LIGGGHTS® - User Forum

Hi guys,

I need to create walls using mesh/gran command and wonder how to create these walls through stl from CAD?

Many thanks

Hi guys,

Base on the example of in.packing, I am trying to do a packing similarly.
Different from the example, I use pair style of gran/hooke/history/stiffness instead. I don't think it would be problematic but the system crash down when it came to the nve integration,
Here is the output of the screen:

LIGGGHTS 1.4.4 based on lammps-10Mar10
Created orthogonal box = (-1 -1 -1) to (2 2 2)
1 by 1 by 1 processor grid
0 atoms in group upper
0 atoms in group lower
0 atoms in group total

I created ideal walls and want to use the fix wall/gran/hertz/history/stiffness command and the syntax of this command is:

fix ID group-ID wall/gran/(*) friction_damp_flag cohesionflag wallstyle args keyword values ...

I don't really understand the group-ID here, does it mean the ID of the group that I want to create walls to bound? or the ID for the group of the walls themselves? How to "group" these walls? they don't consist of particles.

Noob question.
I would like to simulate particles falling down in a container filled with water. For now I do not need to couple with CFD, but I would like to able to tell the simulation that once the particles reach a given region, they are subject to an Archimedean lift.
But I am not sure how I can do it? Any simple example that I may have missed?
Thanks!

Hi guys,

I am trying to simulate a Direct Shear Box Test for soil.

I want to create two containers (two granular boxes, upper & lower) to contain the soil assemble and do the shearing.

To create the containers, I am thinking of wall/gran, however, I don't know how to group this walls together so that they become a container and move together, be able to read the force on it.

Please help me out if you have any thoughts or did something similar.

Hi there,

Can someone comment on one of the results in Benchmark 3 where the speed of LIGGGHTS is slower than the commercial code for the continuous blending mixer case? Why is it slower in this test case?

Also, which commercial code is it? Can you please email/message me privately? I'm doing some benchmark myself too.

Thanks,
Sam

hi

I am not able to use atom style ellipsoid for my simulation. I have done work using liggghts with granular atom style and had no problems. But when i try to use ellipsoid atom style, it gives an error saying "invalid atom style". Same goes for colloid and dipole atom styles as well. Here's my input file
atom_style ellipsoid
boundary f f f
newton off
atom_modify sort 0 0

communicate single vel yes
units si

region reg cylinder y 0 0 0.0225 0 .08 units box

create_box 2 reg

neighbor 0.001 bin
neigh_modify delay 0

shape 1 1.0 1.0 1.0
shape 2 1.0 4.0 1.0

Hi all,
I have performed DEM simulation of radial segregation in horizontal rotating drum. Results are in good agreement. Publication is being accepted. Watch simulation video:

https://www.facebook.com/photo.php?v=3090292932292

Shortly, all input files and tutorials will be posted here.
Thanks,
Ram

Hi guys!

I am currently learning LIGGGHTS to simulate the Direct Shear Box Test for soil and thinking about the Granular package.
Under the pair_style gran/hertz/history/stiffness command, I am able to define the stiffnesses of soft contact and damping constants etc,
however, I also want to define the internal friction angle of particles to describe the particle-particle friction coefficient.

Anyone can help me out on that?

Dear LIGGGHTS-Users,

I try to simulate a simple water jet that impacts on a wall. Does someone know how to generate a continuous water jet with the sph-model. I know how it works with the "insert/stream" command for a granular simulation but it seems that this is not valid for sph.

Thanks for any reply
Nate