LIGGGHTS® - User Forum

Hi!

I need to calculate the numbers of contacts between particles and walls, something similar to compute contact/atom, so i tried to determine the overlap on the mesh. My question is what´s the difference between compute wall/gran delta (overlap of the contact) and fix wall/gran contact_area overlap?.

For compute wall/gran delta, i got just one column of data, but for fix wall/gran contact_area overlap, i have 8 columns of diferents information depending on how many f_Id[x] i define.

Where can i check which information f_id[x] is showing?

Hi All,

In my work I have to do stress analysis for particles in domain(there is no stl file). With stress/atom and compute reduce I have some doubts, however I have gone through previous discussions on stress analysis. stress/atom generates a vector and we can access its elements like c_stress[1] to c_stress[6]. Now as explained in user document :

I want to insert particle in lattice. But I have found that I can create atoms in lattice via create_atoms command but I have not found any tutorial how to insert particle in lattice. Is atoms and particles behave same in liggghts? Any help is highly appreciated. Thanks

Hi all!

I´m trying to store the forces between particles-wall colision but when i add this line "fix granwalls all wall/gran model hertz tangential history mesh n_meshes 1 meshes cad1 store_force_contact yes" to my scritpt, i get the following message error:

Invalid fix style: "contactproperty/atom/wall" (../modify.cpp:820)

I´m using Version LIGGGHTS-PUBLIC 3.3.0. Im not sure if that its the problem, so I tried to upgrade LIGGGHTS to a recent version but when i use "make clean-all" ----> "make fedora" i get the following message error:

Hi all,

I have tried to create meshes from gmsh. When I am trying to import to my liggghts script and run it, an error occurs saying "ERROR on proc 0: Bad registration of upcoming move. (../mesh_module_stress_servo.cpp:252)".

How can I solve this problem?

Hi all,

I aim to insert 8000 particles with same radius into a 100mm*100*100 cubic box. When I am trying to view the result in paraview, I have selected the 'radius' option from paraview to check the particles size. The result shows that the particles radius is changing throughout the timesteps. Can anyone help with this? Thanks.

# First Trial for model stimulation (real)

# Initialization

# Preliminaries

atom_style granular
atom_modify map array
boundary f f f
newton off
echo both

Hello,
I'm struggling to understand what is wrong with my simulation since I specify a particle size distribution in the input file which is not reflected in the output file.

Can anyone help me please? Basically it looks like I get a shift of the mean value of the PSD toward higher values in the output file.
It seems that this might be related to missing of the smallest particles in the output file? Not sure why they are not there as checking the log file all the particles seem to be inserted.

See below input file

Hi all,

Does any know why my particles are floating after inserting? I would like my particles to sink/settle to the bottom without floating. I have attached with my script. Thanks in advance.

Hi all,

I wish to insert particle into a 100*100*100 cubic. I would like to form the figure as attached with particles are settled under gravity and align with each other. (the one with blue particles) However, I couldn't able to form it and particles distribution are not similar to a cubic shape. (the one with grey particles) I have attached the figures and my script. Thanks for the help.

I am using liggghts-with-bonds and trying to perform an indentation. Unfortunatly the bonds suddenly break shortly after they are created(5519 bonds are created at timestep 50000 and they suddenly disappear after timestep 52500). They are not even under any stress. The torque in the bonds just before they break does not nearly reach the maximum. I tried playing around with the relevant parameters but can't produce significantly better results.
What am I doing wrong?