LIGGGHTS® - User Forum

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.

Dear fellows

Since I am new to ubuntu and liggghts I have problems troubleshooting the attached code after executing make auto in the terminal.
These are my Makefile.user settings:

Hello,

I am a new LIGGGHTS user and during my simulation, I got a strange thing related to no log and dump recorded data at some steps.

The data is suddenly stopped recorded at numerous steps and then it works.

I have checked at several times and got the same phenomenon but in different simulation steps.

Please see attached figures for the details.

I am wondering that does anyone see a similar problem

I appreciate your helps to solve this problem

Thank you in advance.

LTT

Hi I want to perform numerical experiment of a Shear cell test by applying the periodic boundary conditions (as shown in Figure, on a box of 0.0015*0.0015*0.0015m). The aim is to find the friction properties of the particles. The particles are inserted using a factory for 4 seconds (0-4 sec) and then a force of (0.225N) is applied through a top plate for one second (4-5sec). For the next 20 seconds (5-25sec), the force on the top plate is changed to (0.9N) an the shearing action is planned to be induced due to motion of the top plate with a velocity of (1mm/s) in the negative x-direction.

Hi, all,
I am trying to put atoms that meet a certain boolean condition to a group called "inwardatom". This is the code:

variable eatom2 atom "(v_DH>50e-6)&&(v_inOut<0)"
group inwardatom variable eatom2

The error message says:

ERROR: Illegal group command (group.cpp:341)

Can anyone tell me what causes it?

Thanks a lot!