LIGGGHTS® - User Forum

Hi everyone,
I am now working on the simulation of Janssen effect with Liggghts. The command I used in the input script is
"stress/atom" , no keywords is attached after this command. (The keywords attached can be ke,pair, bond,angle, dihedral, improper, kspace, fix, or virial ).
A packing is simulated in a cylinder with 20 0000 granules.

My liggghts always works, but today when I changed Young's modulus from 5e6 to 20e9（I am using Hertz model to simualte sand particles）. It stays at step one and there is no error message. I waited a long time, it;s still at step one. Can anybody guide me ?Appreciate it!!

Thanks
xiaobaishu

Hey guys,

I try to do the hopper tutorial. Therefore I take following code :

# Import mesh from cad:
fix cad1 all mesh/surface file meshes/hopper.stl type 2 scale 0.001
# Use the imported mesh as granular wall
fix geometry all wall/gran/hertz/history mesh n_meshes 1 meshes cad1
# Create stopper for funnel
fix stopper all wall/gran/hertz/history primitive type 2 zplane0.0
# Define the physics
pair_style gran/hertz/history
pair_coeff * *


Dear LIGGGHTSers,

What is the reference for the Hooke/hysteresis model implemented in the NORMAL_MODEL_HOOKE_HYSTERESIS.h? i cannot find it in the documentation. Is it the Linear Elastic-palstic Ahhesive model (Luding 2008)? Thank you.
Best regards,
Zyan,

Hi,

I am trying to use IF command and I getting this error "ERROR: Unknown command: { (../input.cpp:293) "
if "${typ1atoms} == 0.0" then { variable velcity1 equal 0.0 }

Can anyone please help me?

Thank you.

Is it possible to have access to the STL file used in LIGGGHTS_Tutorial.pdf, I mean STL files of Shear Cell or other examples?

Thanks

Hello everyone

I am pretty new to LIGGGHTS and DEM simulations. I am trying to model a wet granular system. I want to know if LIGGGHTS has the equation of interparticle force of the capillary bridge for simulating wet granular systems?

Regards

Halimeh

Hello,
When i use the command "fix...addtorque" to add torque to one particle, it happens an error " invalid fix style: "addtorque" " . Did anybody encountered this kind of situation?

thanks

Hello,
I want to limit particle rotation strictly,but i can no find relative command in liggghts.Have anybody used this command?

all thanks
K.cheng

Hi,

I am looking for a way to write particle-fluid interaction force of specific particle to a file. Normally I use Fix/print to output other information of atoms such as id,x,y,z or fx,fy,fz by pre-defining variables. However for dragforce, I am confused how to define variable for it.

For example one of my trials and it was failed below.

variable ID equal f_dragforce1[id_of_particle]

The structure of dragforce array might not be the same as those of normal force, fx,fy,fz in which we can point, e.g, fx[id_of_particle].