LIGGGHTS® - User Forum

Hi all, I am currently trying to run a LIGGGHTS script of granular particles sliding down a chute. I have tested the code with a monodisperse size distribution and now want to match the size distribution given for a specific sand that I'm using in my experiments. My understanding is that I should be able to use the following code to produce a distribution with 3 different particle sizes:

I am newer to LIGGGHTS so I am still learning my way around assigning properties to particles. In my simulations the particles are spheres, and they are in a packed bed. Over time the particle's properties need to change based upon their position, in particular radius, Youngs Modulus and Poissons ratio. I am using the granular hertzian pair style without history.

All the particles are inserted in the first step, but I want to make these particles flow from the inlets step by step. I don't know what the problem is , here is my input commands, pls help me , thx~

Inputs:
"
....
neighbor 0.004 bin
neigh_modify delay 0 one 20000 page 500000
....ere the input

Hi,

I am wondering if there is a way to extract each individual contact force acting on a sphere clump (a multisphere)? I know there is a method called pair/gran/local that is able to get per-sphere contact forces. However this command does not offer an option indicating the id_multisphere that each specific sphere belongs to and computing stress through contact force and branch vector can be very difficult since we need identify the center of mass coordinates of two multisphere bodies that are in contact. Any suggestion is greatly appreciated!

Best,
Liuchi

Hello,

My objective was to calculate coordination number for each atom in a system having two atom types. I wanted to calculate the coordination number for same type atom contacts for both groups and different type atom contacts also.

I have used the following compute:

compute 1 all coord/atom along with the "mix - yes or no" option to get selective outputs for coordination number by contacts between atoms of different types.

All,

When I am trying to compile LIGGGHTS with Makefile.g++VTK (as attached) then I am getting following error:
Please note it compiles finely without -DLAMMPS_VTK switch.

make[1]: Entering directory `/lustre/scratch/rsoni/LIGGGHTS/LIGGGHTS-PUBLIC-350-VTK/src/Obj_g++VTK'
g++ -g -O -DMPI_NO_CPPBIND -DLAMMPS_GZIP -DLAMMPS_JPEG -DLAMMPS_PNG -DLAMMPS_VTK -DMPICH_SKIP_MPICXX -DFFT_SCSL -l/usr/include/ -c ../dump_atom_vtk.cpp
../dump_atom_vtk.cpp:47:24: fatal error: vtkVersion.h: No such file or directory
#include


Hello,

I've built LIGGGHTS with the sphere package but have problem defining the pair_style between them. I checked the online documentation that the hertz contact requires torque and angular velocity given by atom_style and also per-atom radius, which I have no idea how to define for ellipsoid. I have not tried the hooke one yet but from the documentation I think it also only works for spherical particles. Any suggestion is greatly appreciated!

Thanks,
Liuchi

There should be three vtk files when I open paraview, but after trying to install CFDEM, only one exists now. When I run the test-case, I can't see particles now.

Hi

I'm new using LIGGGHTS.
I'd like to simulate a sand glass with LIGGGHTS. It works quite good for now, but i need a usable value for my sand's friction.

fix m4 all property/global coefficientFriction peratomtypepair 1 ??

If i had a Ra value, would it be possible to assess or even to compute the friction of my sand? (see the SEM picture)
Or has someone experience in simulating sand and knows a usable value?

something else: