I am trying to model a Static screw auger conveyor DEM simulation by importing the obj/stl files for the rigid body components, but it does not seem to be possible. Lammps does not seem to have any meshing capability at all (at least in the most recent stable build: 29Aug2024). So is it possible to import complex geometries into LAMMPS to interact with the particles? The simulation will be quite similar to the granular example which includes simply a rotating drum. Any help would be appreciated here.
At the moment the only option is to import an STL mesh by replacing the triangles with explicit particles using the “create_atoms mesh” command.
This object can be moved by using a rigid body integrator, if the atoms are properly flagged, e.g. using a specific atom type. An example animation for that can be seen here.
Anything beyond that would require you to use LIGGGHTS instead.
Hello, thank you for your response! I have switched over to using LIGGGHTS with some success. I have imported all of my relavent geometry (3 solid bodies, 1 solid body I would like to rotate). However, I am having some trouble simulating the rotating body. The particles seem to not interact with the rotating body at all, and AI tools like GPT are worse than useless in troubleshooting LIGGGHTS coding. Here is the section.
Granular walls
fix bx all mesh/surface file meshes/box.stl type 1
fix bxx all mesh/surface file meshes/auger.stl type 1
fix bxxx all mesh/surface file meshes/drum.stl type 1
Move the drum mesh, rotate around the y-axis (this simulates rotation)
fix movecad_drum all move/mesh mesh bxxx rotate origin 0.0 0.0 0.0 axis 0.0 1.0 0.0 period 250.0
Insertion face
fix inface all mesh/surface file meshes/insertion_face.stl type 1
Granular wall model for the static auger and box
fix wall all wall/gran model hertz tangential history mesh n_meshes 2 meshes bx bxx
fix drum_wall all wall/gran model hertz tangential history mesh n_meshes 1 meshes bxxx
I am trying to import the box and auger as static bodies, and the drum as a rotating body, but no matter what I try the particles do not interact with the rotating body. Any suggestions? any help would be greatly appreciated.
Thanks!
To get help with LIGGGHTS you have to ask in the corresponding forum. This is a forum for LAMMPS.
There is an open pull request to add triangle mesh walls from an STL file: Add granular surfaces built from triangles (3d) or line segments (2d) by sjplimp · Pull Request #4213 · lammps/lammps · GitHub. But it’s hard to predict when that’ll be complete.