LIGGGHTS® - User Forum

Hi everyone,

I was using LIGGGHTS_PFM for a while, and after that, I realized that using LIGGGHTS-WITH-BONDS, based on Potyondy and Cundall's paper, is better for my simulations. I used the same model for an uniaxial compression test, which had no errors in LIGGGHTS_PFM, as input in LIGGGHTS-WITH-BONDS, but it cannot correctly calculate the average stress and strain. Despite the fact that those commands were original LIGGGHTS' commands, not specified only in PFM, can someone help me with this matter? I will attach the parts of the code that LIGGGHTS-WITH-BONDS cannot recognize.

Hi Guys

We are currently using LIGGGHTS to perform DEM analysis on a trouser chute for a bulk materials handling application.
I am familiar with using LIGGGHTS from an academic standpoint and I am able to use the software.

We currently have a test report, please refer to the attached image regarding the contents.
Does anyone have advice for using the test data to calculate input parameters for the DEM simulation?

Hello everyone,

I was using for a project the bond package (LIGGGHTS_FLEXIBLE_FIBERS) and I was trying to write out the number of bonds in a specific region of the domain. Does anybody know how one could do that?

With "thermo_style numbonds" one can print the number of bounds in the whole domain to the screen. However, when i try to assign numbonds keyword to some variable it does not work. It gives a completely different float number. Eventhough it works fine with other thermo_style keywords like "step" for example.

And when i try with:

Hello everyone, I am a beginner in LIGGGHTS. I encountered the following error and hope you can help me resolve it.
The Error is Atom sorting has bin size = 0.0 (../atom.cpp:1438)
I try so many times for the bin size, but it doesnt work.
# LIGGGHTS input script for a ball falling onto sand

# Initialization
units si
atom_style granular

# Create simulation box
boundary f f f
newton off

region box block 0 0.1 0 0.1 0 0.1
create_box 2 box

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