LIGGGHTS® - User Forum

Hello all.
I want to simulate a granular flow behind a gate and after a time the gate have been released (like a dam break).
I could not insert particle once... could any body help me? The total mass is 0.8 kg and particles radius is 0.8 mm.
atom_style granular
atom_modify map array
boundary m m m
newton off

communicate single vel yes

units si

region reg block -0.5 0.5 -0.2 0.2 -0.2 0.35 units box
create_box 1 reg

neighbor 0.01 bin
neigh_modify delay 0

#Material properties required for new pair styles

Hi,

I have a problem when trying to model atoms which are 100um in diameter. When the atom size is 100um in diameter, the atoms keep lost during the process, and it won't happen when atom size is larger than 0.001m. Could anyone explain why it happen and how to fix it? I tried to change the units to cgs, but it did not work...

atom_style granular
atom_modify map array
boundary f f f
newton off

communicate single vel yes

units si

region reg block -0.05 0.05 -0.05 0.05 0. 0.15 units box
create_box 1 reg

Hello everyone:
My quetion is that if i want to simulate granular materials,how should i choose the binsize? the manual says default value is 1/2 cutoff.
Does it mean the binsize for granular is 1/2 rmax+1/2 skin?

I've created the FreeBSD port for liggghts. However, all examples run with sizeless particles.
For example, the conveyer example doesn't look like the youtube video https://www.youtube.com/watch?v=DJ-d5WjVYz8. All particles look like white dots of 1px size. And also there's no plane that particles fall on to.

I use ParaView to display *.vtk files.

What is wrong with my installation?

Version: 3.8.0
vtk8-8.1.1
paraview-5.5.1

Hello,
I have been making DOEs by utilizing the universe variable type

variable var1 universe 1 2 3 4 5
variable var2 universe 0.1 0.2 0.3 0.4 0.5

# DO THINGS WITH var1 and var2

next var1 var2
clear
jump in.liggghts

Is there a way to use the file variable type to read in all of my DOE values from a txt file?

I have tried
variable var1 file vat1_vals.txt
variable var2 file vat2_vals.txt

but when I call

mpirun -n 4 liggghts -in in.liggghts -partition 4x1

Hallo,

unfortunately I do not know how to give different colors to different atom types. Maybe someone can help me. Thank you.

Sincerely yours

Emanuel

Hi all,

I am using LIGGGHTS for a confining process of a cube area. The maximum and minimum of particles are 5mm and 1mm, respectively. Here I use six servo wall to confine the particles, e.g.

fix topwall all mesh/surface/stress/servo file meshes/topwall.stl type 1 com 0. 0. 0.1 ctrlPV force axis 0. 0. -1. target_val ${targetForce} vel_max 20 kp 0.005

I keep updating the value of "targetForce" so as to reach a confining pressure of 50kPa, but I found it very hard even after 5,000,000 step with timestep=2e-7.

Hello, Everybody

I have a problem with dumping stress for my shear stress simulation. Whenever I try dump pxy pressure component I get an error of Illegal thermo_style keyword (when I put pxy into thermo_style) or Illegal variable command (when I use pxy in the variable command)

Could you please help me dump stress components for each timestep?

atom_style granular
atom_modify map array
boundary m m m
newton off

communicate single vel yes

units si

region reg block 0 0.086 0 0.086 0. 0.085 units box
create_box 1 reg

Apologies if this has been covered elsewhere, I did do a search of the forums first.

I've got a test scenario where I'm compressing a particle bed with a servo-controlled mesh. I've run it at targetVal 5 and targetVal 50, but the results are quite different:

https://youtu.be/EBcXjh_FZ9A

I expected targetVal 50 to be similar to the sim on the left, but with forces 10x greater. As you can see, I'm not even getting forces oriented normal to the compressing plate.

Is this normal? Am I doing something silly somewhere?

hello,