LIGGGHTS® - User Forum

LIGGGHTS® related topics can be discussed here: discussion about models, installation, feature requests and general discussion

Particle sizes in all examples are very tiny

Submitted by yurivict on Mon, 11/05/2018 - 05:30

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

Setting up a DOE

Submitted by mschramm on Mon, 10/29/2018 - 20:33

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

Using fix servo wall to reach a target confining pressure, but failed.

Submitted by Rachel on Mon, 10/29/2018 - 15:16

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.

DUMP stress tensors for each time step in LIGGGHTS

Submitted by astral1000 on Fri, 10/26/2018 - 21:35

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

Confused over response to two mesh/servo loadings

Submitted by pfalkingham on Thu, 10/25/2018 - 11:29

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?

Could not compile VTK example

Submitted by Venkataraman on Wed, 10/24/2018 - 16:14

Hi,

I am new to LIGGGHTS . I tried to create lmp_auto executable, when I run the command make auto the terminal gives me the error "Could not compile VTK example with ...... " Kindly someone help me solve the problem. I downloaded VTK via homebrew on my macOS and gave the path in Makefile.user correctly

My Makefile.user VTK details,

VTK_INC_USR=-I/usr/local/Cellar/vtk/8.1.1_2/include/vtk-8.1
# Path that contains the VTK libraries
VTK_LIB_USR=-L/usr/local/Cellar/vtk/8.1.1_2/lib

What should I do. Please help me.

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