LIGGGHTS® - User Forum

Hi all,

Hi everyone,

I'm using the LIGGGHTS-WITH-BONDS package that was proposed by richti83. It works great even in CFDEM! However if I use periodic boundary all particles that exceed the boundary and reappear on the other side of my geometry lose all their bonds and are calculated as single unbounded particles from there on.
Am I doing something wrong or is it just a limitation of the current model?
Any suggestions or experiences?
Thx and regards

Hello to all of you

I have recently simulated the multisphere example that LIGGGHTS bring in the "examples" folder. After the post process, i use Paraview (version 4.1), but when i opened the VTK file, this error appears:

ERROR: In /build/buildd/paraview-4.1.0+dfsg+1/VTK/IO/Legacy/vtkDataReader.cxx, line 1919
vtkPolyDataReader (0x3518b50): Unsupported data type: 1

I think this is because of the version of Paraview, so my questions is, what version of Paraview support multispheres?

Thanks

Nicolás.

I am using the liggghts-with-bonds package to create bonds as described by cundall.
I can't find the syntax for fix bond_coeff
I copied the command somewhere and it works but i would like to understand what the arguments are in order to modify them. It seems that the second argument is the particle diameter which doesn't make any sense to me, because cundall always uses the smaller of both radiuses and I even found that command in the source code.

Hello,
I am seeing a problem when running a restart file.
The past simulation I had used a plunger to compress particles in my geometry.
I am now reading in my restart file and swapping to a different size plunger.
When I use the fix mesh/surface/stress command and state that I would like to
position the plunger at x,y,z, liggghts' positions it at 0 0 0..... I am stumped on
what could be causing this. I tried moving the file outside of my domain and
liggghts recognized that I did this but during the run, the mesh is back to 0 0 0.

Hi,
I have a problem with multisphere particles simulation.
when i use same case for simple spherical particles mixing, my results are good but when i used multisphere particles ( 2 or more sphere clumped together to form particle) then particles becomes cohesive and no mixing occurs between particles. i created multisphere particles according to code given in following link
https://www.cfdem.com/media/DEM/docu/fix_particletemplate_multisphere.html

Very new to LIGGGHTS. Tried to set up my first simulation: particle dumping from a cone into a cylinder. I see this error:

Hello,
I was going through the source code and came across this function, and I was looking to see if there was any more information on it.
I was able to get it to work and it does what I have been using MATLAB to do.
I am working with the bond/gran model and have been using MATLAB to spawn in my fibers.
However, the fix_template_multiplesphere function is doing (almost) what I want.
I say almost because it seems that the code is only checking if "starting node" of this template is inside the boundary

Hello people. I made another thread in developer forum, asking how to get the force in a simulation using granular bonds. The problem is that the values shown in dump files, aswell as the values calculated with compute property/local are way low than they should be (for the example i uploaded it should be around 31N, and its showing in both cases something close to 1e-6).

I tried running the simulation at 64, 128 and 256 cores, with the same in file and the executable. The simulation works fine for 64 cores but when we run it on 128 and 256, the particles seem to fly out or seem to be get deleted somehow.
I hope someone could give me an insight about this.

I have attached the in file, the only difference between the 3 being the number of processors.
64 cores -processors 16 2 2
128 cores -processors 32 2 2
256 cores -processors 64 2 2

Also attached is the final image of the simulation.