LIGGGHTS® - User Forum

I could not resolve particle penetration to any walls. What mistake did I make? Below is a code that I worked on. This code will be coupled with the CFDEM.
Thanks in advance for your help.

===
echo both

atom_style granular
atom_modify map array
communicate single vel yes

#boundary f f p
boundary f f f
newton off

units si

region reg block -0.0002 0.0002 -0.0002 0.0002 0 0.0004 units box
create_box 1 reg

neighbor 0.00008 bin
neigh_modify delay 0 binsize 0.00008

#Material properties required for new pair styles

Hi all,

I am trying to run a simulation with a rigid body (using fix rigid). When I output from the fix (using a variables) the x-axis velocity, force, and torque are always almost zero (order e-322). The other output data appears reasonable. Does anyone have any ideas?

Here is a basic example code:

#System Information
boundary f f f
newton off
communicate single vel yes
units si
echo both
neighbor 0.01 bin
neigh_modify delay 0
timestep 5.0e-6

#Atom Information
atom_style granular
atom_modify map array

#Create Atoms

Hi guys,
Has anyone seen this warning before?
"One or more atoms are time integrated more than once"
I use a rigid body (by fix rigid command) to add confining presure to my direct shear test. I have explicitly exclude the atoms of that rigid body when doing the time integration, as suggested in the manual.
For example, I want to integrate a group of atoms excluding the rigid body, I assign:
1. region_1 and group_1 for the atoms I want to integrate
2. region_2 and group_2 for the rigid body I don't want to integrate

Hi

I am trying to apply forces on atoms based on one of their coordinate positions. I have implemented this type of force successfully on a single atom using

run 50000 every 10 "fix acforce all addforce ${Force} NULL NULL region ac"

where

variable Force equal (variable function(v_xposition))

I have introduced additional atoms into the system using

read_data grann

in which I specify their positions, initial velocities, etc

To my understanding I require

Hi

I'd like to set up a simulation for a dense suspension (volfrac: 0.6). To reduce the complexity of the model I'm trying to include the fluid phase with "pair_style lubricate". This pair style is part of the colloid package. And it seems to me, that this package was not installed when I installed LIGGGHTS. Playing around to with the atom_style command I found out that the following atom_styles are missing:
- colloid
- dipole
- ellipsoid
- peri
and my guess is that these packages are not installed.

HI!

I wanted to change the angle of the chute in the after 8000 runs. Therefore I did the following
....
#the chute
fix cad3 all mesh/gran chute.stl 6 1.0 0. 0. 0. 0. 48.3 0.
fix movecad all move/mesh/gran rotate 0. 0. 0. 0. 0. 1. 7.0 cad3
......
fix granwalls all wall/gran/hertz/history 3 0 mesh/gran 5 cad1 cad2 cad3 cad4 cad5
......
fix ins1 nve_group pour/dev mass 3.888 10001 distributiontemplate pdd2 region bc massflowrate 0.5554 vol 0.6 20
......
run 8000 upto
unfix ins1

unfix cad3
unfix movecad
fix cad3_l1 all mesh/gran chute.stl 6 1.0 0. 0. 0. 0. 52.5 0.

Hi everyone,

Are there any commands to see how many particles are in contact with a wall? Or in the code, which part can give a output for the number of particles on a wall? I see the fix mesh/gran command. It can only output the force and torque.

Thanks a lot.

J.Wang

Dear LIGGGHTS users,

Hello,

I am trying to model flow of grains through a slit under confining pressure (imagine sand grains in a fracture confined under a certain pressure). The way I'm doing this is by creating two rigid walls made of atoms arranged in a lattice with a force applied to each atom. However, once I create the lattice and apply the rigid command, all atoms in the lattice are returned with NaN or -NaN in the dump files after the first step. Code is attached.

I know I'm just missing a simple step. Ideas?

Thanks,

Roman

I am trying to run a simulation where particles are poured into a thin, tall container. I had the idea to begin pouring (with insert/rate/region) near the bottom, and move the insertion region vertically as the pile of grains grows. This is so that they won't have to fall all the way from the top of the box to the bottom.

However, when I try to run a simulation like this, it stops after a few insertions. By "stops", I mean it seems to get caught in an infinite loop somewhere. If I pour from a non-moving region, this problem doesn't arise.