LIGGGHTS® - User Forum

Hello friends,

I am trying to use the mesh/tet command and so far I had no success.

I used 2 meshes in the study. The first mesh is a STL mesh. The second is a VTK mesh. Both meshes are in the same scale (mm). I scaled the meshes by 1e-3, because the unit system of the study is SI. If I run a test without the VTK mesh, everthing run ok. But if I run the study with the VTK mesh, liggghts return this error:

ERROR: VTK mesh file is incompatible with simulation box: One or more vertices outside simulation box (input_mesh_tet.cpp:298)

Hi

I'm trying to do a simulation with materials of different diameters (two materials). But I'm facing the following error:

"ERROR: Fix property/global (id m3): per-atomtype property matrix must be symmetric, i.e. N atom types require you to define N columns and N rows with N*N total values (../fix_property_global.cpp:158)"

In my settings are:

fix m3 all property/global coefficientRestitution peratomtypepair 2 0.8 0.8 0.8 0.8
fix m4 all property/global coefficientFriction peratomtypepair 2 0.15 0.15 0.15 0.15

Hi,

I can already count total number of contacts as richti83 suggested here: https://www.cfdem.com/forums/particle-contacts-using-contactatom

I'm interested in counting collisions only between atoms of different types (types 1 and 2). Is it possible?

Hello everyone,
I think, the references at the documentation of "gran model hertz model" are not correct.

I spent a whole day to have a look at the references, before using them at my thesis.
I discovered, that the references are containing similar models, but no one of them, uses this model.

More over, there are some questionable things at the documentation like the bullet point
rmu = coefficient of rolling friction

But rmu is no where to be found ...

Hi everyone,

I am managing to implement the mesh/stress/servo command in my simulation. In my case, I would like to use the command to compress a packing by a small vertical force, i.e. I just want to flatten the top surface of the packing rather than strongly compress it. In other words, I just want to use a small force to compress the packing, thus I use CtrlPV force and target_val 0.003 as the parameters.

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