LIGGGHTS® - User Forum

Hi,

Hello,

I'm starting a project, aiming to determine the shear forces on a conveyor belt. I have a geometry .igs and .dwg; How do I import these in a way the Liggghts recognize?

And how do I tell Liggghts that I want to calculate the force on the belt, after the particles come out of a chute?

It's my first work.

Hi All,

is there an easy way to implement a spherical particle, which has a high young's modulus on one halfspace and a small on the other halfspace (such as a Janus particle)? For example, could I define a point on the particle's surface, which follows the particle's streamline and the angular velocity?

Thanks for help.

Johannes

Hi,

I have been looking around with possible packages that could be applicable for my problem. After hours of google-fu, I arrived at LAMMPS and eventually here. Hence, I want to know if it could be possible to achieve what I am looking for with CFDEM.

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: