LIGGGHTS® - User Forum

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

Hi,
If I resize the mesh or change its position in simulation box then LIGGGHTS can not pour particles into box correctly or pour a little particles. Sometimes poured particles have "nan" energy and angular momentum due to resizing. However, I have kept a minimum distance between the wall and the insertion region that is equal to maximum particle radius + half the neighbor skin. What is meant by wall here? wall of mesh or wall of the simulation box?
Thanks...

Ram

Hello!
When I try to use the "fix viscous" command AND the "dump stl" command I get an ERROR: Dump stl can not process all fixes of type mesh/gran, boost nFixMeshGran in dump_stl.cpp and recompile

The same input file without "dump stl" OR without "fix viscous", respectively, works fine.

Christian