LIGGGHTS® - User Forum

Hello Christoph.
I was playing around with liggghts and I tried to first:
fix container all mesh/gran silo.stl 1 1.0 0 0 0 0 0 0
fix container_wall all wall/gran/hertz/history 1 0 mesh/gran 1 container

Then after some running steps I tried to:

unfix container_wall
run 1000
But I have a segmentation fault in the first iteration of the run 1000 command.
I've debugged a bit, and found that the fix is deleted, but when running the deleted fix is invoked again in Verlet::run()
if (n_pre_force) modify->pre_force(vflag);

Hi,
I want to pour two different diameters particles in simulation box, I used following script but couldn't put different diameters but just single, print-out is also given below:
....
.....

fix pts1 all particletemplate/sphere 786 atom_type 1 density constant 2460 radius constant 0.0020
fix pts2 all particletemplate/sphere 786 atom_type 1 density constant 2460 radius constant 0.003
fix pdd1 all particledistribution/discrete 6778 1 pts1 0.5 pts2 0.5
.....
......

region bc cylinder z 0 0 0.088 0.251 0.4 units box #bc block 0.0 0.239 0.0 0.239 1.2 1.5 units box

Hi !
Is this possible in liggghts to create the sound waves frequency and propagate it through granular media ?
Best
maz

Hi,
The new LIGGGHTS 1.2.3 beta doesn't write restart file, may be there is bug.
Thanks,
Ram

Hi,
I want to create 2D layer of beads. fix pour only works in 3D while lattice is not working with 2D. Any help will be appreciated.
Thanks,
Ram

i download the new version and followed the same steps to install it as i followed for the last versions. It was installed successfully and did not give any error in the end.The message in the end is as

"size ../lmp_fedora
text data bss dec hex filename
2677691 2572 10416 2690679 290e77 ../lmp_fedora
make[1]: Leaving directory `/home/sajjad/Desktop/liggghts_1p2p3-beta /src/Obj_fedora'
[sajjad@localhost src]$ "

But when i write the command " lmp_fedora" it gives

bash: lmp_fedora: command not found

Or when i execute any input file it gives

Hi,
I have imported rectangular mesh wall vertically in simulation box and now want to find total pressure experted by the particles. To do this, i have made mesh with no triangles, just one triangle of whole CAD. I don't want to measure pressure as function of height but total pressure at a time. Is this right way of doing?

Thanks,
Ram

Hello everyone,

I want to know if it is possible to use two different neighbor lists in my simulation. I use one neighbor list to load once my interactions via a txt file to define two bodies and now I want to detect the new interactions between these two bodies created during my simulation. To do this, I need to use a second neighbor list linked to a second pair_style.

Please, can you help me to do that ?

Hi, all

Could someone please tell me how to use the compute pair/gran/local and the dump local command to output pair forces in detail? I do not know how to use them. Actually, after dump the pair forces, it will be possible for me to extend the pizza.py to realize them in Paraview.

Could I add these two lines in the input file?
.....
compute 2 all pair/gran/local force
.....
dump dmpf all local 1000 dump.force c_2 #or c_2[1] c_2[2] c_2[3]
................

Hi, Christoph. I have a question about Rayleigh time:

Question 1:
in code:

rayleigh_time_i=M_PI*r[i]*sqrt(density[i]/shear_mod)/(0.1631*nu->values[type[i]-1]+0.8766)

in doc
dt_r =PI*r*sqrt(rho/Y)/(0.1631*n+0.8766),

but in doc Young Modulus instead of shear_mod, I want to known, which was right?

Question 2:

what are the Rayleigh time and Hertz time relationship with timestep of run, and how timestep should be determined.

Question 3:
Are there some references about this topic?

Thank you
xz