LIGGGHTS® - User Forum

Hi everybody,
I could not find anything about this in the forum yet, so maybe I missed it. But I have experienced something weird lately.
When I run the same simulation on 1 or 2 CPU I get different results. And by different I mean slightly different in the trajectory and the forces.
You can check this with the tutorial movingMeshGran. It does not matter how often you run it on a single core, the result is always the same (checked with diff on the dump files, no difference). As soon as I start a parallel run they differ. And not only this, 2 CPU differ from 4 CPU usw..

Hi everyone,

I have a question about number of bins and bin size when using neighbor bin command.
I have read some post regarding to Too many neighbor bins, and it seems that LIGGGHTS limit the number of bins to 200. I tried to figure out how to estimate the number of bins.

number of bins = half size of simulation domain(in xyz direction)/bin size, is this correct?

the optimal bin size is 2*max radius or 4*max radius?
because I find tow posts discussing this setting.

Thanks
Weijing

A beginner here. Successfully cloned LIGGGHTS 3.6.
Successfully made and build VTK 7.1.1 using CMake and VS2010.
No issue in making LIGGGHTS 3.6 with CMake. However, building in VS2010 shows 157 errors!!

It would be so so great, if anyone has recently installed LIGGGHTS on any windows platform (preferably Win 7) using Visual Studio (preferably 2010) and can give some help.

Hi

Can someone assist me on how I can insert particles into a fixed volume so that I achieve a desired bulk density. Are there any insertion related variables that I can play around with?

Regards

I think this is issue is related to the previous post by Zhenli, but I don't want to hijack that forum post with my own issue. I am trying to simulate a direct shear test with mesh walls and 11700 multisphere particles (log file attached). The multisphere particles are actually spherical consisting of one sphere of smaller diameter within another sphere since multisphere templates of only one sphere are not allowed. The simulation runs to completion without an error being thrown, but partway through the simulation the total number of particles suddenly drops.

Dear all,

I am just by testing the multisphere method in LIGGGHTS3.6.0. The case was very simple, the multisphere particle consists only two particles.
some thousands of multispheres were simulated. A moving stl wall was available in the simulation.
What I found was, the single simulation went no problem, but the parallel simulation has a "explosion" of particles after 3-5 timesteps first at the boundary of each sub-domain.

Is this problem known and are there some methods to overcome this problem?

Thanks a lot!

best regards

Zhen

Dear All, I've running binflow simulation available at LIGGGHTS Tutorial and couldn't understand the meaning of insert_every option of insert/rate/region fix.

I have to run a few simulations quite similar to this one implemented in the binflow example, and then went through the input file reviewing the documentation of each command used (by the way, this and other examples are very illustrative, congratulations).

This is the command I have in the input file:

Has the "info" command been removed? I keep getting errors saying unknown command whenever I try to call this, even when I just use the examples for this command shown in the documentation.

Well, this is a basic test.
But, it does not work.
Here is the in file:

#particle distributions and insertion
fix pts1 all particletemplate/sphere 15485863 atom_type 1 density constant 8000 radius constant 0.005
fix pts2 all particletemplate/sphere 15485867 atom_type 1 density constant 8000 radius constant 0.0025
fix pts3 all particletemplate/sphere 15485867 atom_type 1 density constant 8000 radius constant 0.001

fix pdd1 all particledistribution/discrete/numberbased 32452843 3 pts1 0.3 pts2 0.5 pts3 0.2

Hi all,

I have some problems when trying to set a following symbolic link for LIGGGHTS as mentioned in the installation guideline. After running the "make fedora" command, I got "Obj_fedora" as a return in the /Home/LIGGGHTS-PUBLIC/src directory instead of "lmp_fedora. Can anyone help me with this? Appreciated for your help.