LIGGGHTS® - User Forum

Hi,

I am trying to extract the shear stress on every mesh element of a surface/mesh/stress using "dump mesh/vtk" as instructed in the manual. The problem here is that I can't understand the structure of the output file. Do you have any tip or do you know any better way in this regard.

Thank you.
Mohammad

To simulate a scoop I would need the scoop mesh to move over a fixed distance and to rotate for a fixed angle sequentially. I tried to use a timestep calculated like this

variable deltatime equal sqrt(${rho}/($E/(2*(1+$v))))*c_minradi*PI/(0.1631*$v+0.876605)/5

and the set velocity of the mesh used in the

fix movecad1 all move/mesh mesh cad1 linear 0.0 0.0 ${scm1d}

to get the required number of timesteps

Hi, I want to dump simulation images that does not show the whole simulation region rather a part of it.

Mine is a cylindrical region in which the segregation of particles by induced vibration is being studied. When I dump the images with the following syntax of command, it dumps the whole cylinder along with the simulation box. What I want is to clip the image at half of the x-axis something like this http://www.cfdem.com/system/files/sc_10per_overlap_coord.png

Source file "tangential_model_no_history.h" contains string with number 90:
if (vrel != 0.0) Ft = min(Ft_friction, Ft_damping) / vrel;
but this expression does not correlate with the main formula for force between particles (see doc/pair_gran.html), where the tangential part F_t consists of two components:
Ft_friction minus(!) Ft_damping

Simple example of collision of two rough particles without viscosity (gammat = 0 or Ft_damping = 0) shows that the value of tangential force Ft always will be equal zero, that is completely wrong.

Hello,

I want to restrict the overlap between particles to 1 % of particle diameter.
Is it possible to achieve this in LIGGGHTS without tweaking Kn values? May be I missed some feature/fix?

Thanks and kind regards,
Vinay

Hello, All!

I understand that we can output the STL files for the mesh surface.
Just wondering if LIGGGHTS is capable of reproducing the STL files for all the particle surfaces?
Many thanks!

Regards,
GH

I want to know if it is possible to excite the imported geometry in a random manner, as opposed to the command " WIGGLE" which excites my imported base in a simple sinusoidal manner only. I need to randomly vibrate my geometry. Is it possible in LIGGGHTS ? or where can I find this feature, please help.

regards,

Anand

Hi Everyone

While running my program, after some timesteps, the particles tend to move away from the outer areas as shown in figures. why is it that I am not getting a good composition?

Also the particles are not settling down properly. What should I do about that?

I am attaching my input file also

Regards
Hari

Hi everyone,

After running my program with insert/pack, in the visualisation majority of the particles tend to stick to quadrant region out of the total insertion region defined. I haven't been able to debug the mistake.

Can anyone help me?

I am attaching the input file and log file along with the pics of the result.

Regards
Hari

Dear community,

I am simulating powder particles with dipole moments in the gradient field. That are DIPOLE and MISC packages. In the 3.2 LIGGGHTS version they were cut out. Is it possible to somehow use them? Or the only way to use 3.1.0 version?

Faithfully yours,
Oksana.