LIGGGHTS® - User Forum

Hello,

I'm new in LIGGGHTS and would like to have a look at the input skript of "Particle segregation in a slot geometry".
Where can I obtain it, because I think it doesn't exist in the normal examples-folder, does it?

Cheers

I've done a simulation with three thousand granular particles in a container with a blade stirring them around. See video on the URL below:
https://docs.google.com/leaf?id=0B2EIcnb16wvuZWRmZWRiYTktMGQ4OS00OWMzLTk...

If you look closely, you see that some of the particle's got a "popping" behaviour, it's like small explosions shooting away some of the particles. What am I doing wrong?

Dear Liggghts users,

I have difficulties in defining an additional force due to a couette flow. Therefor I want to add a force depending on the atom position. I define a per atom variable "b" and I want to refer to it as "v_b" in the fix addforce.

I guess I didn't got the idea how to use per atom variables within fixes like addforce.
I attached a simple input file in which I summarized, what I have already tried.

Maybe someone can show me a working example of an addforce/setforce fix with per atom force values.

With kind regards,
Thomas Wagner.

Hi,

I would like to calculate each particle kinetic energy, potential energy (gravity) and rotational energy to total energy

please give me advice.

Dump file is x y z ... but I have to calulate them or just after simulation

extra term kinetic, rotational, potential (gravity) and total (each)

Thank you

Hi,
I'm trying to set a volume filled with particles to use and re-use after.
My questions are:
1) What is the faster insertion method to fill a volume until the level I want?
I'm trying with ins pour/dev but I have to wait for the filling (and some time I have less insertion than wanted); with lattice I have to wait the KinEn decrease (and it doesn't respect the level I want). pour/dev/packing could help me?

Hi,
Is there a way to erase all previously forces on CAD mesh before dumping new forces on it due to granular particles?
Thanks,
Ram

I am running LIGGGHTS with approximately 34,000 particles in a confined STL geometry with mixing paddles rotating to agitate the particles. I've noticed in my output (as .vtk files) that the order in which the particle positions are written change every 1000 time steps (regardless of how often I dump data). The "Lookup Table" for atom types at the end of the .vtk file changes correspondingly. Thus, if I have two atom types, visually the simulation runs smoothly.

Hi all,

I have identified a bug with LIGGGHTS, which is causing problems every time a run command is encountered in the input script. What I have seen is that the run command deletes all the forces and recalculates them, and I think that something is not done properly in the way the shear force gets calculated (ie in the way the last value of shear gets passed on to the pairs at the initial step after run Nsteps is found).

Hello, Christoph, i simulated a compression test, after compression, i want to remove the top plane. As i understand, it could be done by using unfix wall and i used unfix wall/gran/hertz/history, but i got 'Segmentation fault', could you help me? By the way, i used the latest version of LIGGGHTS.

P.S. I have read few similar discussions in the forums. Based on these discussions, the bug should be fixed, so i don't know if something i did wrong.

thanks,

Ada

Hi,
How can I define material properties of 3 types of particles? As, I want to use different friction between particle-particle(0.1), particle-bottom wall(0.0) and particle-side walls(0.7). Is this correct way of defining:

fix id all property/global coefficientFriction peratomtypepair 3 0.1 0.0 0.7 0.7 0.7 0.0 0.0 0.7

thanks,
Ram