LIGGGHTS® - User Forum

Dear all,

I was looking at the documentation of the hertz model and have a question about the following equation.
K_n = 4/3 Y*(R*delta)^(1/2)

I derived this equation from the hertz model and find the equation should be
K_n = 4/3 Y*R*^(1/2)delta^(3/2)

This result is also given by the wikipedia and some other papers.

Could anyone tell me which one is the correct one? This may have a great influence when the large cohesion is added.

Thanks,
Brian

Hello, everyone!

I have installed LIGGGHTS on our university cluster (CentOS 7.4) with VTK turned off. The compilation was complete and lmp_auto file was created.
I have copied the lmp_auto file to the folder with chute_wear example to check how it is working. However, when I tried
mpirun -np 4 lmp_auto < in.chute_wear
the following error appeared:

Dear all,

Hi, everyone
when I use the rolling_friction epsd3 for my simulation, I got the following error:

ERROR: Could not locate a fix/property storing value(s) for rollingStiffness as requested by rolling_model epsd3. (../modify_liggghts.cpp:411)

The epsd3 model request the definiton of rollingStiffness, but it is calculated as k_r = coeffRollingStiffness*k_n*rmu*rmu*reff*reff in the liggghts doc.

Any suggestion what I missed in my script.

# Material properties required for granular pair styles

Dear LIGGGHTS users,

I recently use rolling frition model epsd for triaxial test simultation. When I create a bulk of particles, and let them settle under gravity, high omega is observed for alomst every particles, up to 500 rad/s. My particles have a radius from 1..10mm.

Can anybody help me with this.

neighbor 0.0005 bin
neigh_modify delay 0

hard_particles yes
# Material properties required for granular pair styles

Hello!

I am doing simulations of powder compaction using artificial gravity. I have been simulating them under 2000g. So once this gravity is applied, particles start to disappear as in the screenshot attached. You can see that number of particles reduced from 7884 to 7508 and then it stays constant. Reducing the time step from 1e-6 to 1e-7 seconds has increased the final number of particles, but only slightly, so some particles are always disappearing.

i am trying to compile Liggghts-public without mpi to define correctly the Makefile.user steps by steps, so I have launch "make auto -e USE_MPI=off -e DEBUG_INFO=yes"
and I got an error where vtkParallelMPI appears! see :

Hi!

Im having trouble with read_data for a model with bonded particles (Schramm/Richti83) using adhesive particles (washino/capillary/viscous).

I cant seem to get the format right in the data-file. Is there a way to check what format my particles have (e.g. ID x y z ...) When I use write_data to create a file I get the following format:

Atoms

1 1 9.0780778811098348e-03 8.4565641784780238e-03 1.9864876941739838e-03 1.8000000000000000e-05 1.0000000000008616e+03 0 0 0

Hello all,

I am using LIGGGHTS version 3.6.0 and CGS units. I am getting this error:
ERROR: youngsModulus <= 1e8 required for CGS units

So I think the unit here is dyn.cm−2 (=0.1 Pa), which means the limitation here is 1e7Pa. Am I understanding it correctly?
If it is yes, then it is not consistent with the youngsModulus limitation in SI units (1e9Pa). So I am wondering why?

Thanks!

Hello, I'm really new to using LIGGGHTS. I find it really hard just to install it as I'm not familiar with the codes given on the installation tutorial. Is there any alternatives on how I can install LIGGGHTS? Thank you very much