LIGGGHTS® - User Forum

Hi. I have been trying to use six servo-controlled mesh walls to prepare an isotropic sample with a target pressure of 100kPa but encounter an issue that I could not prepare a "stable" sample.

Dear LIGGGHTS users!
I want to use the variable command to include and exclude the specific particles from a group, and I used the similar commands like that in the Docs as following:

compute 1 all pe/atom
compute 2 all reduce sum c_1
thermo_style custom step temp pe c_2
run 0
variable eatom atom "c_1 > -3.0"
group hienergy variable eatom

Dear LIGGGHTS users,

I am simulating packing systems with a very wide range of particle size, and use "neighbor 0.002 multi"+"communicate multi vel yes". However, the output kinetic energy and pressure are both zero. When using "neighbor 0.002 bin"+"communicate single vel yes", the output kinetic energy and pressure are not zero.

Could you please tell me the reason?
Any help will really be appreciated.

Best wishes
June

Apologies for the same issue again.

According to error I know that I have to change my particle insertion region but I couldn't figure it out right region in my simulation. i am totally stuck here.
It would be a great help if anyone could let me to know the idea to fix my error.

Error:

I have been running simple shear stress simulations in LIGGGHTS using moving layers of particles along the top and bottom of the domain to mimic a Lees-Edwards boundary condition. I am able to get reasonable agreement with kinetic theory for normal and shear stresses for spherical particles using the compute stress/atom command. However, when I create spherical superquadric particles to run the same cases, I would expect very close to the same, exact result.

Dear LIGGGHTS users,

I want to relax the packing system statistically by minimizing the energy, and used the command "minimize 1.0e-4 1.0e-6 10000 100000".
The error message is "Minimization could not find thermo_pe compute". The manual explains this error as "This compute is created by the thermo command. It must have been explicitly deleted by a uncompute command". But I have not deleted this compute.

I am trying to run a simple simulation with a mesh file which is available in example as simple_chute.stl.
Now I am able to run simulation after changing the boundary to m m m but all of my particles are falling outside of domain.
Can anyone help me to fix this problem?

This is my script:

###############################################
# Example of LIGGGHTS #
# Flow only two particles in a plane surface #
###############################################

# Initialize

Hello,
I am trying to run a simulation where particles released freely from a height of 700 µm, due to gravitational and contact forces, these released powders freely deposited into the box and formed a powder bed. A roller is then applied to spread a 50 µm high layer of metal particles.
Can anyone share a code for that ? With which tutorials I can start or modify it or which command I should use ?
I am actually a total beginner. I would be glad if anyone can help through with the steps involved in the simulation.
thnx.

Hello,
I am trying to run a simulation where particles released freely from a height of 700 µm, due to gravitational and contact forces, these released powders freely deposited into the box and formed a powder bed. A roller is then applied to spread a 50 µm high layer of metal particles.
Can anyone share a code for that ? With which tutorials I can start or modify it or which command I should use ?
I am actually a total beginner. I would be glad if anyone can help through with the steps involved in the simulation.
thnx.

Hello Everyone!
I am working on the seepage-erosion problem, there is a cube with 0.01*0.01*0.01 simulation box with 6 mesh walls, and two group pariticles with different diameter, called fine and coarse, after consolidation with servo wall, I want to excude the top wall and the group fine particles, I tried to use three kind method which is discribed in documentation as followed: