LIGGGHTS® - User Forum

Hi,

I am new user of Liggghts and trying to simulation particles in micro units. However, when I insert particle, the fix wall/gran command does not work and the region keeps on increasing with the particle movement.

Can somebody tell me how to overcome this problem?

Thanks,
Subin

Hi,

I want to plant the mesh which have charge on it and interact with particles.
But by fix wall/gran, there is only pair_style for granular is supported.
How can I use another pair_style (e.g lj/coul from LAMMMPS) to fix the wall?

And another question is that when I put the wall by fix wall/gran, sometimes particles are stick to the mesh(wall).
Do you guys know why this happened?

Hi,

I an new to LIGGGHTS and trying to figure out how to create an if loop. I looked at the documentation, but not sure how to proceed.
Here is my current code, not sure if this works.

label shearing1
variable xpos
variable strain_inc equal 0.0
variable max_height equal 0.0377

if ${xpos} < ${max_height}*0.01
#if ${xpos} < ${max_height}*.0025+${strain_inc} then

fix move all move/mesh cad1 linear 1e-04 0.0 0.0
fix move all move botwall linear 1e-04 0.0 0.0

Dear all,

I am using Hertz contact model in my simulation. In hertz contact model tutorial document there has given the normal overlap calculation system but for the calculating the total force I need to take account the tangential force. That's why I need to learn the tangential displacement of the particle. It would be a great help and highly appreciatable if anybody help me to get the calculation of tangential displacement for contact model Hertz. Thanks in advance.

Hi everyone,
I am trying to simulate sintering process of dense packed spheres in a cylinder or a cubic. I've got laws of force between two spheres, but how can I modify the forces between the spheres to apply DEM into my project?
Thank you!

Cheers,
Guo

Dear All,

I am struggling to make start a simulation with high Young's modulus (11.e9 Pa) and small particles (from 100 to 600 microns).
Here part of my code:


atom_style granular
atom_modify map array
communicate single vel yes
boundary m m m
newton off
units si

# When youngsModulus is > 1.e9 use the command 'hard_particles yes'
hard_particles yes

Hello everybody,

as the title says I want to simulate the behavior of a narrow gap couette with granular material, but, to avoid useless calculations, I would like to use the periodic boundary conditions and so I would like to reduce my circular domain to a quarter with periodic boundaries. I saw that there are a lot of posts on this matter but no solutions, have things changed? is it possible to reduce the geometry to a quarter with periodic boundaries?

best regards

Hi Everybody,

I am interested in simulating annular shear with multisphere particles. This system contains a moving rough wall that is made from particles.

For spheres, the moving wall can be set up using a "fix move" command (e.g. fix mv1 wall1 move rotate 0.0 0.0 0.0 0 0 1 1) and the simulation runs well. However the particles in the wall group do not move when the multisphere case is run.

Does the "fix move" command apply to multisphere particles, or is there a more suitable alternative?

Thanks,

Daniel

Hi all. I am currently running simulations of a dry chute avalanche using LIGGGHTS-DEM at various different physical sizes. My test case was using particles with a Gaussian distribution from 0.75-1.95 mm with a timestep of 3.54E-7 seconds, material stiffnesses of 60-200 GPa, and an initial input velocity of 10 m/s during a settlement phase. This settlement phase is necessary for ensuring the right packing of particles in a timely manner.