LIGGGHTS® - User Forum

Hello everybody, I'm writing to know if someone has an example of an eccentric funnel flow simulation. My idea is to run a simulation and use the output to create an animation. I could fulfill a cylindrical flat-bottom silo and discharge it through an eccentric outlet, but the result resembles much more a mass flow.

So, I guess the physical properties are not corrected.

Any help are more the appreciated.

Greetings

Hi, all,
I'm trying to analyze powder spreading process of additive manufacturing.
In my case, a cylindrical roller rolls on a bed of deposited powder and spread it to make a new layer on the fusing bed like shown simplified in the attached figure.
My question is how to rotate and translate the roller at the same time.
I have not come up with an idea to move the center of rotation.
Thank you in advance.

Akio

WARNING: time-step is 28.194306 % of rayleigh time (../fix_check_timestep_gran.cpp:200)
WARNING: time-step is 14.155515 % of hertz time (../fix_check_timestep_gran.cpp:208)

I can't help me solving this problem with help of other discussions on forum related to this concern. Can anyone kindly help me with this problem in simpler way..?

I am using lj units to simulate sheared granular flows involving cohesive particles. According to 'LIGGGHTS Documentation', in lj units mass , sigma and epsilon of particle are set to one. In case of chemical bonds, epsilon is depth of the potential well. In case of granular matter what exactly is epsilon ? How do you define this quantity for granular matter ? Can somebody please help me ?? I am stuck here for a long time....

Dear community,
I used LIGGGHTS version 3.7.0 and want to run simple case (free fall by gravity of a single particle) without damping (gamma_n =0 and gamma_t = 0) , but my inputscript below doesn't work (any changes of gamma_n and gamma_t don't affect to movement) .
Can somebody help me with correct writing to change this parameters?

Best , regards Furkhat

#Contact model example

atom_style granular
atom_modify map array
boundary m m m
newton off
communicate single vel yes
units si

Hi everyone,

I have been working on a script for quite a while now and I am unable to print data to a text file.

I am working with two different multi-sphere bodies. I need to know the position, velocity, forces.... on the Centre of Mass and have this data printed in a text file (csv, txt, dat...). For this I am using the next work flow:

1.- Compute command:

#-------Define Compute to Calculate the Properties of Individual Multi-sphere Bodies (clumps)------#

We have downloaded the LIGGGHTS in our Linux server and getting the following error when we run
liggghts < binflow

I'm new to LIGGGHTS and enjoying DEM simulation. I have the following questions.

1. Can I use a cohesion model such as sjkr2 with hertz/stiffness? namely,

fix boxwall all wall/gran model hertz/stiffness tangential history cohesion sjkr2 primitive type 1 xplane 1

is possible?

2. If I use stiffness model with kn, kt, gamman, gammat specified, the values of youngsModulus, poissonsRatio and damping coefficient defined by

fix d1 damp viscous ...

Hello,

I'm running simulation on both LIGGGHTS 3.3.1 and LIGGGHTS 3.8.
When I run a simulation which includes a mesh rotation about 2 axis I get a different rotations.

The command's I'm using are:

fix movemesh1 all move/mesh mesh cad1 rotate origin 0.0 0.0 0.0 axis 0. 0. 1. period 8
fix movemesh2 all move/mesh mesh cad1 rotate origin 0.0 0.0 0.0 axis 0. 1. 0. period 2

Hi Liggghts Forum,

I have a compressed box of particles. The top layer of the particles needs to be moved horizontally in one direction(+y), while the bottom layer in the opposite direction(-y).

I created two groups (edge & edge1) for the particles in the top and the bottom layer respectively. My command for moving the particles are:

fix edge all move linear 0.0 0.08 0.0 units box
fix edge1 all move linear 0.0 -0.08 0.0 units box