LIGGGHTS® - User Forum

I am having an issue with particles falling through a wall. Particles begin in a cylinder and are poured directly downward into a block. Most of the particles are caught by the block, but on the first iteration about half of the particles fall through the block when they are first inserted. Is there a reason that these particles fall through? Would the problem have to do with the specified regions or possibly the fix wall/gran/hertz/history?

Thanks
Kirsten

I created a new geometry using AutoCaD and exported it as ASCII stl file. I am using the file in my LIGGGHTs input script. When I run the simulation I get the below error message

Importing STL file 'geometry.stl'
Solid body detected in STL file
End of solid body detected in STL file.
ERROR: STL import failed at triangle #0 (line 1), degenerated triangle?

Can anyone please tell me what this error is about and how to fix this error?

Regards
Vinodh

Hi Christoph,

I am thinking about using the Particle segregation in a slot geometry example for my simulation after doing some changes to it to fit to our simulation.

It will be of great help if you can please share the input script for the Particle segregation in a slot geometry example that is there on the LIGGGHTs website.

Thanks!

Jai

Hi,

I've updated my system using the current version of LIGGGHTS and CFDEM. Compiled both without any problems (using openfoam 2.0.0). Starting liggghts without problems but when the first run command would be started liggghts crashed. The error is looking like:

Setting up run ...
[simserver:25567] *** Process received signal ***
[simserver:25567] Signal: Segmentation fault (11)
[simserver:25567] Signal code: Address not mapped (1)
[simserver:25567] Failing at address: (nil)
[simserver:25567] [ 0] /lib/libpthread.so.0(+0xf8f0) [0x7f519337c8f0]

I am using the latest version of liggght and tried to output the result of the
"comput pair/gran/local pos id force" command with the following dump command :
dump dmp all local 1000 post/dump.force c_10[1] c_10[2] c_10[3] c_10[4] c_10[5] c_10[6] c_10[7] c_10[8] c_10[9] c_10[11]
I can not run the code on more than 1 by 1 by 1 processor grid. as soon as I use 2 by 1 by 1 processor grid or 2 by 2 by 1 processor grid I receive some errors like mpirun noticed that process rank 1 with PID 9127 on node ... exited on signal 11 (Segmentation fault)

Hi,

I want to print the stress or pressure of a single atom into a file. When I put the following lines in the input script, no error occurs:

compute stress all stress/atom
variable xx equal c_stress[1][1]

However, trying to print the xx stress component of atom 1:

fix print all print 100 "${xx}" file xx.txt

results in the following error:

ERROR: Per-atom virial was not tallied on needed timestep

I don't understand this ERROR message even after refering to the LAMMPS documentation.

Best regards
Thomas Wagner.

PS: I found a solution in the forum:

I am pretty new to LIGGGHTS and DEM simulations. I am trying to model granular flow of particles with cohesion force between them. The flow should be like - they start from a point and gather mass progressively in a fan‐like shape as they slide down the slope with some wet/slurry effect between the particles along with cohesion force. I have started looking at the chute wear example by altering the Hertz cohesion coefficient to 1 to have cohesion effect between the particles.

Has anyone done any such kind of simulation using LIGGGHTs before?

Hi,
I encountered an error when doing a simulation based on a modified code of LIGGGHTS which says: Length not sufficient for variable cohesionEnergyDensity. May anybody tell me what problem may it because and in which src document may I find it?

Thanks!

Jerry Wang

Hi,
I created a "particle wall" by using "fix rigid" and tried to let this "particle wall" to compress the particles filled in a cylinder under gravity (so there are totally three materials: filled particles, "particle wall", cylinder wall), but i got very strange result. The "particle wall" pass through the filled particles and even the cylinder (if the timestep is many enough). It appeared that this "particle wall" didn't compress the particles filled in the cylinder at all. Does anyone have any idea about this problem?

Thanks
Xuetao

Hi,
I can not import more than one CAD in new version of LIGGGHT. If I import more than one CAD then it prompts this:

.....
........
Importing STL file 'stl/cyl2p5z.stl'
Solid body detected in STL file
Growing STL input arrays
Growing STL input arrays
End of solid body detected in STL file.
WARNING: STL face normals were not normalized, normalizing
Mesh calculations running. This may take a while...finished!

Import of 14760 triangles completed successfully!

Importing STL file 'stl/spz.stl'
Solid body detected in STL file
End of solid body detected in STL file.