LIGGGHTS® - User Forum

Hi all,
I know in LIGGGHTS 1 tria is like 11 particles, but I'm wondering if in LIGGGHTS there is a maximum number of Tria Elements or a Correlation between tria/particle size.
This because I run a case with particles size R=8-12 mm with a moving stl (num. elements = 36720, size = 2-5 mm) and when stl starts to touch particles it crashes with seg. fault!
(If I use a coarse / interm. stl mesh it works fine).

Another question regarding stl. Where is evaluated the momentum (Nm) on stl? Around the origin (0 0 0)? Is it possible to give to LIGGGHTS a different center of rotation?

Thanks

Hello everybody,

I'm a little bit confused about the doc of the fix property/global.

In the example the style-arg for atomtypepair "nCol" is set to 2 and the number of defaultvalues is 6, which are mapped into a matrix like
[1 2
3 4
5 6]

dear all,
I want to do a particle mixing test.
Is there any method that I can use to mark different particle groups, all the particle groups have the same material parameters, such as young modulus..possion rate...thermalconductivity and so on, the only difference is the label. (group 1, group 2.....)
For example, after all the particles accumulate in the bottom of the container, the upper half region was settled with label 1, and the lower group with label 2.
is it possible to deal this problem as similar to the temperature setting. the set command was used following a region command.

Hallo everybody,

while trying to build a quite simple simulation (basically some granular particles inserted in a cylindrical box) i get multiple warning messages: "Dangerous build in triangle neighbor list" when executing my simulation.

These warnings don't appear right at the beginning of simulation, but at a quite early stage.

Visualised in ParaView, it looks like this:

Hi,

Is it possible to define specific frictionless walls? (while certain walls and the particles among themselves have friction)

Thanks!

Hi there,

I want to achieve a certain packing factor within a given region in my granular bulk material.

I tried to achieve a packing factor of 0.6 (Volume of solid material within the refered region / volume of refered region) within the region reg_ins by using this fix:

fix ins all insert/pack seed 100001 distributiontemplate pdd1 insert_every 1000 overlapcheck yes all_in yes volumefraction_region 0.6 region reg_ins ntry_mc 1000

What happens in the simulation is:

Hi all,

I'm working on a simulation where I just want to investigate the behavior of non-spherical particles during filling and emptying of a small container. I want to clump multiple spheres together to form elongated particles. For a few individual particles, I have done it already with fix rigid. This is quite expensive for several 1000 particles. What I want is to fill the domain with a continuous stream as in the example on this website (node/20).

Hello all!

I am trying to add a brand new stl file for use as a granular wall in a restarted simulation with mesh/gran/stressanalysis etc.. When the simulation runs, the KE is as expected but the all the stress values in the vtk dump file are 'nan' even though the imported gran wall is nowhere near the very few particles in the system. What to do? I suppose I could start a new sim using old particle position data instead of restart, but I would much rather restart

Hi all LIGGGHTS uesrs and developers

Does LIGGGHTS 1.5.2 support non-spherical granular simulation?
And if does, how to do a simulation with non-spherical granular?
May someone provide a simple example with input files?

Appreciate any help in advance!

If I have a cylindrical container created like this:
fix zwalls all wall/gran/hertz/history 1 0 zplane 0 0.3 1
fix cylinder_wall all wall/gran/hertz/history 1 0 zcylinder 0.052 1

should I expect the same effect on the particles if I wiggle the "region" than If I wiggling the two fixes written above with the same amplitude and period?