LIGGGHTS® - User Forum

Hi,
I'm having problems inserting particles.
I'm using pour/dev/packing command.
After few iterations they jump to +Z very quickly like rockets and all crash.
My file follows:

************************************************
atom_style granular
atom_modify map array
boundary m m m
newton off
communicate single vel yes
units si

region reg block -0.015 0.015 -0.015 0.015 -0.32 10 units box
create_box 1 reg
neighbor 0.0200 bin
neigh_modify delay 0

# Material properties required for new pair styles

Hey all,

I've modified the basic 'packing' example, to have 3 particle types with different properties (instead of 1 type) and i'm trying to generate a random packing of this system. (3 types of particles each having its own radius and density). I don't try to make them grow, so I removed the growing radius part commands.

Anyway, when I visualize the system with Paraview, I see that I only get one type of particles, all with the same size, instead of the specified distribution of particles as seen in my script.

Hi,
I have simulation box filled with particles, I want to move cluster of some particles in this box. To do so, i defined one spherical region and then apply following command:
....
....
region mySphere sphere .........
group myGroup region mySphere
fix 1 myRigid rigid group 1 myGroup
...
...

Then I want to move this as spherical body made of particle in the simulation box consists of other particles.
Is this right way of doing this? When i run the simulation then it prompts:

447 atoms in group myGroup
ERROR: One or zero atoms in rigid body

Hi,
I'm trying LIGGGHTS in parallel. For example:
mpirun -np 8 lmp_openmpi < in.case
When it starts it prints:
1 by 1 by 8 processor grid
The problems is that sometime it works well, sometime it crashes with this error:
ERROR on proc 0: Failed to allocate -1738615408 bytes for array neigh:binhead

For example it works well with:
communicate multi vel yes
units si
neighbor 0.001 bin
neigh_modify delay 0
variable radius1 equal 0.005 # m

It doesn't work with:
communicate multi vel yes

Hi,
I get error when I run simulation from restart file, the error message is :

......
ERROR: Could not locate a fix/property storing value(s) for coefficientRollingFriction

However, when I run simulation without MPI then it works fine (with restart).

Thanks,
Ram

Hello.
How to calculate the pressure and shear stress on a triangles of the mesh?
Is it the integral of the contact forces averaged by triangle's area?
Thanks.

Hi,
Is there a way to find total volume occupied by particles in simulation region during the run?
Thanks in advance,
Ram

Hi,

I'm doing some work relevant to the cohesion force. I'm confused with the cohesion model in LIGGGHTS. Could someone tell me what model and equations are used in the cohesion force in LIGGGHTS and what source files are implementing this model?

Thanks!

Jerry

Hello

I am having a problem installing LIGGGHTS... a very strange error...

I have used git to pull LIGGGHTS, but when compiling I get a whole list of errors going...
[root@Jay src]# make fedora
grep: cfd_regionmodel_*.h: No such file or directory
make[1]: Entering directory `/home/Jay/LIGGGHTS/myliggghts/src/Obj_fedora'
Makefile:93: region_cone.d: No such file or directory
Makefile:93: improper.d: No such file or directory
Makefile:93: ewald.d: No such file or directory
Makefile:93: fix_wall_gran_hooke.d: No such file or dir....
etc etc....

Hi
I have tried to run Chute_wear example but because of another problem (syntax error) I could not use the normal 3 line commands to change dump file to VTKs.so I did some changes inside the input file to outputs directly vtk files (instead of dump file) . after visualization with Paraview I see a Chute which in animation some moving triangles appear on the surface .so I doubt if it is the real simulation or I am missing something like some particles which I see just affect of them on the surface (without seeing themselves).