LIGGGHTS® - User Forum

Hello,

I have been working with LIGGGHTS for a while now with the goal of setting up a cosimulation interface between LIGGGHTS and another simulation engine (geared more towards multi-physics) . I need to be able to represent complex geometries in the LIGGGHTS simulation with meshes and to get information about forces on that mesh. Does anyone know if there is a good way to get the forces on the vertices of a mesh (either via input script or using the source code)?

Nic

We have a scenario where our python application runs both Lammps and LIGGGHTS in the same process. However, we have a couple of problems doing so. We are trying to patch and fix the LIGGGHTS interface and therefore your help would be appreciated.

Dear liggghts community,

I am studying the granular flow in a hopper like geometry where particles enter the domain at the top and leave it at the bottom at a defined outlet. I would like to be able to control the mass flow rate at the outlet in order to study the flow behaviour at different discharge rates.

My questions therefore are: Is there a way to control the mass flow at the outlet other than changing outlet size? Maybe by deleting particles from a specific area at a certain rate?

Hello,

I am trying to read atoms stored in a dat file by using the command "read_data" but I get the following error:

ERROR on proc 1: Invalid atom type in Atoms section of data file (../atom_vec_sphere.cpp:1066)

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My input file is as follow:

Hi,

I have been dealing with a problem for several days now and I can't seem to be able to fix it.

I need to feed a transfer chute with 278 kg/s. I wrote fix insert/stream 278kg 278kg/s (mass mass rate) and simulate for 1 second. I was expecting to see 278 kg inserted throught my simulation but instead I only got 160 kgs approximately. No matter which values I used I kept getting the same result (WARNING LESS PARTICLES INSERTION THAN EXPECTED). I wanted to know if there is a reason why the sistem only seems to be able to feed a maximum number of particles.

I have been trying to fill a rotating mill volume by the insert/stream command. The commands looks like something below:
fix ins_balls all insert/stream seed 5330 distributiontemplate pdd_feed_balls maxattempt 1000 mass ${mass_of_balls} massrate ${feed_rate_balls} overlapcheck yes vel constant 0. 0. ${downward_velocity} insertion_face ins_face01 extrude_length 0.5


Hello,
I am viewing the LIGGGHTS results in paraview, but I am not understanding how to see the velocity, force, stress changes with time and how to draw the graphs in paraview.

Dear mates,

Dears,

I try to understand fix massflow/mesh command, but it doesn't work with a simple simulation :(
When I run it, the output file (massflow_mesh.dat) doesn't show the correct data, comparing with that I see in Paraview.

I use:
timestep 1e-6
E 5e6
fix mass_u all massflow/mesh mesh cad_base vec_side 0. -1. 0. count once file massflow_mesh.dat screen no writeTime

I attach the data123.tar_.gz with the complete input file (in.liggghts) and the corresponding meshes (stl files).

Regards,

Dear all,
i guess i found a wrong information in the documentation regarding the fix insert/rate/region command.
The corresponding list of general_keywords and their parameters contains the following line:
"once = value to signalise that isertion takes place only once (the step after the fix is issued)"

The value "once", however, is not allowed with this command, as my bash output was:
"'insert_every' = once not allowed"