LIGGGHTS® - User Forum

Hi everyone,

I added this command in my file in order to move the top wall:

region topwall plane 1. 1. 1. 0. 0. -1.0 units box vel 0. 0. -0.1

I must define the interactions between the wall and the particles with this command:

fix wall1 all wall/region topwall gran/hooke 1.0 1.0 0.002

But I think that there is an error on the type of interaction (style). How can I define these interactions ?

My second question is: How can I get the normal force applied on the top wall or directly the normal stress ?

Regards
Jf

Hi everyone,

I would like to know, How I can integrate the position of spheres into my simulation ?
I have ready created a sphere packing and I want to use it.

I know that I must add this line into the fle in.mysimulation
# Read data

read_data position.sys

The file position.sys need to be writen like that ? (look the line under)
Please, can you correct ( position.sys) it in order that it works.
Thanks
Regards
Jf

LIGGGHTS Description

1 spheres # number of spheres

T atom types
# type of atom = granular ?

Hi Everyone

I want to make a drum with a horizontal center-line and "fix pour" spheres into it.

1) If I pick the Z-axis for this center line and gravity pointing to -Y, then I get:

"ERROR: Gravity must point in -z to use with fix pour in 3d"

2) OK, so I pick the X-axis for this center line and gravity pointing to -Z, then I get:

"ERROR: Must use a z-axis cylinder with fix pour"

Hi,

i am a newbie to LIGGHTS. Is there any example how to begin with it? Can anyone send me some small example how to start with LIGGGHTS. I have some experiences with PFC but i dont know how to get GUI or how to manage the toll.

Many thanks

cizek.ji@centrum.cz

Hi all,
I have imported two meshes into simulation region. One is base of cylinder and the other is cylindrical wall. I want to find stresses on cylindrical mesh only. But LIGGGHTS dumps all meshes. Is there a same way to group a particular imported mesh and then dump into file?

Thanks in advance,
Ram

Hi everyone,

First congratulation for LIGGGHTS. The installation was easy and the first example (cohesion) runs very well.
I am a beginner in LAMMPS and I'd like to understand a lot of things to build my DEM simulations.

I hope to be able to integrate my developpments (contact laws, …) into LIGGGHTS in order to perform large simulations.

Hello again!

I got an unexpected behavior with the "fix mesh/gran":
Originally I wanted to rotate a plane around the z-axis but nothing happend (F_fl0 in the example). Then I tried to rotate the plane around the y-axis (F_fl2 to F_fl6) but there is an additional (unexpected) rotation around the z-axis ... not what I wanted ...
Workaround would be to change the .stl-file ...
Regards,
Christian

==========
# Example:
atom_style granular
dimension 3
boundary m m m
newton off
communicate single vel yes
units si
region R_gesamt block -0.5 0.5 -0.5 0.5 -0.5 0.5 units box

Hi Christoph,

I was looking at the pour command and had two questions:

1) Is it possible to specify a rate of particle generation? i.e. say I want to create N particles/second. Other than trying to size my region where the particles are to be created to fit this rate, how could I go about this?

Dear all,

I wondered if anyone knows if it is possible to run LIGGHTS on Mac OS X 10.6 using the terminal (downloaded with the developer tools)? If so, could you please let us know step-by-step how you preformed the installation?

I seem to be having problems with the required packages, in particular I am unable to find a version of fftw3-devel which will install on a mac. I am told it is required for the fftw.h header file and I see the program fails after I type "make mac" with the message:

fft3d.h:164:18: error: error fftw.h no such file or directory
make[1]: *** [pppm.d] Error 1

Hi Everybody,

I'm running a larger big simulation (~150k particles) with granular interactions. Most other simulations wotk fine on my system, but this one simulations crash allways after exactly 320000 steps with this errors:

[prometheus:28676] *** Process received signal ***
[prometheus:28676] Signal: Bus error (10)
[prometheus:28676] Signal code: (2)
[prometheus:28676] Failing at address: 0xc
[prometheus:28674] [ 0] 2 libSystem.B.dylib 0x94fe42bb _sigtramp + 43
[prometheus:28674] [ 1] 3 ??? 0xffffffff 0x0 + 4294967295