LIGGGHTS® - User Forum

I have been using fix insert/stream to add particles into a simulation through an insertion face. However, the specified particle rate is not obtained if I set a high value of particle rate and a low value for the inflow velocity. I presume the absolute limit of this would be when the spheres are tightly packed, but when I visualise the inlet box using the correct particle size in paraview (glyph), the particles are well spaced out. Can anyone explain what is happening and what is the limiting criteria for correct particle rates to be achieved?

Many thanks!

I'm trying to initialize a simulation with a particle size distribution, created using particledistribution/discrete -> insert/pack, then grown using adapt to increase the volume fraction to 40%. If I try to run the simulation multithreaded, I get MPI faults, and when I run it single threaded I get a segmentation fault. Previously, when using a single particle size, I used the 'scale no' option and had no problems. Has anyone else had trouble with fix adapt 'scale yes'?

I´m new user of LIGGGHTS, I´m working on a simulation that consist in a drum with a little hole at the bottom, and inside the drum a impeller. My goal is see the mixture of material, and the material at the outlet. Nevertheless, the trouble that I have right now is when I import the mesh for the drum and for the impeller I can´t have the impeller inside the drum. I review the documentation, but i don´t have a clear answer.
I attach part of the code i made. I hope someone could help to solve the trouble.
Regards,
CR

Dear all,

Do you know how to obtain the particle collision frequency/number?
maybe in dump command?

Thank you!

Hanqiao

I am running a test simulation (see attached input file) to check energy conservation in liggghts for the case where there is no damping or sliding and only the elastic springs in the normal and tangential direction are active. The damping is set to zero for both normal and tangential contact and the coefficient of friction is set very high to prevent energy loss by sliding. Thus I expect the total energy to remain pretty much constant over time. However the total energy at the end of the simulation is much lower than at the beginning.

Hello,
I am attempting to use the servo command to place a "constant" force onto a bed of particles in the z direction.

I am using the following commands to do so

Hi everyone,

I want to simulate about "roller press" process.
The rollers are load controlled and rotate to transport the particles in plate form.

So,I want to use "fix mesh/surface/stress/servo" and "move/mesh rotate.."

but It does not go well..
（This fix can not be used in conjunction with another fix that manipulates mesh geometry, such as a fix move/mesh・・）

Do you know other ways? Please help me!

Thanks

Why my liggghts (3.8.0) is generating files named such as restart_forced_liggghts_*.data in the simulation directory. I am working on Ubuntu 18.04.
Any specific significance of these files.

I am trying to study superquadric particles in a rotating drum.

I am uploading my input file for reference. I want to write dump information for the two kind of particle templates (cube and sphere) in different files. I want to apply different filters on them during visualisation. I am trying to use group command but it isn't working. Please let me know if there is a tutorial on this or if this is possible.

Thanks,
Apoorva

Dear community!

I use the Fix deform variable command to perform controlled compression process. But when I put in equation current value of pressure I get ERROR: Per-atom virial was not tallied on needed timestep.

Does anybody meet the same problem? Any idea to solve this issues?

Below my script...