LIGGGHTS® - User Forum

Hi,
Can anyone who has used the cohesive model provide some references to realistic values of the cohesive energy density (J/m^3) parameter for some common materials like say wet glass beads or wet sand ?? I know that the value can vary quite a bit based on the amount of wetting and other parameters but it would help to atleast know some ballpark figures.

Thanks,
Tapan

Hello Liggghts Users,

I am new to liggghts and lammps too. I am trying to make changes in the example files (LIGGGHTS) by assigning external electric field using Fix. But I am unable to set charges to the particles using SET command.

The error says : Set command with no atoms existing.

Can somebody explain what I am doing wrong ? or how to assign charges in example file "in.conveyor". (*Sorry for such a stupid question*)

Thanks,

Best Regards,

abhishek

Hi,
Is there a repository from where I can download the previous version of LIGGGHTS (2.0.6) ? I installed version 2.0.7 and I am getting some peculiar results that I was not getting earlier. However before I blame it on the new version I wanted to rerun my code with the older version (2.0.6) to make sure.

Thanks,
Tapan

Hi everybody,

I am trying to install:

• fftw-2.1.5.tar.gz
• openmpi-1.4.5.tar.gz
• liggghts-2.0.6 from git clone from LIGGGHTS-PUBLIC.git

The results are following:

• The installation of FFTW went smoothly.
• The installation of OPENMPI went smoothly too. A simple “hello_world” test gave results as expected, as well as the “mpirun” command.
• The compilation of Liggghts went through without any major problem, except maybe the three lines at first:

Hello Liggghts Users,

I like to use DEM method for charged particles such that they can interact with external electromagnetic field. So I have following questions :

1) Is it possible to define external force field for example Electrostatic force as an analytical expression ?

2) Is it possible to use external field a numerical solution as calculated from other FEM package i.e. field values over a grid of points and use the interpolated field etc. ?

Sincerely,

Abhishek

hi
I have been looking into this last version of liggghts 2.0.6
it seems that compute coord/gran is removed from this last version, of-course it is possible to do this computation manually, with the help of conmpute_pair/gran/local. but it was such a good tool.
thanks anyhow

I'm hoping I'm encountering a common enough fault that someone will be able to help me without even seeing my code. I'm trying to import an STL file from solidworks into a LIGGGHTS script. Basically, I've substituted the mesh.stl file in the meshGran examples for my own file.

Dear all,

For a CFDEM project I tried to model interacting particles in a converging channel, to predict clogging behavior. To realise this I suspect to need cohesion behavior of the suspended phase.
In a 2d situation, also for a pure DEM calculation I get triangle neighbor list problems, even for very small time steps (1e-12) and particle 'explosion'; particles disappear when colliding.

Is cohesion in 2d unobtainable or is something else wrong? Attached my case and stl files.

Particles are quite large in comparison to channel size, just to check the behavior.

Both fix move and fix nve "count" as integrators, and if an atom is under both it will give us this warning. However, what if motion is only partially fixed? Then we still need an nve/nvt/npt integrator, so the warning must be generated.

Even if all DOF are fixed, it would be just a slight waste of time and not a serious accuracy problem.

Hi,

I am trying to simulate rocks that tend not to roll, is there a way that I can model translating only particles?

I tried using the rolling friction model with a high value of rolling friction;

pair_style gran/hertz/history rolling_friction cdt

with

fix m6 all property/global coefficientRollingFriction peratomtypepair 1 0.5