LIGGGHTS® - User Forum

Hello everyone,
I am learning how to do simulations by Liggghts. Now, I want two kinds of powders to fall onto the bottom of the domain. But it showed that my particles directly went across the domain and disappeared. I tried to decrease my time step to 1/10, but the problem was still unfixed. Could anyone please help me to deal with this problem? The input script is below. Thanks very much for your help.

atom_style sphere
boundary f f f
newton off
atom_modify map array

communicate single vel yes
units si

processors 2 1 2

Hello,

I have a single particle resting on a plane which I then set spinning. The particle experiences a constant angular velocity, despite an opposing torque (attached plot). I create the particle on top of a primitive wall and allow it to settle before setting omega_z to 1 m/s. With rolling friction (EPSD) on, there is a small but constantly decreasing z torque, however the particle's omega_z remains at 1m/s. What to do I need to fix about my script (attached) in order for the particle to see a decrease in angular velocity over time? Thanks!

Eric

I am working on a standard hopper discharge simulation to create a basis for some future work in my program. In trying to learn LIGGGHTS by itself, I am able to create particles and load the "STL" file for the hopper mesh, However, when I run the particles, there is no contact detection it seems between the particle and the mesh wall supplied.

Do you have LIGGGHTS code, geometry and meshes for triaxial tests? If you have, could you please share with me? I am learning the LIGGGHTS to simulate the triaxial test. It would be a great help if you could share it with me.

My email is ripon120535@gmail.com

Thank you very much.

Hi, I am trying to add the Thornton and Ning contact model to LIGGGHTS-WITH-BONDS developed by richti. There are just way too many errors when compiling and I am unable to figure out an elegant way to add the Thornton and Ning model (from normal_model_thornton_ning.h in LIGGGHTS-PUBLIC-master) to LIGGGHTS-WITH-BONDS. Can someone please help?

Hello everyone,

i wanted to write the temperatures of the particles in a certain region into a text or csv file. Getting the mass, the number or other many properties of the particles in a certain region is possible easily with region functions, however i could not find any region function with temperature. For example for mass i wrote this and it works.

variable m1 equal mass(all,outlet)
variable t equal step*dt
fix data all print 100000 "$t,${m1}" file ../DEM/Messdaten/mass.csv title "Zeit(s),Masse_in(kg)"

Can I get little bit help?

I am doing simulation in rotating drum.
When I put my timestep to 0.0001 it is running without any problem. But I need more information about particles so I tried to make timesteps smaller which means 0.00001.
After decreasing the timestep , drum starts rotating while particles are inserting. And another problem is drum stops after certain timestep and particles move without drum's movement. Which is weird.

hallo everyone,

I would like to pack a mixture of two kinds of powders, 5000 for atom type 1 and 2000 for atom type 2. But the text file showed that there were only 5000 in total. Can anyone tell me how I can deal with it?

Best regards,
Sang

Hi,

Hello, I am using LIGGGHTS-WITH-BONDS and I would like to set my bond cutoff length as
cutoff = (R1 + R2) + G*(R1 + R2)
where R1 and R2 are the radii of the two particles and G is a value defined by me. How can I implement this into the line
fix bondcr all bond/create/gran 1 1 1 cutoff 1 26