LIGGGHTS® - User Forum

Hello everyone,
I was trying to move mesh up and down linearly,

I think somehow I ended up with moving down. My mesh file just goes down and doesn't come up.

I just want little bit of change in position.i.e move mesh little bit up and little bit down while doing simulation.

Right now I am using this command:

`fix move all move/mesh mesh cad linear 0.0 0.0 -1.0`

how can I control mesh while moving down so that it linearly moves up and down?

Thank you.

Hello everyone, I need some help.

Currently, I am doing simulation in LIGGGHTS. My particles insertion area and surface have height approximately 0.02 in si units.

I would like to add some random height so that my particles drop from different height in the same simulations. Purpose of this is to bring noise on heights.

So I want to drop particles randomly at the height of 0.02 +- 10 % or 0.02 +- 20 %while running simulation.

Is it possible to add this idea in liggghts script?

What will be the command?

Thank you.

Hello,

i want to import my particle positions from one Simulation to another. For Testing purposes i'm using the Simulation the particle positions are based on. After the filling process i want to replace the particles with those of the dumb.

I tried doing it with the read_dumb command as follows:

read_dumb dumb.particles_7455000 x y z radius box no purge yes format vtk

When i run it, it says:

ERROR: Unknown command: read_dumb dumb.particles_7455000 x y z radius box no purge yes format vtk (../input.cpp:259)

Hello,

i get the Assertion Error, when i want to simulate on periodic boundary dircetion. If i set all boundaries to fff it works fine. Only when i set ffp, it throws me the error. Can anybody hint me wo where this comes from?

Thanks a lot for your help!

Hello
I am currently using 'LIGGGHTS-flexible fibers'.
My simulation involves several steps, and I create restart files at each step.
I initially defined n_bondtype=2 for my simulations. Later I realized that I have to include one more bond type. To do the same I did the following:

I am using insert/stream for particle insertion. But for some reason, particles do not come out of the region created by specifying extrusion length. And, due to this, I am not getting streaming flow of particles.

Hello Team, I want to specify frictionless primitive wall. I'm having a triclinic box, with particles and primitive walls defined as type 1 and 2, respectively, and important lines in input script are as follows.

boundary p f p

fix m3 all property/global coefficientRestitution peratomtypepair 2 ${EC} 1.0 1.0 1.0
fix m4 all property/global coefficientFriction peratomtypepair 2 ${MU} 0.0 0.0 0.0

Hi
I am using LIGGGHTS-flexible fiber version
I have a step-wise simulation process for which I create several restart files. Later in the simulation, I need to create some atoms, However, I am not able to do that as LIGGGHTS does not allow it.
Is there a way to get around this issue?

Thanks
Shubham

I'm using superquadric particles in my simulation and I want to group the particles having the same sizes after insertion so that each size is put in a certain group how could I code this issue?

Hello everyone!

I want to use hybrid/overlay, and I don't know how to use gran models. When I use:

pair_style hybrid/overlay gran model hertz tangential history

I got:
pair_style hybrid/overlay gran model hertz tangential history colloid 1.54e-4 yukawa/colloid 1.0408e6 1.54e-4
ERROR on proc 0: unknown contact model (.../CFDEM/LIGGGHTS/src/pair_gran_proxy.cpp:82)

Did anyone experience this error in using hybrid/overlay? and how to fix this!

Thanks!