LIGGGHTS® - User Forum

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.

As is has been discussed in the previous topic (https://www.cfdem.com/forums/radiation-model-can-be-added-packed-bed)
My new paper on the paritcle thermal radiation is published in the Journal of Heat Transfer (ASME),the titile is "Modelling effective thermal conductivity (ETC) of thermal radiation for nuclear packed pebble beds",

Dear wall,

I am facing a problem about removing particles in the process of simulation. In my model, the particles are moving inside six stl. mesh walls, if they get in contact with the stl walls, the soil particles should be removed. To help understand, I also draw a picture of my problem.

I don't know which command should I use if I want to remove these soil particles under some certain criterion. Could you help me? Any suggestions would be of great appreciated.

Best regards,
Zheng

Dear all,

I am now using command "move mesh" to move stl walls, the velocity of the wall will change with the time, shown as the variable "v_vyl".

fix leftwall all mesh/surface/stress file meshes/leftwall.stl type 2
fix moveleft all move/mesh mesh leftwall linear/variable v_zero v_vyl v_zero

Hello every LIGGGHTS users and developers,

I am currently using the version of 3.7.0 and expecting the information by the fix contactproperty/atom/wall could generated as an output file.

I tried conventional methods such as:

1. dump local (ERROR: Dump local fix does not compute local info)

2. dump custom(ERROR: Dump custom fix does not compute per-atom info )

Therefore, I really want to know that whether I could have access to the information by this command and how I could be able to acquire it.