.

1. The formula referred in documentation for PID controller
output = kp * error + ki * errorsum + kd * errorchange
I want to print or save the output, error, errorsum and errorchange values. How can I do this in LIGGGHTS.

2. Is there any thumb rule for selecting kp, ki, and kd values.

3. How can I change a variable value in every step.