LIGGGHTS® - User Forum

Hoping someone can help because this is driving me nuts! [Maybe solved, see bottom of post]

Sometimes the indenter interacts with the particles as expected, and other times the indenter seems to pass through the particles with no effect. I've been having this problem for some time so I tried to narrow down the cause. I use a workstation running Ubuntu, and a large HPC cluster, and both run the executable compiled with 'make fedora'

I've attached two input scripts (plus associated stl file) in which I'm trying to move an indenter into a box of particles.

Can someone assist with the procedure/steps for importing CAD geometries into LIGGGHTS?

Hi!

Could you tell me a way to dump the overlap statistics for each timestep?

Regards and thanks in advance,

TM

Can anyone help me understand the rotation of shear displacement in LIGGGHTS? The update of shear[0] += vtr1*dt is fine, but I am bit confused with shear[0] -= rsht*deltx. Why has it to rotate and why it is a minus?
Many thanks.

(Problem solved)

Hi All,

I am not sure why, but when I compile the LIGGGHTS 2.0 RC code I have had the fix_wall_gran file replaced with an older version that does not include "unregister_compute_wall_local". Perhaps someone has an idea why this happens. I have posted the error I receive when compiling.

compute_pair_gran_local.cpp: In destructor ‘virtual LAMMPS_NS::ComputePairGranLocal::~ComputePairGranLocal()’:
compute_pair_gran_local.cpp:102:17: error: ‘class LAMMPS_NS::FixWallGran’ has no member named ‘unregister_compute_wall_local’

Hi I've created a simulation where a small fraction of the overall number of particle in the simulation experience a large force relative to the other particle in the simulation. Does anyone know if it is possible to get LIGGGHTS to count the number of particles experiencing a force greater than say fior example 10N? I guess this could be done using a logic statment but i'm not sure how to go about it.

Hello all,

I am generating a txt file for the read_data command and I am getting an error that I just cannot figure out! If someone could be so kind as to take a look at this for me, it would be very much appreciated.

My input file is the following:
##
units si
atom_style hybrid granular molecular
boundary f f f
newton off
communicate single vel yes
read_data read_data.txt
mass * 1.0

###################################
# no boundaries for now...
fix 1 all gravity 9.81 vector 0.0 0.0 -1.0
fix 2 all rigid molecule
neigh_modify exclude molecule all

I am a fresh user of LIGGGHTS just trying to install the program today. I have downloaded the liggghts package via git including the lpp (git clone git://cfdem.git.sourceforge.net/gitroot/cfdem/lpp mylpp) but just can't get any example started after this stage. Do I still need to do a sudo-apt get install before i can get it working? Please help

Hi everybody,

I'd like to calculate the hydrostatic pressure in a cylinder filled with granular particles on its cylindric wall.
I think the command

fix xxx all mesh/gran/stressanalysis xxx.stl ...

is not an appropriate measure to calculate these forces, because by outputting the forces on the mesh with f_xxx[1], f_xxx[2], f_xxx[3] I get the total forces in these directions. That means I get the sum of positive and negative forces and the result will be somewhere near zero...

How could I proceed instead?

Thanks in advance,
kind regards,

Hi, everybody

I'm new liggghts user,
I need to create a planar face for the fix insert/stream but i dont know what are the specifications for making the insertion face