LIGGGHTS® - User Forum

Dear LIGGGHTS users,

I'm wondering how can I fix the walls in the simulation to prevent their movement (not from the beginning, at the certain point of my analysis).

Thank you!
Bee

Hi everyone,

I'm working on a DEM simulation of TRIAXIAL COMPRESSION TEST (Lateral wall under constant pressure, fixed bottom, and strain(velocity) controlled loading at the top) on a cylindrical shaped assembly of particles recently. Some questions bothered me so I'd like to ask for suggestions on how to implement the requirements using existing commands without programming.

Hello
I am currently using Liggghts-flexible fibers. In the bond_gran.cpp file, it calculates the total bond energy using elastic assumptions, and use set bond energy later on.
Actually I am modifying the bond gran.cpp file to include the nonlinear material model, and the formulation with elasic assumptions will not be valid anymore. However I don't need bond energy as an output on my simulation.
I just wanted to clarify, will it affect the simulation accuracy/performance if I keep the bondenergy part erroneous?

Thanks
Shubham

I got two kinds of particles in the .liggghts output. I used 'lpp' and opened in Paraview, but it displayed in the same size.
I tried 3D Glyphs filter with the 'scaling' option. The particles size changed but they are still in the same size.

Hi,
I need to fix the position of some multisphere particles at a specific position in the simulation domain before starting a CFD-DEM simulation. I am having a hard time finding the right command or approach to do this. Is there any way to fix the position of each multisphere particle in the simulation?
Something like the "set" command for single particles in the "twoSphereGlowinskiMPI" tutorial files:
...
atom_type granular
....
# create single partciles
create_atoms 1 single 1.2 0.5 0.5 units box

Hello every body,

I'm new to this DEM field & I'm self learning . I want to simulate particle breakage ( mechanical comminution )- grinding/rolling process in Vertical Roller Mills...So i want to know whether it is possible to simulate this grinding process by applying dynamic motion to imported geometry so that breakage of particle happens..

Thank you

Hi All,

I want to move a mesh on a trajectory. I have the data of the trajectory as a table of time vs velocity or time vs coordinates at every 0.05 seconds. How can I move the mesh in the simulation using the data that I have.

Thanks,

LIGGGHTS (Version LIGGGHTS-PUBLIC 3.8.0, compiled 2023-03-06-18:23:02 by root, git commit unknown)
Created orthogonal box = (-0.02 0 -0.02) to (0.02 0.04 0.08)
3 by 4 by 8 MPI processor grid

Reading STL file 'barrel12.stl' (mesh processing step 1/3)

LIGGGHTS (Version LIGGGHTS-PUBLIC 3.8.0, compiled 2023-03-06-18:23:02 by root, git commit unknown)
Created orthogonal box = (-0.02 0 -0.02) to (0.02 0.04 0.08)
3 by 4 by 8 MPI processor grid

Reading STL file 'barrel12.stl' (mesh processing step 1/3)

Hi All,

I has a liggghts compression code and want to visulaize force chain in paraview. To visulaize force chain, I used these two command lines ("compute_pair_gran_local.cpp" and "dump_local_gran_vtk.cpp").

But I have a issue that force chain cross the simulation domain along x and y direction (see attached pictures). Boundary condition is periodical along x an y direction. There are two walls along z direction. Top wall move down along z direction to create compression.