LIGGGHTS® - User Forum

Hi, everyone, i'm new here. I used LIGGGHTS to simulate pouring problem. The balls are poured into a cylinder under gravity. After the calculation, i got the pressure on the bottom of wall. I would like to know this relationship between this pressure and the weight of balls. Based on soil mechanics, i know the pressure on the bottom wall should be equal the the weight of balls divided by the bottom area (Here i need to mention i am not familar with particle mechanics). Anyone can help me?

Hi
There is error when new beta version starts to write restart file in the end. I tired with both beta versions and also changed system. Error is:

Total # of neighbors = 216699
Ave neighs/atom = 5.28534
Neighbor list builds = 5595
Dangerous builds = 0
System init for write_restart ...
*** glibc detected *** lmp_fedora: free(): invalid pointer: 0xb0de6008 ***
*** glibc detected *** lmp_fedora: free(): invalid pointer: 0xb0e58008 ***
*** glibc detected *** lmp_fedora: double free or corruption (out): 0xb0dc8008 ***
======= Backtrace: =========
======= Backtrace: =========

Hi Christoph,
I am dumping force on base (mesh CAD) due to granular packing in cylinder, Base is moving downward. Practically the weight ( hence force along z-axis) felt by base should be constant during course of time but is it changing linearly. I am attaching the file herewith. Commands in the script are given as under:

...
fix cad2 all mesh/gran/stressanalysis base.stl 1 0.01 5. 5. 10 0. 0. 0.
...
fix movecad all move/mesh/gran linear 0. 0.0 -0.00082 cad2
....
dump dumpstl2 all mesh/gran/VTK 50 post/cad2/dump*.vtk stress cad2

Hi Christoph,
I have problem with new versions, i poured particles with version 1.1.9 and now I can run continue my simulation with new versions. Today i deleted the old version so I need LIGGGHTS 1.1.9. The following is error message when i run the restart file with 1.1.10 and 1.2 Beta:

......
WARNING: Restart file version does not match LAMMPS version
restart file = LIGGGHTS 1.1.9 based on lammps-10Mar10, LAMMPS = LIGGGHTS 1.1.10 based on lammps-10Mar10
orthogonal box = (-0.01 -0.01 -0.01) to (0.41 0.41 1.31)
1 by 1 by 4 processor grid
425350 atoms

Hi, all

How can I make that there's no friction between walls and particles while there's friction among particles?

Could someone tell me this in detail?

Thanks in advance.

Thanks!

Hi all,

I need to change a parameter for my walls. E.g. I want to change the damping flag (or the velocity amplitude if I am doing wiggle with a LAMMPS-style plane wall).

My impression is that I need to use the command fix_modify in my input script. But then I need to add the function modify_param in my wall class, which will take as inputs the arguments of fix_modify and reset the values I require.

Does this sound fine, or am I missing an easier way of doing this?

Thanks,

George

Hi all,
How can I use LJ units for density and yougsModulus?
Thanks in advance,
Ram

Hi Christoph,

I would want to write a new dump class (dump_gran) which saves the connectivity and the scalars as: normal force, damage parameter, radius. Thus, it will be possible to display with paraview the lattice beams or the chain force for granular simulations. But I need help to understand the class Dump_mesh and know where the functions are called:

Hey Everyone,

I'm trying to build LIGGGHTS in Cygwin (and before anyone suggests otherwise - Yes, I need to do it in Cygwin, and other platforms won't work for what I require). I've edited the makefile.cygwin and the .bashrc files and have overcome most of the problems associated with building the executable. However, after "make cygwin" runs for a while, I get the following errors and the build does not complete:

#C:\MSDEV\LIB -o ../lmp_cygwin
#c++: C:MSDEVLIB: No such file or directory
#make[1]: *** [../lmp_cygwin] Error 1

Hi,

I want move the side walls as a function of time t to conduct the undrained triaxial test with no volumetric change. However, when I try this fix move variable command, it seems to be some errors in my script:

variable dy equal 0.01/(0.1+${vc}*dt*(step-40000))-0.1
variable vy equal 0.01*${vc}/(0.1-${vc}*dt*(step-40000))^2
fix F_moveleft all move/mesh/gran variable NULL -0.05-0.5*${dy} NULL NULL -0.5*${vy} NULL units box leftwall 1

The output of liggghts:

variable vc equal -0.1
variable dy equal 0.01/(0.1+${vc}*dt*(step-40000))-0.1