LIGGGHTS® - User Forum

Hello everyone,

Would anybody happen to know how velocity is computed for Super-quadrics particle?

One of the papers I found stated that Equivalent Sphere Diameter of Superquadrics particle is found by 3th Root of (6*a*b*c)/pi.
And, they also state that Equivalent Sphere Diameter of Superquadrics particle can be used to find Reynolds number by U*dv/kinematic viscosity.
(Paper: Numerical investigation of drag property for fluid flow through packed beds of super-quadric chip-like particles)

Hi Everyone,
I am trying to simulate a case with a two-particle collision without gravity. Where one particle is fixed and another particle is moving with a certain velocity. However, after using the velocity command both particles are still stationary.
Please can someone highlight what mistake I am making?

My input LIGGGHTS script is as follow:

variable dt equal 1e-9
variable m_chamber equal 1.07e-5
variable m_chamber2 equal 1.07e-5

Hi guys

Does anyone know of LIGGGHTS is supported by ARM processors?

Hi everyone,

I simulated the uniaxial compression test using LIGGGHTS-WITH-BONDS by Richti, Is there any source or paper based on which I can help calibrate my model?
Or is there any source for calibrating a model in LIGGGHTS?

Regards,
Tannaz

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