LIGGGHTS® - User Forum

I am implementing a contact model that allows particles to overlap. Is it possible to get information about the density of a region in space such that I would allow overlaps only if the density is lower than some given parameter? For example, lets say I have a system with identical particles (spherical, density = rho, radius = R). Suppose 3 particles overlap and occupy a region in space. Is it possible to get the density (3*rho, assuming they add up linearly) of the region. I am trying to build a contact model based by putting a bound on the density of a region.

I am getting error while inserting multiple particles as below:

```
If you perform one of the steps above LIGGGHTS(R) needs to be recompiled to generate the optimized code.

(/build/liggghts-YO7u74/liggghts-3.8.0+repack1/src/contact_models.h:364)
ERROR: Fix particletemplate/sphere (id pts2): invalid radius random style (/build/liggghts-YO7u74/liggghts-3.8.0+repack1/src/fix_template_sphere.cpp:199)

```

Any I idea , what did I miss here?

Here is my script

Hello everyone,

i am now working on a project with the LIGGGHTS_WITH_FLEXIBLE_FIBERS. I'd like to write out the number of the particles of each bond. Do you guys know, if it is possible? Any hint is appreciated.

Best regards.

I'm currently working on a particle packing simulation where I'm using a script to insert particles and simulate pressing. I want to extend this script to insert a second layer of particles on top of the first, with a different composition ratio of the same two particle types. After both layers are inserted, I would like to proceed with the pressing simulation. I have managed to insert the first layer successfully, but I need help modifying the script to add a second layer with a distinct composition.

I will provide you with some snippets of my script for simplification:

I simulated with multisphere in the liggghts-PFM version, acquiring a portion of the specimen via the displace_atoms command and delete_atom command. Both commands work, but after continuing to run, the intercepted portion goes back to its original position. displace_atoms doesn't seem to work, why is that? Is the particle location not updated correctly?

region bc block 0 1 0 1 0 1 units box side out
displace_atoms all rotate 0 0 0 0 1 0 30
delete_atoms region bc

Hello everyone,

Please be kind enough to explain me the meaning of following two errors.

WARNING: The following model does not yield consistent results with coarse-graining: cohesion model sjkr
WARNING: The following model does not yield consistent results with coarse-graining: rolling model epsd2

Hello everyone,

I'm currently working on a simulation involving a box where the particles inside undergo a volume expansion of 100%. My objective is to calculate the critical stress within the box by applying a compressive force, when the simulation box will alternately expand and contract.

Up to now, I have managed to simulate the expansion and contraction of the box and the application of force on its walls as separate processes. However, I'm facing challenges in combining these two simulations to run concurrently.

Hello mates,

Is there any paraview plugin for the LIGGGHTS_Flexible_Fibers available for newer paraviews? The one from Richti83 is for the Paraview 5.8.1 which is apparently too old for our IT-dept. in the company (only 4 years old bullshit). They are ignoring to download the one from Richti83:

https://github.com/richti83/ParaView_Reader_for_LIGGGHTS/tree/master/pre...

Any hint would be highly appreciated. Thanks in advance

HI,

I'm trying to implement a rigid body dynamics problem in LIGGGHTS. I am using variables as inputs for the fix move/mesh commands. For the linear/variable style there's no problem, however, the rotate variable style only accepts variables as inputs for the angular velocity omega. I would like to also use variables for the inputs of the origin and axis arguments. Is there a way of doing this?

Thanks for your help.

Best regards.
Miguel

Hello,

I want to use spheres and one superquadric (cylinder) in my simulation. However, it turned out to be illegal when I tried using two types of atom (atom_style granular; atom_style superquadric).

I know I can still use superquadrics to represent sphere (just set both "blockiness" as 2), but, in this case, the rotation is not updated and the angular velocity is always 0.

I use nve/superquadric (scheme 1) for integration:

fix integ bed nve/superquadric integration_scheme 1

So, how should I deal with either problems?

Thanks